SR
Sam Reaves
Tue, May 15, 2012 1:13 AM
For conformal coating I recommend Humiseal Acrylic 1B73 in aerosol. You can
also get it in brush form. I believe that Chemtronics used to offer acrylic
coating as well, maybe even re-packaging the Humiseal product. I don't know
if there is a source for small quantities of Humiseal but it is a fine
product.
I have also used Krylon clear acrylic that you can get at Wall-Mart in a
pinch. The acrylic coatings I have found are better for HiZ circuits that
have requirements for low-leakage. Consult the can for solvents and make
sure that what you are coating are compatible with Toluene, Ketones,
Acetone, etc. be careful around connectors as the coating will wick into
connectors as the 1B73 is a fairly low viscosity. You can also get Humiseal
formulations 1B38 and 1B66 which are also Acrylics but are brush on and
require a one gallon minimum purchase. The shipping cost for a gallon is
almost as much as the product due to the requirement that it be shipped as
a hazardous material (flameable). The acrylics can be dissolved with MEK or
any of the solvents I have listed above. You can remove a small amount with
a Q-Tip.
The Humiseal product also has a UV indicator in it that glows blue under a
black light so you can check coverage.
I have tested Humiseal Acrylic on probably 1000+ PCB's and it has yet to
fail me. It is also easy to rework and re-coat after repairs.
You can also get polyurethane coatings but I do not recommend them since
they are more difficult you use, not as easy to remove
and have better performance for HiZ and RF circuits.
Good luck and let us know how you make out.
Sam
W3OHM
http://www.hmcelectronics.com/product/Chemtronics/CTAR12
On Mon, May 14, 2012 at 7:31 PM, time-nuts-request@febo.com wrote:
Send time-nuts mailing list submissions to
time-nuts@febo.com
To subscribe or unsubscribe via the World Wide Web, visit
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When replying, please edit your Subject line so it is more specific
than "Re: Contents of time-nuts digest..."
Today's Topics:
- Re: Why are 1PPS signals so skinny? (Jim Hickstein)
- Re: Why are 1PPS signals so skinny? (Azelio Boriani)
- Re: wwvb weak on east coast especially when the pre-amps
under wa... (Michael Blazer)
- Re: wwvb weak on east coast especially when the pre-amps
under wa... (Azelio Boriani)
- Re: Why are 1PPS signals so skinny? (Michael Blazer)
- Re: Why are 1PPS signals so skinny? (Bob Camp)
- Re: wwvb weak on east coast especially when thepre-amps under
wa... (Alan Melia)
Message: 1
Date: Mon, 14 May 2012 18:18:20 -0500
From: Jim Hickstein jxh@jxh.com
To: time-nuts@febo.com
Subject: Re: [time-nuts] Why are 1PPS signals so skinny?
Message-ID: 4FB192BC.4060801@jxh.com
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 2012/05/14 18:02, time-nuts-request@febo.com wrote:
military standards.
Hmm. Doesn't find MIL-TGDBP-41. I got this from my (now late) great
uncle, Bob
Sedgwick -- who was to hydraulics what I am to computers, only he has a
number
of patents.
Some smart-aleck at Wright Field, as it then was, put this on a drawing,
and it
went without comment for quite a while until someone tried to look it up.
This
escalated to a bird colonel, who then tracked down the miscreant.
It stands for Make It Like The G-D Blueprint For Once.
Message: 2
Date: Tue, 15 May 2012 01:21:26 +0200
From: Azelio Boriani azelio.boriani@screen.it
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Why are 1PPS signals so skinny?
Message-ID:
<CAL8XPmOc8cLJ3aGBcqJsJB=FbW5XTQ-_FY54R9edDUDUX+ADTg@mail.gmail.com
Content-Type: text/plain; charset=ISO-8859-1
Maybe the correct number is MIL-STD-188-115?
On Tue, May 15, 2012 at 1:18 AM, Jim Hickstein jxh@jxh.com wrote:
Hmm. Doesn't find MIL-TGDBP-41. I got this from my (now late) great
uncle, Bob Sedgwick -- who was to hydraulics what I am to computers, only
he has a number of patents.
Some smart-aleck at Wright Field, as it then was, put this on a drawing,
and it went without comment for quite a while until someone tried to look
it up. This escalated to a bird colonel, who then tracked down the
miscreant.
It stands for Make It Like The G-D Blueprint For Once.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
The other option of course is to pressurise the box with dry air to
a positive pressure differential, such that the net flow is always
at all points, but it's probably easier just to provide a drain hole:-)
However, whilst a drain hole will prevent the build up of a lake inside
enclosure it still doesn't prevent condensation forming on circuit
and powered circuit boards and condensation don't really go well
As per earlier comments, it's quite difficult to keep any externally
mounted enclosure totally moisture free, so it's much easier to accept
inevitable and allow for it.
In a past life I designed quite a few circuit boards that were required
be fitted in externally mounted vented enclosures, so not a great deal
pressurisation there then:-), and I usually specified that both sides
should be sprayed with a plastic coating following final test.
I can't remember now exactly what this stuff was called, but it was
readily available in the UK from both RS and Farnell as an aerosol
that provided a good barrier but was a bit more flexible than the usual
spec conformal coatings.
It melted easily under a soldering iron, albeit with a foul pong:-), so
reworking was no problem, and resisted moisture remarkably well.....
problem solved:-)
Nigel
GM8PZR
In a message dated 14/05/2012 23:10:30 GMT Daylight Time,
arnold.tibus@gmx.de writes:
The only solutions I think:
Apply air pressure tight boxes having a breathing hole an the bottom,
mount the
box that no rain and water can penetrate from the top or sides. If the
hole is big enough,
eg. 2mm, no pressure difference is possible and no pumping effect will
occur.
(If the hole is too wide, small animals may penetrate).
Or,
when using a pressure tight box, it must be stiff and sealed to
withstand under all
temperature conditions more then 1 bar/ 100 kPa. Do not forget that all
feed
throughs must be of real hermetic type, normal coaxial connectors are
not tight!
Don't route cables directly in, because no cable braid or mesh is vapor
tight.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
and follow the instructions there.
Content-Type: text/plain; charset=ISO-8859-1
We use the Plastik70 from Kontakt chemie
On Tue, May 15, 2012 at 1:23 AM, Michael Blazer mblazer@satx.rr.com
wrote:
The other option of course is to pressurise the box with dry air to
a positive pressure differential, such that the net flow is always
outwards
at all points, but it's probably easier just to provide a drain hole:-)
However, whilst a drain hole will prevent the build up of a lake inside
the
enclosure it still doesn't prevent condensation forming on circuit
boards,
and powered circuit boards and condensation don't really go well
together.
As per earlier comments, it's quite difficult to keep any externally
mounted enclosure totally moisture free, so it's much easier to accept
inevitable and allow for it.
In a past life I designed quite a few circuit boards that were required
to
be fitted in externally mounted vented enclosures, so not a great deal
pressurisation there then:-), and I usually specified that both sides
should be sprayed with a plastic coating following final test.
I can't remember now exactly what this stuff was called, but it was
readily available in the UK from both RS and Farnell as an aerosol
plastic spray
that provided a good barrier but was a bit more flexible than the usual
MOD
spec conformal coatings.
It melted easily under a soldering iron, albeit with a foul pong:-), so
reworking was no problem, and resisted moisture remarkably well.....
problem solved:-)
Nigel
GM8PZR
In a message dated 14/05/2012 23:10:30 GMT Daylight Time,
arnold.tibus@gmx.de writes:
The only solutions I think:
Apply air pressure tight boxes having a breathing hole an the bottom,
mount the
box that no rain and water can penetrate from the top or sides. If the
hole is big enough,
eg. 2mm, no pressure difference is possible and no pumping effect will
occur.
(If the hole is too wide, small animals may penetrate).
Or,
when using a pressure tight box, it must be stiff and sealed to
withstand under all
temperature conditions more then 1 bar/ 100 kPa. Do not forget that
feed
throughs must be of real hermetic type, normal coaxial connectors are
not tight!
Don't route cables directly in, because no cable braid or mesh is
Message: 5
Date: Mon, 14 May 2012 18:26:58 -0500
From: Michael Blazer mblazer@satx.rr.com
To: time-nuts@febo.com
Subject: Re: [time-nuts] Why are 1PPS signals so skinny?
Message-ID: 4FB194C2.6090401@satx.rr.com
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
I haven't heard that one before. I try to slip in the TLAR check in all
the test procedures I write. When 'they' ask, I look at it and say:
"That Looks About Right".
Mike
On 5/14/2012 6:18 PM, Jim Hickstein wrote:
Hmm. Doesn't find MIL-TGDBP-41. I got this from my (now late) great
uncle, Bob Sedgwick -- who was to hydraulics what I am to computers,
only he has a number of patents.
Some smart-aleck at Wright Field, as it then was, put this on a
drawing, and it went without comment for quite a while until someone
tried to look it up. This escalated to a bird colonel, who then
tracked down the miscreant.
It stands for Make It Like The G-D Blueprint For Once.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Message: 6
Date: Mon, 14 May 2012 19:30:49 -0400
From: Bob Camp lists@rtty.us
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Why are 1PPS signals so skinny?
Message-ID: 0CE3BEF7-A1BA-4CE1-8A74-3364B2A80302@rtty.us
Content-Type: text/plain; charset=iso-8859-1
Hi
I would bet that the basic electrical definition of the "skinny" PPS dates
at least to the mid 50's if not earlier.
Bob
On May 14, 2012, at 3:20 PM, Magnus Danielson wrote:
Mark& Azelio,
Or even 10V into 50ohm, 20us... See figure 3-4 in ICD-GPS-060.
http://www.navcen.uscg.gov/pdf/gps/ICD-GPS-060B.pdf
More modern 3-5.5V into 50ohm, 20us.
Above are two standards demanding short skinny 1PPS pulses. Are there
other standards with distinct shape requirements on 1PPS pulses?
You need to look at MIL STD 188/155 which if I recall things was
initially formed in the 60thies.
An AccuBeat presentation actually says that the PPS was originally
The MIL STD 188/155 is actually a 10 V peak level, so it was much hotter
than we are used to know. It specified 5 MHz as base frequency, or power of
2 multiples (10, 20, 40 MHz... ).
It was later reformulated in the PTTI spec, which ICD GPS 060 is a
derivate. The 50 ns rise and 1 us fall slopes comes from that spec.
I was not able to find MIL STD 188-155 on the net right now, but I have
been able to download it before, so if someone is a more lucky it should
surface. I should have my download somewhere.
and follow the instructions there.
Message: 7
Date: Tue, 15 May 2012 00:32:11 +0100
From: "Alan Melia" alan.melia@btinternet.com
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Subject: Re: [time-nuts] wwvb weak on east coast especially when
thepre-amps under wa...
Message-ID: 012501cd3229$cb66eae0$4001a8c0@lark
Content-Type: text/plain; charset="iso-8859-1"
Well almost Nigel, if you look at molecule mean velocities they are always
able to diffuse down a concentration gradient (i.e from wet into dry)
despite a small reverse presure gradient. It just takes longer under those
conditions :-))....which is often "enough"
Alan G3NYK
----- Original Message -----
From: GandalfG8@aol.com
To: time-nuts@febo.com
Sent: Tuesday, May 15, 2012 12:01 AM
Subject: Re: [time-nuts] wwvb weak on east coast especially when
thepre-amps
under wa...
The other option of course is to pressurise the box with dry air to
a positive pressure differential, such that the net flow is always
at all points, but it's probably easier just to provide a drain hole:-)
However, whilst a drain hole will prevent the build up of a lake inside
enclosure it still doesn't prevent condensation forming on circuit
and powered circuit boards and condensation don't really go well
As per earlier comments, it's quite difficult to keep any externally
mounted enclosure totally moisture free, so it's much easier to accept
inevitable and allow for it.
In a past life I designed quite a few circuit boards that were required
be fitted in externally mounted vented enclosures, so not a great deal
pressurisation there then:-), and I usually specified that both sides
should be sprayed with a plastic coating following final test.
I can't remember now exactly what this stuff was called, but it was
readily available in the UK from both RS and Farnell as an aerosol
that provided a good barrier but was a bit more flexible than the usual
spec conformal coatings.
It melted easily under a soldering iron, albeit with a foul pong:-), so
reworking was no problem, and resisted moisture remarkably well.....
problem solved:-)
Nigel
GM8PZR
In a message dated 14/05/2012 23:10:30 GMT Daylight Time,
arnold.tibus@gmx.de writes:
The only solutions I think:
Apply air pressure tight boxes having a breathing hole an the bottom,
mount the
box that no rain and water can penetrate from the top or sides. If the
hole is big enough,
eg. 2mm, no pressure difference is possible and no pumping effect will
occur.
(If the hole is too wide, small animals may penetrate).
Or,
when using a pressure tight box, it must be stiff and sealed to
withstand under all
temperature conditions more then 1 bar/ 100 kPa. Do not forget that all
feed
throughs must be of real hermetic type, normal coaxial connectors are
not tight!
Don't route cables directly in, because no cable braid or mesh is vapor
tight.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
and follow the instructions there.
For conformal coating I recommend Humiseal Acrylic 1B73 in aerosol. You can
also get it in brush form. I believe that Chemtronics used to offer acrylic
coating as well, maybe even re-packaging the Humiseal product. I don't know
if there is a source for small quantities of Humiseal but it is a fine
product.
I have also used Krylon clear acrylic that you can get at Wall-Mart in a
pinch. The acrylic coatings I have found are better for HiZ circuits that
have requirements for low-leakage. Consult the can for solvents and make
sure that what you are coating are compatible with Toluene, Ketones,
Acetone, etc. be careful around connectors as the coating will wick into
connectors as the 1B73 is a fairly low viscosity. You can also get Humiseal
formulations 1B38 and 1B66 which are also Acrylics but are brush on and
require a one gallon minimum purchase. The shipping cost for a gallon is
almost as much as the product due to the requirement that it be shipped as
a hazardous material (flameable). The acrylics can be dissolved with MEK or
any of the solvents I have listed above. You can remove a small amount with
a Q-Tip.
The Humiseal product also has a UV indicator in it that glows blue under a
black light so you can check coverage.
I have tested Humiseal Acrylic on probably 1000+ PCB's and it has yet to
fail me. It is also easy to rework and re-coat after repairs.
You can also get polyurethane coatings but I do not recommend them since
they are more difficult you use, not as easy to remove
and have better performance for HiZ and RF circuits.
Good luck and let us know how you make out.
Sam
W3OHM
http://www.hmcelectronics.com/product/Chemtronics/CTAR12
On Mon, May 14, 2012 at 7:31 PM, <time-nuts-request@febo.com> wrote:
> Send time-nuts mailing list submissions to
> time-nuts@febo.com
>
> To subscribe or unsubscribe via the World Wide Web, visit
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> or, via email, send a message with subject or body 'help' to
> time-nuts-request@febo.com
>
> You can reach the person managing the list at
> time-nuts-owner@febo.com
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of time-nuts digest..."
>
>
> Today's Topics:
>
> 1. Re: Why are 1PPS signals so skinny? (Jim Hickstein)
> 2. Re: Why are 1PPS signals so skinny? (Azelio Boriani)
> 3. Re: wwvb weak on east coast especially when the pre-amps
> under wa... (Michael Blazer)
> 4. Re: wwvb weak on east coast especially when the pre-amps
> under wa... (Azelio Boriani)
> 5. Re: Why are 1PPS signals so skinny? (Michael Blazer)
> 6. Re: Why are 1PPS signals so skinny? (Bob Camp)
> 7. Re: wwvb weak on east coast especially when thepre-amps under
> wa... (Alan Melia)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 14 May 2012 18:18:20 -0500
> From: Jim Hickstein <jxh@jxh.com>
> To: time-nuts@febo.com
> Subject: Re: [time-nuts] Why are 1PPS signals so skinny?
> Message-ID: <4FB192BC.4060801@jxh.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> On 2012/05/14 18:02, time-nuts-request@febo.com wrote:
> > https://assist.daps.dla.mil/quicksearch/ is the search site for
> military standards.
>
> Hmm. Doesn't find MIL-TGDBP-41. I got this from my (now late) great
> uncle, Bob
> Sedgwick -- who was to hydraulics what I am to computers, only he has a
> number
> of patents.
>
> Some smart-aleck at Wright Field, as it then was, put this on a drawing,
> and it
> went without comment for quite a while until someone tried to look it up.
> This
> escalated to a bird colonel, who then tracked down the miscreant.
>
> It stands for Make It Like The G-D Blueprint For Once.
>
>
>
> ------------------------------
>
> Message: 2
> Date: Tue, 15 May 2012 01:21:26 +0200
> From: Azelio Boriani <azelio.boriani@screen.it>
> To: Discussion of precise time and frequency measurement
> <time-nuts@febo.com>
> Subject: Re: [time-nuts] Why are 1PPS signals so skinny?
> Message-ID:
> <CAL8XPmOc8cLJ3aGBcqJsJB=FbW5XTQ-_FY54R9edDUDUX+ADTg@mail.gmail.com
> >
> Content-Type: text/plain; charset=ISO-8859-1
>
> Maybe the correct number is MIL-STD-188-115?
>
> On Tue, May 15, 2012 at 1:18 AM, Jim Hickstein <jxh@jxh.com> wrote:
>
> > On 2012/05/14 18:02, time-nuts-request@febo.com wrote:
> >
> >> https://assist.daps.dla.mil/quicksearch/ is the search site for
> >> military standards.
> >>
> >
> > Hmm. Doesn't find MIL-TGDBP-41. I got this from my (now late) great
> > uncle, Bob Sedgwick -- who was to hydraulics what I am to computers, only
> > he has a number of patents.
> >
> > Some smart-aleck at Wright Field, as it then was, put this on a drawing,
> > and it went without comment for quite a while until someone tried to look
> > it up. This escalated to a bird colonel, who then tracked down the
> > miscreant.
> >
> > It stands for Make It Like The G-D Blueprint For Once.
> >
> >
> > _______________________________________________
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to
> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
> >
>
>
> ------------------------------
>
> Message: 3
> Date: Mon, 14 May 2012 18:23:31 -0500
> From: Michael Blazer <mblazer@satx.rr.com>
> To: time-nuts@febo.com
> Subject: Re: [time-nuts] wwvb weak on east coast especially when the
> pre-amps under wa...
> Message-ID: <4FB193F3.6000503@satx.rr.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Here's comparison for various type of conformal coating:
> http://mgchemicals.com/downloads/appguide/appguide0404.pdf.<
> https://assist.daps.dla.mil/quicksearch/>
>
> I think there is a type that is 'serviceable' and removable with alcohol.
>
> Mike
>
> On 5/14/2012 6:01 PM, GandalfG8@aol.com wrote:
> > The other option of course is to pressurise the box with dry air to
> ensure
> > a positive pressure differential, such that the net flow is always
> outwards
> > at all points, but it's probably easier just to provide a drain hole:-)
> >
> > However, whilst a drain hole will prevent the build up of a lake inside
> the
> > enclosure it still doesn't prevent condensation forming on circuit
> boards,
> > and powered circuit boards and condensation don't really go well
> together.
> >
> > As per earlier comments, it's quite difficult to keep any externally
> > mounted enclosure totally moisture free, so it's much easier to accept
> the
> > inevitable and allow for it.
> >
> > In a past life I designed quite a few circuit boards that were required
> to
> > be fitted in externally mounted vented enclosures, so not a great deal
> of
> > pressurisation there then:-), and I usually specified that both sides
> > should be sprayed with a plastic coating following final test.
> >
> > I can't remember now exactly what this stuff was called, but it was
> > readily available in the UK from both RS and Farnell as an aerosol
> plastic spray
> > that provided a good barrier but was a bit more flexible than the usual
> MOD
> > spec conformal coatings.
> > It melted easily under a soldering iron, albeit with a foul pong:-), so
> > reworking was no problem, and resisted moisture remarkably well.....
> >
> > problem solved:-)
> >
> > Nigel
> > GM8PZR
> >
> >
> >
> >
> >
> > In a message dated 14/05/2012 23:10:30 GMT Daylight Time,
> > arnold.tibus@gmx.de writes:
> >
> > The only solutions I think:
> > Apply air pressure tight boxes having a breathing hole an the bottom,
> > mount the
> > box that no rain and water can penetrate from the top or sides. If the
> > hole is big enough,
> > eg. 2mm, no pressure difference is possible and no pumping effect will
> > occur.
> > (If the hole is too wide, small animals may penetrate).
> > Or,
> > when using a pressure tight box, it must be stiff and sealed to
> > withstand under all
> > temperature conditions more then 1 bar/ 100 kPa. Do not forget that all
> > feed
> > throughs must be of real hermetic type, normal coaxial connectors are
> > not tight!
> > Don't route cables directly in, because no cable braid or mesh is vapor
> > tight.
> > _______________________________________________
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
> >
> >
>
>
> ------------------------------
>
> Message: 4
> Date: Tue, 15 May 2012 01:25:54 +0200
> From: Azelio Boriani <azelio.boriani@screen.it>
> To: Discussion of precise time and frequency measurement
> <time-nuts@febo.com>
> Subject: Re: [time-nuts] wwvb weak on east coast especially when the
> pre-amps under wa...
> Message-ID:
> <CAL8XPmPCB-DWCpoT0NmfP+TdpdRcK-XjXxVJWyTJA+RQmux9dg@mail.gmail.com
> >
> Content-Type: text/plain; charset=ISO-8859-1
>
> We use the Plastik70 from Kontakt chemie
>
> On Tue, May 15, 2012 at 1:23 AM, Michael Blazer <mblazer@satx.rr.com>
> wrote:
>
> > Here's comparison for various type of conformal coating:
> > http://mgchemicals.com/downloads/appguide/appguide0404.pdf.<
> > https://assist.daps.dla.mil/quicksearch/>
> >
> > I think there is a type that is 'serviceable' and removable with alcohol.
> >
> > Mike
> >
> >
> > On 5/14/2012 6:01 PM, GandalfG8@aol.com wrote:
> >
> >> The other option of course is to pressurise the box with dry air to
> ensure
> >> a positive pressure differential, such that the net flow is always
> >> outwards
> >> at all points, but it's probably easier just to provide a drain hole:-)
> >>
> >> However, whilst a drain hole will prevent the build up of a lake inside
> >> the
> >> enclosure it still doesn't prevent condensation forming on circuit
> >> boards,
> >> and powered circuit boards and condensation don't really go well
> >> together.
> >>
> >> As per earlier comments, it's quite difficult to keep any externally
> >> mounted enclosure totally moisture free, so it's much easier to accept
> the
> >> inevitable and allow for it.
> >>
> >> In a past life I designed quite a few circuit boards that were required
> >> to
> >> be fitted in externally mounted vented enclosures, so not a great deal
> of
> >> pressurisation there then:-), and I usually specified that both sides
> >> should be sprayed with a plastic coating following final test.
> >>
> >> I can't remember now exactly what this stuff was called, but it was
> >> readily available in the UK from both RS and Farnell as an aerosol
> >> plastic spray
> >> that provided a good barrier but was a bit more flexible than the usual
> >> MOD
> >> spec conformal coatings.
> >> It melted easily under a soldering iron, albeit with a foul pong:-), so
> >> reworking was no problem, and resisted moisture remarkably well.....
> >>
> >> problem solved:-)
> >>
> >> Nigel
> >> GM8PZR
> >>
> >>
> >>
> >>
> >>
> >> In a message dated 14/05/2012 23:10:30 GMT Daylight Time,
> >> arnold.tibus@gmx.de writes:
> >>
> >> The only solutions I think:
> >> Apply air pressure tight boxes having a breathing hole an the bottom,
> >> mount the
> >> box that no rain and water can penetrate from the top or sides. If the
> >> hole is big enough,
> >> eg. 2mm, no pressure difference is possible and no pumping effect will
> >> occur.
> >> (If the hole is too wide, small animals may penetrate).
> >> Or,
> >> when using a pressure tight box, it must be stiff and sealed to
> >> withstand under all
> >> temperature conditions more then 1 bar/ 100 kPa. Do not forget that
> all
> >> feed
> >> throughs must be of real hermetic type, normal coaxial connectors are
> >> not tight!
> >> Don't route cables directly in, because no cable braid or mesh is
> vapor
> >> tight.
> >> _______________________________________________
> >> time-nuts mailing list -- time-nuts@febo.com
> >> To unsubscribe, go to
> >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> >> and follow the instructions there.
> >>
> >>
> >> _______________________________________________
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to
> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
> >
>
>
> ------------------------------
>
> Message: 5
> Date: Mon, 14 May 2012 18:26:58 -0500
> From: Michael Blazer <mblazer@satx.rr.com>
> To: time-nuts@febo.com
> Subject: Re: [time-nuts] Why are 1PPS signals so skinny?
> Message-ID: <4FB194C2.6090401@satx.rr.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> I haven't heard that one before. I try to slip in the TLAR check in all
> the test procedures I write. When 'they' ask, I look at it and say:
> "That Looks About Right".
> Mike
>
> On 5/14/2012 6:18 PM, Jim Hickstein wrote:
> > On 2012/05/14 18:02, time-nuts-request@febo.com wrote:
> >> https://assist.daps.dla.mil/quicksearch/ is the search site for
> >> military standards.
> >
> > Hmm. Doesn't find MIL-TGDBP-41. I got this from my (now late) great
> > uncle, Bob Sedgwick -- who was to hydraulics what I am to computers,
> > only he has a number of patents.
> >
> > Some smart-aleck at Wright Field, as it then was, put this on a
> > drawing, and it went without comment for quite a while until someone
> > tried to look it up. This escalated to a bird colonel, who then
> > tracked down the miscreant.
> >
> > It stands for Make It Like The G-D Blueprint For Once.
> >
> > _______________________________________________
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to
> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
> >
> >
>
>
>
> ------------------------------
>
> Message: 6
> Date: Mon, 14 May 2012 19:30:49 -0400
> From: Bob Camp <lists@rtty.us>
> To: Discussion of precise time and frequency measurement
> <time-nuts@febo.com>
> Subject: Re: [time-nuts] Why are 1PPS signals so skinny?
> Message-ID: <0CE3BEF7-A1BA-4CE1-8A74-3364B2A80302@rtty.us>
> Content-Type: text/plain; charset=iso-8859-1
>
> Hi
>
> I would bet that the basic electrical definition of the "skinny" PPS dates
> at least to the mid 50's if not earlier.
>
> Bob
>
> On May 14, 2012, at 3:20 PM, Magnus Danielson wrote:
>
> > Mark, Azelio and Bj?rn,
> >
> > On 05/14/2012 06:33 PM, bg@lysator.liu.se wrote:
> >> Mark& Azelio,
> >>
> >> Or even 10V into 50ohm, 20us... See figure 3-4 in ICD-GPS-060.
> >>
> >> http://www.navcen.uscg.gov/pdf/gps/ICD-GPS-060B.pdf
> >>
> >> More modern 3-5.5V into 50ohm, 20us.
> >>
> http://contracting.tacom.army.mil/majorsys/jab/DAGR%20Interface%20Specification.pdf
> >>
> >> Above are two standards demanding short skinny 1PPS pulses. Are there
> any
> >> other standards with distinct shape requirements on 1PPS pulses?
> >
> > You need to look at MIL STD 188/155 which if I recall things was
> initially formed in the 60thies.
> >
> > An AccuBeat presentation actually says that the PPS was originally
> defined in it.
> >
> > The MIL STD 188/155 is actually a 10 V peak level, so it was much hotter
> than we are used to know. It specified 5 MHz as base frequency, or power of
> 2 multiples (10, 20, 40 MHz... ).
> >
> > It was later reformulated in the PTTI spec, which ICD GPS 060 is a
> derivate. The 50 ns rise and 1 us fall slopes comes from that spec.
> >
> > I was not able to find MIL STD 188-155 on the net right now, but I have
> been able to download it before, so if someone is a more lucky it should
> surface. I should have my download somewhere.
> >
> > Cheers,
> > Magnus
> >
> > _______________________________________________
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
>
>
>
>
> ------------------------------
>
> Message: 7
> Date: Tue, 15 May 2012 00:32:11 +0100
> From: "Alan Melia" <alan.melia@btinternet.com>
> To: "Discussion of precise time and frequency measurement"
> <time-nuts@febo.com>
> Subject: Re: [time-nuts] wwvb weak on east coast especially when
> thepre-amps under wa...
> Message-ID: <012501cd3229$cb66eae0$4001a8c0@lark>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Well almost Nigel, if you look at molecule mean velocities they are always
> able to diffuse down a concentration gradient (i.e from wet into dry)
> despite a small reverse presure gradient. It just takes longer under those
> conditions :-))....which is often "enough"
>
> Alan G3NYK
> ----- Original Message -----
> From: <GandalfG8@aol.com>
> To: <time-nuts@febo.com>
> Sent: Tuesday, May 15, 2012 12:01 AM
> Subject: Re: [time-nuts] wwvb weak on east coast especially when
> thepre-amps
> under wa...
>
>
> > The other option of course is to pressurise the box with dry air to
> ensure
> > a positive pressure differential, such that the net flow is always
> outwards
> > at all points, but it's probably easier just to provide a drain hole:-)
> >
> > However, whilst a drain hole will prevent the build up of a lake inside
> the
> > enclosure it still doesn't prevent condensation forming on circuit
> boards,
> > and powered circuit boards and condensation don't really go well
> together.
> >
> > As per earlier comments, it's quite difficult to keep any externally
> > mounted enclosure totally moisture free, so it's much easier to accept
> the
> > inevitable and allow for it.
> >
> > In a past life I designed quite a few circuit boards that were required
> to
> > be fitted in externally mounted vented enclosures, so not a great deal
> of
> > pressurisation there then:-), and I usually specified that both sides
> > should be sprayed with a plastic coating following final test.
> >
> > I can't remember now exactly what this stuff was called, but it was
> > readily available in the UK from both RS and Farnell as an aerosol
> plastic
> spray
> > that provided a good barrier but was a bit more flexible than the usual
> MOD
> > spec conformal coatings.
> > It melted easily under a soldering iron, albeit with a foul pong:-), so
> > reworking was no problem, and resisted moisture remarkably well.....
> >
> > problem solved:-)
> >
> > Nigel
> > GM8PZR
> >
> >
> >
> >
> >
> > In a message dated 14/05/2012 23:10:30 GMT Daylight Time,
> > arnold.tibus@gmx.de writes:
> >
> > The only solutions I think:
> > Apply air pressure tight boxes having a breathing hole an the bottom,
> > mount the
> > box that no rain and water can penetrate from the top or sides. If the
> > hole is big enough,
> > eg. 2mm, no pressure difference is possible and no pumping effect will
> > occur.
> > (If the hole is too wide, small animals may penetrate).
> > Or,
> > when using a pressure tight box, it must be stiff and sealed to
> > withstand under all
> > temperature conditions more then 1 bar/ 100 kPa. Do not forget that all
> > feed
> > throughs must be of real hermetic type, normal coaxial connectors are
> > not tight!
> > Don't route cables directly in, because no cable braid or mesh is vapor
> > tight.
> > _______________________________________________
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
>
>
>
>
> ------------------------------
>
> _______________________________________________
> time-nuts mailing list
> time-nuts@febo.com
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>
> End of time-nuts Digest, Vol 94, Issue 89
> *****************************************
>
TK
Tom Knox
Tue, May 15, 2012 2:02 AM
That sounds like what we use in the AeroSpace industry. I remember the UV dye.
Thanks
Thomas Knox
Date: Mon, 14 May 2012 21:13:55 -0400
From: sam.reaves@gmail.com
To: time-nuts@febo.com
Subject: Re: [time-nuts] Conformal Coating
For conformal coating I recommend Humiseal Acrylic 1B73 in aerosol. You can
also get it in brush form. I believe that Chemtronics used to offer acrylic
coating as well, maybe even re-packaging the Humiseal product. I don't know
if there is a source for small quantities of Humiseal but it is a fine
product.
I have also used Krylon clear acrylic that you can get at Wall-Mart in a
pinch. The acrylic coatings I have found are better for HiZ circuits that
have requirements for low-leakage. Consult the can for solvents and make
sure that what you are coating are compatible with Toluene, Ketones,
Acetone, etc. be careful around connectors as the coating will wick into
connectors as the 1B73 is a fairly low viscosity. You can also get Humiseal
formulations 1B38 and 1B66 which are also Acrylics but are brush on and
require a one gallon minimum purchase. The shipping cost for a gallon is
almost as much as the product due to the requirement that it be shipped as
a hazardous material (flameable). The acrylics can be dissolved with MEK or
any of the solvents I have listed above. You can remove a small amount with
a Q-Tip.
The Humiseal product also has a UV indicator in it that glows blue under a
black light so you can check coverage.
I have tested Humiseal Acrylic on probably 1000+ PCB's and it has yet to
fail me. It is also easy to rework and re-coat after repairs.
You can also get polyurethane coatings but I do not recommend them since
they are more difficult you use, not as easy to remove
and have better performance for HiZ and RF circuits.
Good luck and let us know how you make out.
Sam
W3OHM
http://www.hmcelectronics.com/product/Chemtronics/CTAR12
On Mon, May 14, 2012 at 7:31 PM, time-nuts-request@febo.com wrote:
Send time-nuts mailing list submissions to
time-nuts@febo.com
To subscribe or unsubscribe via the World Wide Web, visit
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
or, via email, send a message with subject or body 'help' to
time-nuts-request@febo.com
You can reach the person managing the list at
time-nuts-owner@febo.com
When replying, please edit your Subject line so it is more specific
than "Re: Contents of time-nuts digest..."
Today's Topics:
- Re: Why are 1PPS signals so skinny? (Jim Hickstein)
- Re: Why are 1PPS signals so skinny? (Azelio Boriani)
- Re: wwvb weak on east coast especially when the pre-amps
under wa... (Michael Blazer)
- Re: wwvb weak on east coast especially when the pre-amps
under wa... (Azelio Boriani)
- Re: Why are 1PPS signals so skinny? (Michael Blazer)
- Re: Why are 1PPS signals so skinny? (Bob Camp)
- Re: wwvb weak on east coast especially when thepre-amps under
wa... (Alan Melia)
Message: 1
Date: Mon, 14 May 2012 18:18:20 -0500
From: Jim Hickstein jxh@jxh.com
To: time-nuts@febo.com
Subject: Re: [time-nuts] Why are 1PPS signals so skinny?
Message-ID: 4FB192BC.4060801@jxh.com
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 2012/05/14 18:02, time-nuts-request@febo.com wrote:
military standards.
Hmm. Doesn't find MIL-TGDBP-41. I got this from my (now late) great
uncle, Bob
Sedgwick -- who was to hydraulics what I am to computers, only he has a
number
of patents.
Some smart-aleck at Wright Field, as it then was, put this on a drawing,
and it
went without comment for quite a while until someone tried to look it up.
This
escalated to a bird colonel, who then tracked down the miscreant.
It stands for Make It Like The G-D Blueprint For Once.
Message: 2
Date: Tue, 15 May 2012 01:21:26 +0200
From: Azelio Boriani azelio.boriani@screen.it
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Why are 1PPS signals so skinny?
Message-ID:
<CAL8XPmOc8cLJ3aGBcqJsJB=FbW5XTQ-_FY54R9edDUDUX+ADTg@mail.gmail.com
Content-Type: text/plain; charset=ISO-8859-1
Maybe the correct number is MIL-STD-188-115?
On Tue, May 15, 2012 at 1:18 AM, Jim Hickstein jxh@jxh.com wrote:
Hmm. Doesn't find MIL-TGDBP-41. I got this from my (now late) great
uncle, Bob Sedgwick -- who was to hydraulics what I am to computers, only
he has a number of patents.
Some smart-aleck at Wright Field, as it then was, put this on a drawing,
and it went without comment for quite a while until someone tried to look
it up. This escalated to a bird colonel, who then tracked down the
miscreant.
It stands for Make It Like The G-D Blueprint For Once.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
The other option of course is to pressurise the box with dry air to
a positive pressure differential, such that the net flow is always
at all points, but it's probably easier just to provide a drain hole:-)
However, whilst a drain hole will prevent the build up of a lake inside
enclosure it still doesn't prevent condensation forming on circuit
and powered circuit boards and condensation don't really go well
As per earlier comments, it's quite difficult to keep any externally
mounted enclosure totally moisture free, so it's much easier to accept
inevitable and allow for it.
In a past life I designed quite a few circuit boards that were required
be fitted in externally mounted vented enclosures, so not a great deal
pressurisation there then:-), and I usually specified that both sides
should be sprayed with a plastic coating following final test.
I can't remember now exactly what this stuff was called, but it was
readily available in the UK from both RS and Farnell as an aerosol
that provided a good barrier but was a bit more flexible than the usual
spec conformal coatings.
It melted easily under a soldering iron, albeit with a foul pong:-), so
reworking was no problem, and resisted moisture remarkably well.....
problem solved:-)
Nigel
GM8PZR
In a message dated 14/05/2012 23:10:30 GMT Daylight Time,
arnold.tibus@gmx.de writes:
The only solutions I think:
Apply air pressure tight boxes having a breathing hole an the bottom,
mount the
box that no rain and water can penetrate from the top or sides. If the
hole is big enough,
eg. 2mm, no pressure difference is possible and no pumping effect will
occur.
(If the hole is too wide, small animals may penetrate).
Or,
when using a pressure tight box, it must be stiff and sealed to
withstand under all
temperature conditions more then 1 bar/ 100 kPa. Do not forget that all
feed
throughs must be of real hermetic type, normal coaxial connectors are
not tight!
Don't route cables directly in, because no cable braid or mesh is vapor
tight.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
and follow the instructions there.
Content-Type: text/plain; charset=ISO-8859-1
We use the Plastik70 from Kontakt chemie
On Tue, May 15, 2012 at 1:23 AM, Michael Blazer mblazer@satx.rr.com
wrote:
The other option of course is to pressurise the box with dry air to
a positive pressure differential, such that the net flow is always
outwards
at all points, but it's probably easier just to provide a drain hole:-)
However, whilst a drain hole will prevent the build up of a lake inside
the
enclosure it still doesn't prevent condensation forming on circuit
boards,
and powered circuit boards and condensation don't really go well
together.
As per earlier comments, it's quite difficult to keep any externally
mounted enclosure totally moisture free, so it's much easier to accept
inevitable and allow for it.
In a past life I designed quite a few circuit boards that were required
to
be fitted in externally mounted vented enclosures, so not a great deal
pressurisation there then:-), and I usually specified that both sides
should be sprayed with a plastic coating following final test.
I can't remember now exactly what this stuff was called, but it was
readily available in the UK from both RS and Farnell as an aerosol
plastic spray
that provided a good barrier but was a bit more flexible than the usual
MOD
spec conformal coatings.
It melted easily under a soldering iron, albeit with a foul pong:-), so
reworking was no problem, and resisted moisture remarkably well.....
problem solved:-)
Nigel
GM8PZR
In a message dated 14/05/2012 23:10:30 GMT Daylight Time,
arnold.tibus@gmx.de writes:
The only solutions I think:
Apply air pressure tight boxes having a breathing hole an the bottom,
mount the
box that no rain and water can penetrate from the top or sides. If the
hole is big enough,
eg. 2mm, no pressure difference is possible and no pumping effect will
occur.
(If the hole is too wide, small animals may penetrate).
Or,
when using a pressure tight box, it must be stiff and sealed to
withstand under all
temperature conditions more then 1 bar/ 100 kPa. Do not forget that
feed
throughs must be of real hermetic type, normal coaxial connectors are
not tight!
Don't route cables directly in, because no cable braid or mesh is
Message: 5
Date: Mon, 14 May 2012 18:26:58 -0500
From: Michael Blazer mblazer@satx.rr.com
To: time-nuts@febo.com
Subject: Re: [time-nuts] Why are 1PPS signals so skinny?
Message-ID: 4FB194C2.6090401@satx.rr.com
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
I haven't heard that one before. I try to slip in the TLAR check in all
the test procedures I write. When 'they' ask, I look at it and say:
"That Looks About Right".
Mike
On 5/14/2012 6:18 PM, Jim Hickstein wrote:
Hmm. Doesn't find MIL-TGDBP-41. I got this from my (now late) great
uncle, Bob Sedgwick -- who was to hydraulics what I am to computers,
only he has a number of patents.
Some smart-aleck at Wright Field, as it then was, put this on a
drawing, and it went without comment for quite a while until someone
tried to look it up. This escalated to a bird colonel, who then
tracked down the miscreant.
It stands for Make It Like The G-D Blueprint For Once.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Message: 6
Date: Mon, 14 May 2012 19:30:49 -0400
From: Bob Camp lists@rtty.us
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Why are 1PPS signals so skinny?
Message-ID: 0CE3BEF7-A1BA-4CE1-8A74-3364B2A80302@rtty.us
Content-Type: text/plain; charset=iso-8859-1
Hi
I would bet that the basic electrical definition of the "skinny" PPS dates
at least to the mid 50's if not earlier.
Bob
On May 14, 2012, at 3:20 PM, Magnus Danielson wrote:
Mark& Azelio,
Or even 10V into 50ohm, 20us... See figure 3-4 in ICD-GPS-060.
http://www.navcen.uscg.gov/pdf/gps/ICD-GPS-060B.pdf
More modern 3-5.5V into 50ohm, 20us.
Above are two standards demanding short skinny 1PPS pulses. Are there
other standards with distinct shape requirements on 1PPS pulses?
You need to look at MIL STD 188/155 which if I recall things was
initially formed in the 60thies.
An AccuBeat presentation actually says that the PPS was originally
The MIL STD 188/155 is actually a 10 V peak level, so it was much hotter
than we are used to know. It specified 5 MHz as base frequency, or power of
2 multiples (10, 20, 40 MHz... ).
It was later reformulated in the PTTI spec, which ICD GPS 060 is a
derivate. The 50 ns rise and 1 us fall slopes comes from that spec.
I was not able to find MIL STD 188-155 on the net right now, but I have
been able to download it before, so if someone is a more lucky it should
surface. I should have my download somewhere.
and follow the instructions there.
Message: 7
Date: Tue, 15 May 2012 00:32:11 +0100
From: "Alan Melia" alan.melia@btinternet.com
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Subject: Re: [time-nuts] wwvb weak on east coast especially when
thepre-amps under wa...
Message-ID: 012501cd3229$cb66eae0$4001a8c0@lark
Content-Type: text/plain; charset="iso-8859-1"
Well almost Nigel, if you look at molecule mean velocities they are always
able to diffuse down a concentration gradient (i.e from wet into dry)
despite a small reverse presure gradient. It just takes longer under those
conditions :-))....which is often "enough"
Alan G3NYK
----- Original Message -----
From: GandalfG8@aol.com
To: time-nuts@febo.com
Sent: Tuesday, May 15, 2012 12:01 AM
Subject: Re: [time-nuts] wwvb weak on east coast especially when
thepre-amps
under wa...
The other option of course is to pressurise the box with dry air to
a positive pressure differential, such that the net flow is always
at all points, but it's probably easier just to provide a drain hole:-)
However, whilst a drain hole will prevent the build up of a lake inside
enclosure it still doesn't prevent condensation forming on circuit
and powered circuit boards and condensation don't really go well
As per earlier comments, it's quite difficult to keep any externally
mounted enclosure totally moisture free, so it's much easier to accept
inevitable and allow for it.
In a past life I designed quite a few circuit boards that were required
be fitted in externally mounted vented enclosures, so not a great deal
pressurisation there then:-), and I usually specified that both sides
should be sprayed with a plastic coating following final test.
I can't remember now exactly what this stuff was called, but it was
readily available in the UK from both RS and Farnell as an aerosol
that provided a good barrier but was a bit more flexible than the usual
spec conformal coatings.
It melted easily under a soldering iron, albeit with a foul pong:-), so
reworking was no problem, and resisted moisture remarkably well.....
problem solved:-)
Nigel
GM8PZR
In a message dated 14/05/2012 23:10:30 GMT Daylight Time,
arnold.tibus@gmx.de writes:
The only solutions I think:
Apply air pressure tight boxes having a breathing hole an the bottom,
mount the
box that no rain and water can penetrate from the top or sides. If the
hole is big enough,
eg. 2mm, no pressure difference is possible and no pumping effect will
occur.
(If the hole is too wide, small animals may penetrate).
Or,
when using a pressure tight box, it must be stiff and sealed to
withstand under all
temperature conditions more then 1 bar/ 100 kPa. Do not forget that all
feed
throughs must be of real hermetic type, normal coaxial connectors are
not tight!
Don't route cables directly in, because no cable braid or mesh is vapor
tight.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
and follow the instructions there.
That sounds like what we use in the AeroSpace industry. I remember the UV dye.
Thanks
Thomas Knox
> Date: Mon, 14 May 2012 21:13:55 -0400
> From: sam.reaves@gmail.com
> To: time-nuts@febo.com
> Subject: Re: [time-nuts] Conformal Coating
>
> For conformal coating I recommend Humiseal Acrylic 1B73 in aerosol. You can
> also get it in brush form. I believe that Chemtronics used to offer acrylic
> coating as well, maybe even re-packaging the Humiseal product. I don't know
> if there is a source for small quantities of Humiseal but it is a fine
> product.
>
> I have also used Krylon clear acrylic that you can get at Wall-Mart in a
> pinch. The acrylic coatings I have found are better for HiZ circuits that
> have requirements for low-leakage. Consult the can for solvents and make
> sure that what you are coating are compatible with Toluene, Ketones,
> Acetone, etc. be careful around connectors as the coating will wick into
> connectors as the 1B73 is a fairly low viscosity. You can also get Humiseal
> formulations 1B38 and 1B66 which are also Acrylics but are brush on and
> require a one gallon minimum purchase. The shipping cost for a gallon is
> almost as much as the product due to the requirement that it be shipped as
> a hazardous material (flameable). The acrylics can be dissolved with MEK or
> any of the solvents I have listed above. You can remove a small amount with
> a Q-Tip.
>
> The Humiseal product also has a UV indicator in it that glows blue under a
> black light so you can check coverage.
>
> I have tested Humiseal Acrylic on probably 1000+ PCB's and it has yet to
> fail me. It is also easy to rework and re-coat after repairs.
>
> You can also get polyurethane coatings but I do not recommend them since
> they are more difficult you use, not as easy to remove
> and have better performance for HiZ and RF circuits.
>
> Good luck and let us know how you make out.
>
> Sam
> W3OHM
>
> http://www.hmcelectronics.com/product/Chemtronics/CTAR12
>
>
>
>
> On Mon, May 14, 2012 at 7:31 PM, <time-nuts-request@febo.com> wrote:
>
> > Send time-nuts mailing list submissions to
> > time-nuts@febo.com
> >
> > To subscribe or unsubscribe via the World Wide Web, visit
> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > or, via email, send a message with subject or body 'help' to
> > time-nuts-request@febo.com
> >
> > You can reach the person managing the list at
> > time-nuts-owner@febo.com
> >
> > When replying, please edit your Subject line so it is more specific
> > than "Re: Contents of time-nuts digest..."
> >
> >
> > Today's Topics:
> >
> > 1. Re: Why are 1PPS signals so skinny? (Jim Hickstein)
> > 2. Re: Why are 1PPS signals so skinny? (Azelio Boriani)
> > 3. Re: wwvb weak on east coast especially when the pre-amps
> > under wa... (Michael Blazer)
> > 4. Re: wwvb weak on east coast especially when the pre-amps
> > under wa... (Azelio Boriani)
> > 5. Re: Why are 1PPS signals so skinny? (Michael Blazer)
> > 6. Re: Why are 1PPS signals so skinny? (Bob Camp)
> > 7. Re: wwvb weak on east coast especially when thepre-amps under
> > wa... (Alan Melia)
> >
> >
> > ----------------------------------------------------------------------
> >
> > Message: 1
> > Date: Mon, 14 May 2012 18:18:20 -0500
> > From: Jim Hickstein <jxh@jxh.com>
> > To: time-nuts@febo.com
> > Subject: Re: [time-nuts] Why are 1PPS signals so skinny?
> > Message-ID: <4FB192BC.4060801@jxh.com>
> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> >
> > On 2012/05/14 18:02, time-nuts-request@febo.com wrote:
> > > https://assist.daps.dla.mil/quicksearch/ is the search site for
> > military standards.
> >
> > Hmm. Doesn't find MIL-TGDBP-41. I got this from my (now late) great
> > uncle, Bob
> > Sedgwick -- who was to hydraulics what I am to computers, only he has a
> > number
> > of patents.
> >
> > Some smart-aleck at Wright Field, as it then was, put this on a drawing,
> > and it
> > went without comment for quite a while until someone tried to look it up.
> > This
> > escalated to a bird colonel, who then tracked down the miscreant.
> >
> > It stands for Make It Like The G-D Blueprint For Once.
> >
> >
> >
> > ------------------------------
> >
> > Message: 2
> > Date: Tue, 15 May 2012 01:21:26 +0200
> > From: Azelio Boriani <azelio.boriani@screen.it>
> > To: Discussion of precise time and frequency measurement
> > <time-nuts@febo.com>
> > Subject: Re: [time-nuts] Why are 1PPS signals so skinny?
> > Message-ID:
> > <CAL8XPmOc8cLJ3aGBcqJsJB=FbW5XTQ-_FY54R9edDUDUX+ADTg@mail.gmail.com
> > >
> > Content-Type: text/plain; charset=ISO-8859-1
> >
> > Maybe the correct number is MIL-STD-188-115?
> >
> > On Tue, May 15, 2012 at 1:18 AM, Jim Hickstein <jxh@jxh.com> wrote:
> >
> > > On 2012/05/14 18:02, time-nuts-request@febo.com wrote:
> > >
> > >> https://assist.daps.dla.mil/quicksearch/ is the search site for
> > >> military standards.
> > >>
> > >
> > > Hmm. Doesn't find MIL-TGDBP-41. I got this from my (now late) great
> > > uncle, Bob Sedgwick -- who was to hydraulics what I am to computers, only
> > > he has a number of patents.
> > >
> > > Some smart-aleck at Wright Field, as it then was, put this on a drawing,
> > > and it went without comment for quite a while until someone tried to look
> > > it up. This escalated to a bird colonel, who then tracked down the
> > > miscreant.
> > >
> > > It stands for Make It Like The G-D Blueprint For Once.
> > >
> > >
> > > _______________________________________________
> > > time-nuts mailing list -- time-nuts@febo.com
> > > To unsubscribe, go to
> > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > > and follow the instructions there.
> > >
> >
> >
> > ------------------------------
> >
> > Message: 3
> > Date: Mon, 14 May 2012 18:23:31 -0500
> > From: Michael Blazer <mblazer@satx.rr.com>
> > To: time-nuts@febo.com
> > Subject: Re: [time-nuts] wwvb weak on east coast especially when the
> > pre-amps under wa...
> > Message-ID: <4FB193F3.6000503@satx.rr.com>
> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> >
> > Here's comparison for various type of conformal coating:
> > http://mgchemicals.com/downloads/appguide/appguide0404.pdf.<
> > https://assist.daps.dla.mil/quicksearch/>
> >
> > I think there is a type that is 'serviceable' and removable with alcohol.
> >
> > Mike
> >
> > On 5/14/2012 6:01 PM, GandalfG8@aol.com wrote:
> > > The other option of course is to pressurise the box with dry air to
> > ensure
> > > a positive pressure differential, such that the net flow is always
> > outwards
> > > at all points, but it's probably easier just to provide a drain hole:-)
> > >
> > > However, whilst a drain hole will prevent the build up of a lake inside
> > the
> > > enclosure it still doesn't prevent condensation forming on circuit
> > boards,
> > > and powered circuit boards and condensation don't really go well
> > together.
> > >
> > > As per earlier comments, it's quite difficult to keep any externally
> > > mounted enclosure totally moisture free, so it's much easier to accept
> > the
> > > inevitable and allow for it.
> > >
> > > In a past life I designed quite a few circuit boards that were required
> > to
> > > be fitted in externally mounted vented enclosures, so not a great deal
> > of
> > > pressurisation there then:-), and I usually specified that both sides
> > > should be sprayed with a plastic coating following final test.
> > >
> > > I can't remember now exactly what this stuff was called, but it was
> > > readily available in the UK from both RS and Farnell as an aerosol
> > plastic spray
> > > that provided a good barrier but was a bit more flexible than the usual
> > MOD
> > > spec conformal coatings.
> > > It melted easily under a soldering iron, albeit with a foul pong:-), so
> > > reworking was no problem, and resisted moisture remarkably well.....
> > >
> > > problem solved:-)
> > >
> > > Nigel
> > > GM8PZR
> > >
> > >
> > >
> > >
> > >
> > > In a message dated 14/05/2012 23:10:30 GMT Daylight Time,
> > > arnold.tibus@gmx.de writes:
> > >
> > > The only solutions I think:
> > > Apply air pressure tight boxes having a breathing hole an the bottom,
> > > mount the
> > > box that no rain and water can penetrate from the top or sides. If the
> > > hole is big enough,
> > > eg. 2mm, no pressure difference is possible and no pumping effect will
> > > occur.
> > > (If the hole is too wide, small animals may penetrate).
> > > Or,
> > > when using a pressure tight box, it must be stiff and sealed to
> > > withstand under all
> > > temperature conditions more then 1 bar/ 100 kPa. Do not forget that all
> > > feed
> > > throughs must be of real hermetic type, normal coaxial connectors are
> > > not tight!
> > > Don't route cables directly in, because no cable braid or mesh is vapor
> > > tight.
> > > _______________________________________________
> > > time-nuts mailing list -- time-nuts@febo.com
> > > To unsubscribe, go to
> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > > and follow the instructions there.
> > >
> > >
> >
> >
> > ------------------------------
> >
> > Message: 4
> > Date: Tue, 15 May 2012 01:25:54 +0200
> > From: Azelio Boriani <azelio.boriani@screen.it>
> > To: Discussion of precise time and frequency measurement
> > <time-nuts@febo.com>
> > Subject: Re: [time-nuts] wwvb weak on east coast especially when the
> > pre-amps under wa...
> > Message-ID:
> > <CAL8XPmPCB-DWCpoT0NmfP+TdpdRcK-XjXxVJWyTJA+RQmux9dg@mail.gmail.com
> > >
> > Content-Type: text/plain; charset=ISO-8859-1
> >
> > We use the Plastik70 from Kontakt chemie
> >
> > On Tue, May 15, 2012 at 1:23 AM, Michael Blazer <mblazer@satx.rr.com>
> > wrote:
> >
> > > Here's comparison for various type of conformal coating:
> > > http://mgchemicals.com/downloads/appguide/appguide0404.pdf.<
> > > https://assist.daps.dla.mil/quicksearch/>
> > >
> > > I think there is a type that is 'serviceable' and removable with alcohol.
> > >
> > > Mike
> > >
> > >
> > > On 5/14/2012 6:01 PM, GandalfG8@aol.com wrote:
> > >
> > >> The other option of course is to pressurise the box with dry air to
> > ensure
> > >> a positive pressure differential, such that the net flow is always
> > >> outwards
> > >> at all points, but it's probably easier just to provide a drain hole:-)
> > >>
> > >> However, whilst a drain hole will prevent the build up of a lake inside
> > >> the
> > >> enclosure it still doesn't prevent condensation forming on circuit
> > >> boards,
> > >> and powered circuit boards and condensation don't really go well
> > >> together.
> > >>
> > >> As per earlier comments, it's quite difficult to keep any externally
> > >> mounted enclosure totally moisture free, so it's much easier to accept
> > the
> > >> inevitable and allow for it.
> > >>
> > >> In a past life I designed quite a few circuit boards that were required
> > >> to
> > >> be fitted in externally mounted vented enclosures, so not a great deal
> > of
> > >> pressurisation there then:-), and I usually specified that both sides
> > >> should be sprayed with a plastic coating following final test.
> > >>
> > >> I can't remember now exactly what this stuff was called, but it was
> > >> readily available in the UK from both RS and Farnell as an aerosol
> > >> plastic spray
> > >> that provided a good barrier but was a bit more flexible than the usual
> > >> MOD
> > >> spec conformal coatings.
> > >> It melted easily under a soldering iron, albeit with a foul pong:-), so
> > >> reworking was no problem, and resisted moisture remarkably well.....
> > >>
> > >> problem solved:-)
> > >>
> > >> Nigel
> > >> GM8PZR
> > >>
> > >>
> > >>
> > >>
> > >>
> > >> In a message dated 14/05/2012 23:10:30 GMT Daylight Time,
> > >> arnold.tibus@gmx.de writes:
> > >>
> > >> The only solutions I think:
> > >> Apply air pressure tight boxes having a breathing hole an the bottom,
> > >> mount the
> > >> box that no rain and water can penetrate from the top or sides. If the
> > >> hole is big enough,
> > >> eg. 2mm, no pressure difference is possible and no pumping effect will
> > >> occur.
> > >> (If the hole is too wide, small animals may penetrate).
> > >> Or,
> > >> when using a pressure tight box, it must be stiff and sealed to
> > >> withstand under all
> > >> temperature conditions more then 1 bar/ 100 kPa. Do not forget that
> > all
> > >> feed
> > >> throughs must be of real hermetic type, normal coaxial connectors are
> > >> not tight!
> > >> Don't route cables directly in, because no cable braid or mesh is
> > vapor
> > >> tight.
> > >> _______________________________________________
> > >> time-nuts mailing list -- time-nuts@febo.com
> > >> To unsubscribe, go to
> > >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > >> and follow the instructions there.
> > >>
> > >>
> > >> _______________________________________________
> > > time-nuts mailing list -- time-nuts@febo.com
> > > To unsubscribe, go to
> > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > > and follow the instructions there.
> > >
> >
> >
> > ------------------------------
> >
> > Message: 5
> > Date: Mon, 14 May 2012 18:26:58 -0500
> > From: Michael Blazer <mblazer@satx.rr.com>
> > To: time-nuts@febo.com
> > Subject: Re: [time-nuts] Why are 1PPS signals so skinny?
> > Message-ID: <4FB194C2.6090401@satx.rr.com>
> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> >
> > I haven't heard that one before. I try to slip in the TLAR check in all
> > the test procedures I write. When 'they' ask, I look at it and say:
> > "That Looks About Right".
> > Mike
> >
> > On 5/14/2012 6:18 PM, Jim Hickstein wrote:
> > > On 2012/05/14 18:02, time-nuts-request@febo.com wrote:
> > >> https://assist.daps.dla.mil/quicksearch/ is the search site for
> > >> military standards.
> > >
> > > Hmm. Doesn't find MIL-TGDBP-41. I got this from my (now late) great
> > > uncle, Bob Sedgwick -- who was to hydraulics what I am to computers,
> > > only he has a number of patents.
> > >
> > > Some smart-aleck at Wright Field, as it then was, put this on a
> > > drawing, and it went without comment for quite a while until someone
> > > tried to look it up. This escalated to a bird colonel, who then
> > > tracked down the miscreant.
> > >
> > > It stands for Make It Like The G-D Blueprint For Once.
> > >
> > > _______________________________________________
> > > time-nuts mailing list -- time-nuts@febo.com
> > > To unsubscribe, go to
> > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > > and follow the instructions there.
> > >
> > >
> >
> >
> >
> > ------------------------------
> >
> > Message: 6
> > Date: Mon, 14 May 2012 19:30:49 -0400
> > From: Bob Camp <lists@rtty.us>
> > To: Discussion of precise time and frequency measurement
> > <time-nuts@febo.com>
> > Subject: Re: [time-nuts] Why are 1PPS signals so skinny?
> > Message-ID: <0CE3BEF7-A1BA-4CE1-8A74-3364B2A80302@rtty.us>
> > Content-Type: text/plain; charset=iso-8859-1
> >
> > Hi
> >
> > I would bet that the basic electrical definition of the "skinny" PPS dates
> > at least to the mid 50's if not earlier.
> >
> > Bob
> >
> > On May 14, 2012, at 3:20 PM, Magnus Danielson wrote:
> >
> > > Mark, Azelio and Bj?rn,
> > >
> > > On 05/14/2012 06:33 PM, bg@lysator.liu.se wrote:
> > >> Mark& Azelio,
> > >>
> > >> Or even 10V into 50ohm, 20us... See figure 3-4 in ICD-GPS-060.
> > >>
> > >> http://www.navcen.uscg.gov/pdf/gps/ICD-GPS-060B.pdf
> > >>
> > >> More modern 3-5.5V into 50ohm, 20us.
> > >>
> > http://contracting.tacom.army.mil/majorsys/jab/DAGR%20Interface%20Specification.pdf
> > >>
> > >> Above are two standards demanding short skinny 1PPS pulses. Are there
> > any
> > >> other standards with distinct shape requirements on 1PPS pulses?
> > >
> > > You need to look at MIL STD 188/155 which if I recall things was
> > initially formed in the 60thies.
> > >
> > > An AccuBeat presentation actually says that the PPS was originally
> > defined in it.
> > >
> > > The MIL STD 188/155 is actually a 10 V peak level, so it was much hotter
> > than we are used to know. It specified 5 MHz as base frequency, or power of
> > 2 multiples (10, 20, 40 MHz... ).
> > >
> > > It was later reformulated in the PTTI spec, which ICD GPS 060 is a
> > derivate. The 50 ns rise and 1 us fall slopes comes from that spec.
> > >
> > > I was not able to find MIL STD 188-155 on the net right now, but I have
> > been able to download it before, so if someone is a more lucky it should
> > surface. I should have my download somewhere.
> > >
> > > Cheers,
> > > Magnus
> > >
> > > _______________________________________________
> > > time-nuts mailing list -- time-nuts@febo.com
> > > To unsubscribe, go to
> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > > and follow the instructions there.
> >
> >
> >
> >
> > ------------------------------
> >
> > Message: 7
> > Date: Tue, 15 May 2012 00:32:11 +0100
> > From: "Alan Melia" <alan.melia@btinternet.com>
> > To: "Discussion of precise time and frequency measurement"
> > <time-nuts@febo.com>
> > Subject: Re: [time-nuts] wwvb weak on east coast especially when
> > thepre-amps under wa...
> > Message-ID: <012501cd3229$cb66eae0$4001a8c0@lark>
> > Content-Type: text/plain; charset="iso-8859-1"
> >
> > Well almost Nigel, if you look at molecule mean velocities they are always
> > able to diffuse down a concentration gradient (i.e from wet into dry)
> > despite a small reverse presure gradient. It just takes longer under those
> > conditions :-))....which is often "enough"
> >
> > Alan G3NYK
> > ----- Original Message -----
> > From: <GandalfG8@aol.com>
> > To: <time-nuts@febo.com>
> > Sent: Tuesday, May 15, 2012 12:01 AM
> > Subject: Re: [time-nuts] wwvb weak on east coast especially when
> > thepre-amps
> > under wa...
> >
> >
> > > The other option of course is to pressurise the box with dry air to
> > ensure
> > > a positive pressure differential, such that the net flow is always
> > outwards
> > > at all points, but it's probably easier just to provide a drain hole:-)
> > >
> > > However, whilst a drain hole will prevent the build up of a lake inside
> > the
> > > enclosure it still doesn't prevent condensation forming on circuit
> > boards,
> > > and powered circuit boards and condensation don't really go well
> > together.
> > >
> > > As per earlier comments, it's quite difficult to keep any externally
> > > mounted enclosure totally moisture free, so it's much easier to accept
> > the
> > > inevitable and allow for it.
> > >
> > > In a past life I designed quite a few circuit boards that were required
> > to
> > > be fitted in externally mounted vented enclosures, so not a great deal
> > of
> > > pressurisation there then:-), and I usually specified that both sides
> > > should be sprayed with a plastic coating following final test.
> > >
> > > I can't remember now exactly what this stuff was called, but it was
> > > readily available in the UK from both RS and Farnell as an aerosol
> > plastic
> > spray
> > > that provided a good barrier but was a bit more flexible than the usual
> > MOD
> > > spec conformal coatings.
> > > It melted easily under a soldering iron, albeit with a foul pong:-), so
> > > reworking was no problem, and resisted moisture remarkably well.....
> > >
> > > problem solved:-)
> > >
> > > Nigel
> > > GM8PZR
> > >
> > >
> > >
> > >
> > >
> > > In a message dated 14/05/2012 23:10:30 GMT Daylight Time,
> > > arnold.tibus@gmx.de writes:
> > >
> > > The only solutions I think:
> > > Apply air pressure tight boxes having a breathing hole an the bottom,
> > > mount the
> > > box that no rain and water can penetrate from the top or sides. If the
> > > hole is big enough,
> > > eg. 2mm, no pressure difference is possible and no pumping effect will
> > > occur.
> > > (If the hole is too wide, small animals may penetrate).
> > > Or,
> > > when using a pressure tight box, it must be stiff and sealed to
> > > withstand under all
> > > temperature conditions more then 1 bar/ 100 kPa. Do not forget that all
> > > feed
> > > throughs must be of real hermetic type, normal coaxial connectors are
> > > not tight!
> > > Don't route cables directly in, because no cable braid or mesh is vapor
> > > tight.
> > > _______________________________________________
> > > time-nuts mailing list -- time-nuts@febo.com
> > > To unsubscribe, go to
> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > > and follow the instructions there.
> >
> >
> >
> >
> > ------------------------------
> >
> > _______________________________________________
> > time-nuts mailing list
> > time-nuts@febo.com
> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> >
> > End of time-nuts Digest, Vol 94, Issue 89
> > *****************************************
> >
> _______________________________________________
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
MB
Michael Blazer
Tue, May 15, 2012 2:51 AM
The Humiseal and Chemtronics Acrylic both meet the Mil Spec 'AR' rating.
(I've had to track down this document trail.) I believe the MG
Chemicals also meets the same spec. The MG and Chemtronics are readily
available at most local electronic stores, Newark, Mouser and other
distributors.
Mike
On 5/14/2012 8:13 PM, Sam Reaves wrote:
For conformal coating I recommend Humiseal Acrylic 1B73 in aerosol. You can
also get it in brush form. I believe that Chemtronics used to offer acrylic
coating as well, maybe even re-packaging the Humiseal product. I don't know
if there is a source for small quantities of Humiseal but it is a fine
product.
I have also used Krylon clear acrylic that you can get at Wall-Mart in a
pinch. The acrylic coatings I have found are better for HiZ circuits that
have requirements for low-leakage. Consult the can for solvents and make
sure that what you are coating are compatible with Toluene, Ketones,
Acetone, etc. be careful around connectors as the coating will wick into
connectors as the 1B73 is a fairly low viscosity. You can also get Humiseal
formulations 1B38 and 1B66 which are also Acrylics but are brush on and
require a one gallon minimum purchase. The shipping cost for a gallon is
almost as much as the product due to the requirement that it be shipped as
a hazardous material (flameable). The acrylics can be dissolved with MEK or
any of the solvents I have listed above. You can remove a small amount with
a Q-Tip.
The Humiseal product also has a UV indicator in it that glows blue under a
black light so you can check coverage.
I have tested Humiseal Acrylic on probably 1000+ PCB's and it has yet to
fail me. It is also easy to rework and re-coat after repairs.
You can also get polyurethane coatings but I do not recommend them since
they are more difficult you use, not as easy to remove
and have better performance for HiZ and RF circuits.
Good luck and let us know how you make out.
Sam
W3OHM
http://www.hmcelectronics.com/product/Chemtronics/CTAR12
On Mon, May 14, 2012 at 7:31 PM,time-nuts-request@febo.com wrote:
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Today's Topics:
1. Re: Why are 1PPS signals so skinny? (Jim Hickstein)
2. Re: Why are 1PPS signals so skinny? (Azelio Boriani)
3. Re: wwvb weak on east coast especially when the pre-amps
under wa... (Michael Blazer)
4. Re: wwvb weak on east coast especially when the pre-amps
under wa... (Azelio Boriani)
5. Re: Why are 1PPS signals so skinny? (Michael Blazer)
6. Re: Why are 1PPS signals so skinny? (Bob Camp)
7. Re: wwvb weak on east coast especially when thepre-amps under
wa... (Alan Melia)
Message: 1
Date: Mon, 14 May 2012 18:18:20 -0500
From: Jim Hicksteinjxh@jxh.com
To: time-nuts@febo.com
Subject: Re: [time-nuts] Why are 1PPS signals so skinny?
Message-ID:4FB192BC.4060801@jxh.com
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 2012/05/14 18:02, time-nuts-request@febo.com wrote:
military standards.
Hmm. Doesn't find MIL-TGDBP-41. I got this from my (now late) great
uncle, Bob
Sedgwick -- who was to hydraulics what I am to computers, only he has a
number
of patents.
Some smart-aleck at Wright Field, as it then was, put this on a drawing,
and it
went without comment for quite a while until someone tried to look it up.
This
escalated to a bird colonel, who then tracked down the miscreant.
It stands for Make It Like The G-D Blueprint For Once.
Message: 2
Date: Tue, 15 May 2012 01:21:26 +0200
From: Azelio Borianiazelio.boriani@screen.it
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Why are 1PPS signals so skinny?
Message-ID:
<CAL8XPmOc8cLJ3aGBcqJsJB=FbW5XTQ-_FY54R9edDUDUX+ADTg@mail.gmail.com
Content-Type: text/plain; charset=ISO-8859-1
Maybe the correct number is MIL-STD-188-115?
On Tue, May 15, 2012 at 1:18 AM, Jim Hicksteinjxh@jxh.com wrote:
Hmm. Doesn't find MIL-TGDBP-41. I got this from my (now late) great
uncle, Bob Sedgwick -- who was to hydraulics what I am to computers, only
he has a number of patents.
Some smart-aleck at Wright Field, as it then was, put this on a drawing,
and it went without comment for quite a while until someone tried to look
it up. This escalated to a bird colonel, who then tracked down the
miscreant.
It stands for Make It Like The G-D Blueprint For Once.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
The other option of course is to pressurise the box with dry air to
a positive pressure differential, such that the net flow is always
at all points, but it's probably easier just to provide a drain hole:-)
However, whilst a drain hole will prevent the build up of a lake inside
enclosure it still doesn't prevent condensation forming on circuit
and powered circuit boards and condensation don't really go well
As per earlier comments, it's quite difficult to keep any externally
mounted enclosure totally moisture free, so it's much easier to accept
inevitable and allow for it.
In a past life I designed quite a few circuit boards that were required
be fitted in externally mounted vented enclosures, so not a great deal
pressurisation there then:-), and I usually specified that both sides
should be sprayed with a plastic coating following final test.
I can't remember now exactly what this stuff was called, but it was
readily available in the UK from both RS and Farnell as an aerosol
that provided a good barrier but was a bit more flexible than the usual
spec conformal coatings.
It melted easily under a soldering iron, albeit with a foul pong:-), so
reworking was no problem, and resisted moisture remarkably well.....
problem solved:-)
Nigel
GM8PZR
In a message dated 14/05/2012 23:10:30 GMT Daylight Time,
arnold.tibus@gmx.de writes:
The only solutions I think:
Apply air pressure tight boxes having a breathing hole an the bottom,
mount the
box that no rain and water can penetrate from the top or sides. If the
hole is big enough,
eg. 2mm, no pressure difference is possible and no pumping effect will
occur.
(If the hole is too wide, small animals may penetrate).
Or,
when using a pressure tight box, it must be stiff and sealed to
withstand under all
temperature conditions more then 1 bar/ 100 kPa. Do not forget that all
feed
throughs must be of real hermetic type, normal coaxial connectors are
not tight!
Don't route cables directly in, because no cable braid or mesh is vapor
tight.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
and follow the instructions there.
The other option of course is to pressurise the box with dry air to
a positive pressure differential, such that the net flow is always
outwards
at all points, but it's probably easier just to provide a drain hole:-)
However, whilst a drain hole will prevent the build up of a lake inside
the
enclosure it still doesn't prevent condensation forming on circuit
boards,
and powered circuit boards and condensation don't really go well
together.
As per earlier comments, it's quite difficult to keep any externally
mounted enclosure totally moisture free, so it's much easier to accept
inevitable and allow for it.
In a past life I designed quite a few circuit boards that were required
to
be fitted in externally mounted vented enclosures, so not a great deal
pressurisation there then:-), and I usually specified that both sides
should be sprayed with a plastic coating following final test.
I can't remember now exactly what this stuff was called, but it was
readily available in the UK from both RS and Farnell as an aerosol
plastic spray
that provided a good barrier but was a bit more flexible than the usual
MOD
spec conformal coatings.
It melted easily under a soldering iron, albeit with a foul pong:-), so
reworking was no problem, and resisted moisture remarkably well.....
problem solved:-)
Nigel
GM8PZR
In a message dated 14/05/2012 23:10:30 GMT Daylight Time,
arnold.tibus@gmx.de writes:
The only solutions I think:
Apply air pressure tight boxes having a breathing hole an the bottom,
mount the
box that no rain and water can penetrate from the top or sides. If the
hole is big enough,
eg. 2mm, no pressure difference is possible and no pumping effect will
occur.
(If the hole is too wide, small animals may penetrate).
Or,
when using a pressure tight box, it must be stiff and sealed to
withstand under all
temperature conditions more then 1 bar/ 100 kPa. Do not forget that
feed
throughs must be of real hermetic type, normal coaxial connectors are
not tight!
Don't route cables directly in, because no cable braid or mesh is
Message: 5
Date: Mon, 14 May 2012 18:26:58 -0500
From: Michael Blazermblazer@satx.rr.com
To: time-nuts@febo.com
Subject: Re: [time-nuts] Why are 1PPS signals so skinny?
Message-ID:4FB194C2.6090401@satx.rr.com
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
I haven't heard that one before. I try to slip in the TLAR check in all
the test procedures I write. When 'they' ask, I look at it and say:
"That Looks About Right".
Mike
On 5/14/2012 6:18 PM, Jim Hickstein wrote:
Hmm. Doesn't find MIL-TGDBP-41. I got this from my (now late) great
uncle, Bob Sedgwick -- who was to hydraulics what I am to computers,
only he has a number of patents.
Some smart-aleck at Wright Field, as it then was, put this on a
drawing, and it went without comment for quite a while until someone
tried to look it up. This escalated to a bird colonel, who then
tracked down the miscreant.
It stands for Make It Like The G-D Blueprint For Once.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Message: 6
Date: Mon, 14 May 2012 19:30:49 -0400
From: Bob Camplists@rtty.us
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Why are 1PPS signals so skinny?
Message-ID:0CE3BEF7-A1BA-4CE1-8A74-3364B2A80302@rtty.us
Content-Type: text/plain; charset=iso-8859-1
Hi
I would bet that the basic electrical definition of the "skinny" PPS dates
at least to the mid 50's if not earlier.
Bob
On May 14, 2012, at 3:20 PM, Magnus Danielson wrote:
Mark& Azelio,
Or even 10V into 50ohm, 20us... See figure 3-4 in ICD-GPS-060.
http://www.navcen.uscg.gov/pdf/gps/ICD-GPS-060B.pdf
More modern 3-5.5V into 50ohm, 20us.
Above are two standards demanding short skinny 1PPS pulses. Are there
other standards with distinct shape requirements on 1PPS pulses?
You need to look at MIL STD 188/155 which if I recall things was
initially formed in the 60thies.
An AccuBeat presentation actually says that the PPS was originally
The MIL STD 188/155 is actually a 10 V peak level, so it was much hotter
than we are used to know. It specified 5 MHz as base frequency, or power of
2 multiples (10, 20, 40 MHz... ).
It was later reformulated in the PTTI spec, which ICD GPS 060 is a
derivate. The 50 ns rise and 1 us fall slopes comes from that spec.
I was not able to find MIL STD 188-155 on the net right now, but I have
been able to download it before, so if someone is a more lucky it should
surface. I should have my download somewhere.
and follow the instructions there.
Message: 7
Date: Tue, 15 May 2012 00:32:11 +0100
From: "Alan Melia"alan.melia@btinternet.com
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Subject: Re: [time-nuts] wwvb weak on east coast especially when
thepre-amps under wa...
Message-ID:012501cd3229$cb66eae0$4001a8c0@lark
Content-Type: text/plain; charset="iso-8859-1"
Well almost Nigel, if you look at molecule mean velocities they are always
able to diffuse down a concentration gradient (i.e from wet into dry)
despite a small reverse presure gradient. It just takes longer under those
conditions :-))....which is often "enough"
Alan G3NYK
----- Original Message -----
From:GandalfG8@aol.com
To:time-nuts@febo.com
Sent: Tuesday, May 15, 2012 12:01 AM
Subject: Re: [time-nuts] wwvb weak on east coast especially when
thepre-amps
under wa...
The other option of course is to pressurise the box with dry air to
a positive pressure differential, such that the net flow is always
at all points, but it's probably easier just to provide a drain hole:-)
However, whilst a drain hole will prevent the build up of a lake inside
enclosure it still doesn't prevent condensation forming on circuit
and powered circuit boards and condensation don't really go well
As per earlier comments, it's quite difficult to keep any externally
mounted enclosure totally moisture free, so it's much easier to accept
inevitable and allow for it.
In a past life I designed quite a few circuit boards that were required
be fitted in externally mounted vented enclosures, so not a great deal
pressurisation there then:-), and I usually specified that both sides
should be sprayed with a plastic coating following final test.
I can't remember now exactly what this stuff was called, but it was
readily available in the UK from both RS and Farnell as an aerosol
that provided a good barrier but was a bit more flexible than the usual
spec conformal coatings.
It melted easily under a soldering iron, albeit with a foul pong:-), so
reworking was no problem, and resisted moisture remarkably well.....
problem solved:-)
Nigel
GM8PZR
In a message dated 14/05/2012 23:10:30 GMT Daylight Time,
arnold.tibus@gmx.de writes:
The only solutions I think:
Apply air pressure tight boxes having a breathing hole an the bottom,
mount the
box that no rain and water can penetrate from the top or sides. If the
hole is big enough,
eg. 2mm, no pressure difference is possible and no pumping effect will
occur.
(If the hole is too wide, small animals may penetrate).
Or,
when using a pressure tight box, it must be stiff and sealed to
withstand under all
temperature conditions more then 1 bar/ 100 kPa. Do not forget that all
feed
throughs must be of real hermetic type, normal coaxial connectors are
not tight!
Don't route cables directly in, because no cable braid or mesh is vapor
tight.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
and follow the instructions there.
The Humiseal and Chemtronics Acrylic both meet the Mil Spec 'AR' rating.
(I've had to track down this document trail.) I believe the MG
Chemicals also meets the same spec. The MG and Chemtronics are readily
available at most local electronic stores, Newark, Mouser and other
distributors.
Mike
On 5/14/2012 8:13 PM, Sam Reaves wrote:
> For conformal coating I recommend Humiseal Acrylic 1B73 in aerosol. You can
> also get it in brush form. I believe that Chemtronics used to offer acrylic
> coating as well, maybe even re-packaging the Humiseal product. I don't know
> if there is a source for small quantities of Humiseal but it is a fine
> product.
>
> I have also used Krylon clear acrylic that you can get at Wall-Mart in a
> pinch. The acrylic coatings I have found are better for HiZ circuits that
> have requirements for low-leakage. Consult the can for solvents and make
> sure that what you are coating are compatible with Toluene, Ketones,
> Acetone, etc. be careful around connectors as the coating will wick into
> connectors as the 1B73 is a fairly low viscosity. You can also get Humiseal
> formulations 1B38 and 1B66 which are also Acrylics but are brush on and
> require a one gallon minimum purchase. The shipping cost for a gallon is
> almost as much as the product due to the requirement that it be shipped as
> a hazardous material (flameable). The acrylics can be dissolved with MEK or
> any of the solvents I have listed above. You can remove a small amount with
> a Q-Tip.
>
> The Humiseal product also has a UV indicator in it that glows blue under a
> black light so you can check coverage.
>
> I have tested Humiseal Acrylic on probably 1000+ PCB's and it has yet to
> fail me. It is also easy to rework and re-coat after repairs.
>
> You can also get polyurethane coatings but I do not recommend them since
> they are more difficult you use, not as easy to remove
> and have better performance for HiZ and RF circuits.
>
> Good luck and let us know how you make out.
>
> Sam
> W3OHM
>
> http://www.hmcelectronics.com/product/Chemtronics/CTAR12
>
>
>
>
> On Mon, May 14, 2012 at 7:31 PM,<time-nuts-request@febo.com> wrote:
>
>> Send time-nuts mailing list submissions to
>> time-nuts@febo.com
>>
>> To subscribe or unsubscribe via the World Wide Web, visit
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> or, via email, send a message with subject or body 'help' to
>> time-nuts-request@febo.com
>>
>> You can reach the person managing the list at
>> time-nuts-owner@febo.com
>>
>> When replying, please edit your Subject line so it is more specific
>> than "Re: Contents of time-nuts digest..."
>>
>>
>> Today's Topics:
>>
>> 1. Re: Why are 1PPS signals so skinny? (Jim Hickstein)
>> 2. Re: Why are 1PPS signals so skinny? (Azelio Boriani)
>> 3. Re: wwvb weak on east coast especially when the pre-amps
>> under wa... (Michael Blazer)
>> 4. Re: wwvb weak on east coast especially when the pre-amps
>> under wa... (Azelio Boriani)
>> 5. Re: Why are 1PPS signals so skinny? (Michael Blazer)
>> 6. Re: Why are 1PPS signals so skinny? (Bob Camp)
>> 7. Re: wwvb weak on east coast especially when thepre-amps under
>> wa... (Alan Melia)
>>
>>
>> ----------------------------------------------------------------------
>>
>> Message: 1
>> Date: Mon, 14 May 2012 18:18:20 -0500
>> From: Jim Hickstein<jxh@jxh.com>
>> To: time-nuts@febo.com
>> Subject: Re: [time-nuts] Why are 1PPS signals so skinny?
>> Message-ID:<4FB192BC.4060801@jxh.com>
>> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>>
>> On 2012/05/14 18:02, time-nuts-request@febo.com wrote:
>>> https://assist.daps.dla.mil/quicksearch/ is the search site for
>> military standards.
>>
>> Hmm. Doesn't find MIL-TGDBP-41. I got this from my (now late) great
>> uncle, Bob
>> Sedgwick -- who was to hydraulics what I am to computers, only he has a
>> number
>> of patents.
>>
>> Some smart-aleck at Wright Field, as it then was, put this on a drawing,
>> and it
>> went without comment for quite a while until someone tried to look it up.
>> This
>> escalated to a bird colonel, who then tracked down the miscreant.
>>
>> It stands for Make It Like The G-D Blueprint For Once.
>>
>>
>>
>> ------------------------------
>>
>> Message: 2
>> Date: Tue, 15 May 2012 01:21:26 +0200
>> From: Azelio Boriani<azelio.boriani@screen.it>
>> To: Discussion of precise time and frequency measurement
>> <time-nuts@febo.com>
>> Subject: Re: [time-nuts] Why are 1PPS signals so skinny?
>> Message-ID:
>> <CAL8XPmOc8cLJ3aGBcqJsJB=FbW5XTQ-_FY54R9edDUDUX+ADTg@mail.gmail.com
>> Content-Type: text/plain; charset=ISO-8859-1
>>
>> Maybe the correct number is MIL-STD-188-115?
>>
>> On Tue, May 15, 2012 at 1:18 AM, Jim Hickstein<jxh@jxh.com> wrote:
>>
>>> On 2012/05/14 18:02, time-nuts-request@febo.com wrote:
>>>
>>>> https://assist.daps.dla.mil/quicksearch/ is the search site for
>>>> military standards.
>>>>
>>> Hmm. Doesn't find MIL-TGDBP-41. I got this from my (now late) great
>>> uncle, Bob Sedgwick -- who was to hydraulics what I am to computers, only
>>> he has a number of patents.
>>>
>>> Some smart-aleck at Wright Field, as it then was, put this on a drawing,
>>> and it went without comment for quite a while until someone tried to look
>>> it up. This escalated to a bird colonel, who then tracked down the
>>> miscreant.
>>>
>>> It stands for Make It Like The G-D Blueprint For Once.
>>>
>>>
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts@febo.com
>>> To unsubscribe, go to
>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>>>
>>
>> ------------------------------
>>
>> Message: 3
>> Date: Mon, 14 May 2012 18:23:31 -0500
>> From: Michael Blazer<mblazer@satx.rr.com>
>> To: time-nuts@febo.com
>> Subject: Re: [time-nuts] wwvb weak on east coast especially when the
>> pre-amps under wa...
>> Message-ID:<4FB193F3.6000503@satx.rr.com>
>> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>>
>> Here's comparison for various type of conformal coating:
>> http://mgchemicals.com/downloads/appguide/appguide0404.pdf.<
>> https://assist.daps.dla.mil/quicksearch/>
>>
>> I think there is a type that is 'serviceable' and removable with alcohol.
>>
>> Mike
>>
>> On 5/14/2012 6:01 PM, GandalfG8@aol.com wrote:
>>> The other option of course is to pressurise the box with dry air to
>> ensure
>>> a positive pressure differential, such that the net flow is always
>> outwards
>>> at all points, but it's probably easier just to provide a drain hole:-)
>>>
>>> However, whilst a drain hole will prevent the build up of a lake inside
>> the
>>> enclosure it still doesn't prevent condensation forming on circuit
>> boards,
>>> and powered circuit boards and condensation don't really go well
>> together.
>>> As per earlier comments, it's quite difficult to keep any externally
>>> mounted enclosure totally moisture free, so it's much easier to accept
>> the
>>> inevitable and allow for it.
>>>
>>> In a past life I designed quite a few circuit boards that were required
>> to
>>> be fitted in externally mounted vented enclosures, so not a great deal
>> of
>>> pressurisation there then:-), and I usually specified that both sides
>>> should be sprayed with a plastic coating following final test.
>>>
>>> I can't remember now exactly what this stuff was called, but it was
>>> readily available in the UK from both RS and Farnell as an aerosol
>> plastic spray
>>> that provided a good barrier but was a bit more flexible than the usual
>> MOD
>>> spec conformal coatings.
>>> It melted easily under a soldering iron, albeit with a foul pong:-), so
>>> reworking was no problem, and resisted moisture remarkably well.....
>>>
>>> problem solved:-)
>>>
>>> Nigel
>>> GM8PZR
>>>
>>>
>>>
>>>
>>>
>>> In a message dated 14/05/2012 23:10:30 GMT Daylight Time,
>>> arnold.tibus@gmx.de writes:
>>>
>>> The only solutions I think:
>>> Apply air pressure tight boxes having a breathing hole an the bottom,
>>> mount the
>>> box that no rain and water can penetrate from the top or sides. If the
>>> hole is big enough,
>>> eg. 2mm, no pressure difference is possible and no pumping effect will
>>> occur.
>>> (If the hole is too wide, small animals may penetrate).
>>> Or,
>>> when using a pressure tight box, it must be stiff and sealed to
>>> withstand under all
>>> temperature conditions more then 1 bar/ 100 kPa. Do not forget that all
>>> feed
>>> throughs must be of real hermetic type, normal coaxial connectors are
>>> not tight!
>>> Don't route cables directly in, because no cable braid or mesh is vapor
>>> tight.
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts@febo.com
>>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>>>
>>>
>>
>> ------------------------------
>>
>> Message: 4
>> Date: Tue, 15 May 2012 01:25:54 +0200
>> From: Azelio Boriani<azelio.boriani@screen.it>
>> To: Discussion of precise time and frequency measurement
>> <time-nuts@febo.com>
>> Subject: Re: [time-nuts] wwvb weak on east coast especially when the
>> pre-amps under wa...
>> Message-ID:
>> <CAL8XPmPCB-DWCpoT0NmfP+TdpdRcK-XjXxVJWyTJA+RQmux9dg@mail.gmail.com
>> Content-Type: text/plain; charset=ISO-8859-1
>>
>> We use the Plastik70 from Kontakt chemie
>>
>> On Tue, May 15, 2012 at 1:23 AM, Michael Blazer<mblazer@satx.rr.com>
>> wrote:
>>
>>> Here's comparison for various type of conformal coating:
>>> http://mgchemicals.com/downloads/appguide/appguide0404.pdf.<
>>> https://assist.daps.dla.mil/quicksearch/>
>>>
>>> I think there is a type that is 'serviceable' and removable with alcohol.
>>>
>>> Mike
>>>
>>>
>>> On 5/14/2012 6:01 PM, GandalfG8@aol.com wrote:
>>>
>>>> The other option of course is to pressurise the box with dry air to
>> ensure
>>>> a positive pressure differential, such that the net flow is always
>>>> outwards
>>>> at all points, but it's probably easier just to provide a drain hole:-)
>>>>
>>>> However, whilst a drain hole will prevent the build up of a lake inside
>>>> the
>>>> enclosure it still doesn't prevent condensation forming on circuit
>>>> boards,
>>>> and powered circuit boards and condensation don't really go well
>>>> together.
>>>>
>>>> As per earlier comments, it's quite difficult to keep any externally
>>>> mounted enclosure totally moisture free, so it's much easier to accept
>> the
>>>> inevitable and allow for it.
>>>>
>>>> In a past life I designed quite a few circuit boards that were required
>>>> to
>>>> be fitted in externally mounted vented enclosures, so not a great deal
>> of
>>>> pressurisation there then:-), and I usually specified that both sides
>>>> should be sprayed with a plastic coating following final test.
>>>>
>>>> I can't remember now exactly what this stuff was called, but it was
>>>> readily available in the UK from both RS and Farnell as an aerosol
>>>> plastic spray
>>>> that provided a good barrier but was a bit more flexible than the usual
>>>> MOD
>>>> spec conformal coatings.
>>>> It melted easily under a soldering iron, albeit with a foul pong:-), so
>>>> reworking was no problem, and resisted moisture remarkably well.....
>>>>
>>>> problem solved:-)
>>>>
>>>> Nigel
>>>> GM8PZR
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> In a message dated 14/05/2012 23:10:30 GMT Daylight Time,
>>>> arnold.tibus@gmx.de writes:
>>>>
>>>> The only solutions I think:
>>>> Apply air pressure tight boxes having a breathing hole an the bottom,
>>>> mount the
>>>> box that no rain and water can penetrate from the top or sides. If the
>>>> hole is big enough,
>>>> eg. 2mm, no pressure difference is possible and no pumping effect will
>>>> occur.
>>>> (If the hole is too wide, small animals may penetrate).
>>>> Or,
>>>> when using a pressure tight box, it must be stiff and sealed to
>>>> withstand under all
>>>> temperature conditions more then 1 bar/ 100 kPa. Do not forget that
>> all
>>>> feed
>>>> throughs must be of real hermetic type, normal coaxial connectors are
>>>> not tight!
>>>> Don't route cables directly in, because no cable braid or mesh is
>> vapor
>>>> tight.
>>>> _______________________________________________
>>>> time-nuts mailing list -- time-nuts@febo.com
>>>> To unsubscribe, go to
>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>>> and follow the instructions there.
>>>>
>>>>
>>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts@febo.com
>>> To unsubscribe, go to
>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>>>
>>
>> ------------------------------
>>
>> Message: 5
>> Date: Mon, 14 May 2012 18:26:58 -0500
>> From: Michael Blazer<mblazer@satx.rr.com>
>> To: time-nuts@febo.com
>> Subject: Re: [time-nuts] Why are 1PPS signals so skinny?
>> Message-ID:<4FB194C2.6090401@satx.rr.com>
>> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>>
>> I haven't heard that one before. I try to slip in the TLAR check in all
>> the test procedures I write. When 'they' ask, I look at it and say:
>> "That Looks About Right".
>> Mike
>>
>> On 5/14/2012 6:18 PM, Jim Hickstein wrote:
>>> On 2012/05/14 18:02, time-nuts-request@febo.com wrote:
>>>> https://assist.daps.dla.mil/quicksearch/ is the search site for
>>>> military standards.
>>> Hmm. Doesn't find MIL-TGDBP-41. I got this from my (now late) great
>>> uncle, Bob Sedgwick -- who was to hydraulics what I am to computers,
>>> only he has a number of patents.
>>>
>>> Some smart-aleck at Wright Field, as it then was, put this on a
>>> drawing, and it went without comment for quite a while until someone
>>> tried to look it up. This escalated to a bird colonel, who then
>>> tracked down the miscreant.
>>>
>>> It stands for Make It Like The G-D Blueprint For Once.
>>>
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts@febo.com
>>> To unsubscribe, go to
>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>>>
>>>
>>
>>
>> ------------------------------
>>
>> Message: 6
>> Date: Mon, 14 May 2012 19:30:49 -0400
>> From: Bob Camp<lists@rtty.us>
>> To: Discussion of precise time and frequency measurement
>> <time-nuts@febo.com>
>> Subject: Re: [time-nuts] Why are 1PPS signals so skinny?
>> Message-ID:<0CE3BEF7-A1BA-4CE1-8A74-3364B2A80302@rtty.us>
>> Content-Type: text/plain; charset=iso-8859-1
>>
>> Hi
>>
>> I would bet that the basic electrical definition of the "skinny" PPS dates
>> at least to the mid 50's if not earlier.
>>
>> Bob
>>
>> On May 14, 2012, at 3:20 PM, Magnus Danielson wrote:
>>
>>> Mark, Azelio and Bj?rn,
>>>
>>> On 05/14/2012 06:33 PM, bg@lysator.liu.se wrote:
>>>> Mark& Azelio,
>>>>
>>>> Or even 10V into 50ohm, 20us... See figure 3-4 in ICD-GPS-060.
>>>>
>>>> http://www.navcen.uscg.gov/pdf/gps/ICD-GPS-060B.pdf
>>>>
>>>> More modern 3-5.5V into 50ohm, 20us.
>>>>
>> http://contracting.tacom.army.mil/majorsys/jab/DAGR%20Interface%20Specification.pdf
>>>> Above are two standards demanding short skinny 1PPS pulses. Are there
>> any
>>>> other standards with distinct shape requirements on 1PPS pulses?
>>> You need to look at MIL STD 188/155 which if I recall things was
>> initially formed in the 60thies.
>>> An AccuBeat presentation actually says that the PPS was originally
>> defined in it.
>>> The MIL STD 188/155 is actually a 10 V peak level, so it was much hotter
>> than we are used to know. It specified 5 MHz as base frequency, or power of
>> 2 multiples (10, 20, 40 MHz... ).
>>> It was later reformulated in the PTTI spec, which ICD GPS 060 is a
>> derivate. The 50 ns rise and 1 us fall slopes comes from that spec.
>>> I was not able to find MIL STD 188-155 on the net right now, but I have
>> been able to download it before, so if someone is a more lucky it should
>> surface. I should have my download somewhere.
>>> Cheers,
>>> Magnus
>>>
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts@febo.com
>>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>>
>>
>>
>> ------------------------------
>>
>> Message: 7
>> Date: Tue, 15 May 2012 00:32:11 +0100
>> From: "Alan Melia"<alan.melia@btinternet.com>
>> To: "Discussion of precise time and frequency measurement"
>> <time-nuts@febo.com>
>> Subject: Re: [time-nuts] wwvb weak on east coast especially when
>> thepre-amps under wa...
>> Message-ID:<012501cd3229$cb66eae0$4001a8c0@lark>
>> Content-Type: text/plain; charset="iso-8859-1"
>>
>> Well almost Nigel, if you look at molecule mean velocities they are always
>> able to diffuse down a concentration gradient (i.e from wet into dry)
>> despite a small reverse presure gradient. It just takes longer under those
>> conditions :-))....which is often "enough"
>>
>> Alan G3NYK
>> ----- Original Message -----
>> From:<GandalfG8@aol.com>
>> To:<time-nuts@febo.com>
>> Sent: Tuesday, May 15, 2012 12:01 AM
>> Subject: Re: [time-nuts] wwvb weak on east coast especially when
>> thepre-amps
>> under wa...
>>
>>
>>> The other option of course is to pressurise the box with dry air to
>> ensure
>>> a positive pressure differential, such that the net flow is always
>> outwards
>>> at all points, but it's probably easier just to provide a drain hole:-)
>>>
>>> However, whilst a drain hole will prevent the build up of a lake inside
>> the
>>> enclosure it still doesn't prevent condensation forming on circuit
>> boards,
>>> and powered circuit boards and condensation don't really go well
>> together.
>>> As per earlier comments, it's quite difficult to keep any externally
>>> mounted enclosure totally moisture free, so it's much easier to accept
>> the
>>> inevitable and allow for it.
>>>
>>> In a past life I designed quite a few circuit boards that were required
>> to
>>> be fitted in externally mounted vented enclosures, so not a great deal
>> of
>>> pressurisation there then:-), and I usually specified that both sides
>>> should be sprayed with a plastic coating following final test.
>>>
>>> I can't remember now exactly what this stuff was called, but it was
>>> readily available in the UK from both RS and Farnell as an aerosol
>> plastic
>> spray
>>> that provided a good barrier but was a bit more flexible than the usual
>> MOD
>>> spec conformal coatings.
>>> It melted easily under a soldering iron, albeit with a foul pong:-), so
>>> reworking was no problem, and resisted moisture remarkably well.....
>>>
>>> problem solved:-)
>>>
>>> Nigel
>>> GM8PZR
>>>
>>>
>>>
>>>
>>>
>>> In a message dated 14/05/2012 23:10:30 GMT Daylight Time,
>>> arnold.tibus@gmx.de writes:
>>>
>>> The only solutions I think:
>>> Apply air pressure tight boxes having a breathing hole an the bottom,
>>> mount the
>>> box that no rain and water can penetrate from the top or sides. If the
>>> hole is big enough,
>>> eg. 2mm, no pressure difference is possible and no pumping effect will
>>> occur.
>>> (If the hole is too wide, small animals may penetrate).
>>> Or,
>>> when using a pressure tight box, it must be stiff and sealed to
>>> withstand under all
>>> temperature conditions more then 1 bar/ 100 kPa. Do not forget that all
>>> feed
>>> throughs must be of real hermetic type, normal coaxial connectors are
>>> not tight!
>>> Don't route cables directly in, because no cable braid or mesh is vapor
>>> tight.
>>> _______________________________________________
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>>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>>
>>
>>
>> ------------------------------
>>
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>>
>> End of time-nuts Digest, Vol 94, Issue 89
>> *****************************************
>>
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>
LM
Lee Mushel
Tue, May 15, 2012 4:30 AM
Be careful! You have now introduced a "label" into the discussion that
might trigger some vendor into thinking that you are looking for a UV Cured
coating. And those things can be something you don't want to mess with.
Back in the 70's when those coatings first appeared no one bothered to take
note that they are very chemically reactive---they have to be since UV light
is not a particularly agressive curing agent and to compensate for that UV
"cured" (not simply something that fluoresces)materials tend to be stuff
that you don't want to come in contact with. I can show you some places on
my left hand that break into open sores today, some 35 years later.
Today, no one doubts that they are carcinogens.
Lee Mushel
----- Original Message -----
From: "Michael Blazer" mblazer@satx.rr.com
To: time-nuts@febo.com
Sent: Monday, May 14, 2012 8:51 PM
Subject: Re: [time-nuts] Conformal Coating
The Humiseal product also has a UV indicator in it that glows blue under
a
black light so you can check coverage.
Be careful! You have now introduced a "label" into the discussion that
might trigger some vendor into thinking that you are looking for a UV Cured
coating. And those things can be something you don't want to mess with.
Back in the 70's when those coatings first appeared no one bothered to take
note that they are very chemically reactive---they have to be since UV light
is not a particularly agressive curing agent and to compensate for that UV
"cured" (not simply something that fluoresces)materials tend to be stuff
that you don't want to come in contact with. I can show you some places on
my left hand that break into open sores today, some 35 years later.
Today, no one doubts that they are carcinogens.
Lee Mushel
----- Original Message -----
From: "Michael Blazer" <mblazer@satx.rr.com>
To: <time-nuts@febo.com>
Sent: Monday, May 14, 2012 8:51 PM
Subject: Re: [time-nuts] Conformal Coating
>>
>> The Humiseal product also has a UV indicator in it that glows blue under
>> a
>> black light so you can check coverage.
>>
