Re: [time-nuts] Frequency counter recommendation
I don't believe anybody is speaking to perceived value as much as
historical market cost at various times over the years. I paid $200
for my 5370B last year and it's in superb condition and well inside
factory specs. There is no way I'd sell it though.
My guess is Bob C and most of us perceive the
value to be much greater, never mind the actual cost.
-Bob
On Mon, Dec 20, 2010 at 4:55 AM, Rex rexa@sonic.net wrote:
Why worry, Just get Bob C to sell you one of his several $200
5370A/B's for a reasonable $100 profit (plus shipping) and you'll
beat anything I've seen on eBay in the last year. Everyone should be
happy. Bob can can take the profit then (soon) easily get another to
replace it at his perceived value.
OK... you have piqued my interest. Who is Bob C (is it Bob Camp?) and how
can I contact him for one of those $200 HP 5370 counters? I'd much rather
spend $200-$300 on a unit that has a high probability of working than $700
on a "powers up, unable to test" unit from the 'Bay.
Hope he has at least one to sell.
As to whether I would rather have a dedicated purpose counter-timer strictly
for these measurements... I can live with a used/surplus unit that I can get
my hands on now (or in a short time) and wait until the designers in the
group can design and make a project that we can buy (whether it be kit or
preassembled) and put to good use.
I understand the issues of platform, connectivity, value, servicability,
parts availability, etc., but any project, whether it be a commercial
product or a dedicated, special purpose product, is going to be confronted
with the same issues. I've subscribed to the S.E.D. group when they have
tried to design and build test instruments (a capacitor ESR meter, for one)
that never got off the launchpad because of their inability to come to
consensus on a set of features. I had to conclude that too many cooks
spoiled the broth. Everyone that had input to the project was unwilling to
yield on anyone else's ideas. Hopefully, our project won't degrade into
another such fiasco.
I would jump at a chance to be a small part in this project, and would do
whatever I could (my limited engineering knowledge noted) to help it get
realized.
My $0.02 USD worth...
Thanks,
David
dgminala at mediacombb dot net
FWIW my recent experience buying a 5370B resulted in me:
Paying a price closer to $700.00 than $200.00 (but still under $700.00)
Receiving signficantly better representations from the seller than "powers up
unable to test."
There are still some good deals to be had on the bay.. I recently saw a lot of
two 5334's go for less than $100.00 After buying the 5370 and another 5328
with a high stab osilcator at a price that was to good to pass up I couldn't
justify buying two more counters.
----- Original Message ----
From: Dave M dgminala@mediacombb.net
To: time-nuts@febo.com
Sent: Mon, December 20, 2010 2:51:37 PM
Subject: Re: [time-nuts] Frequency counter recommendation
I don't believe anybody is speaking to perceived value as much as
historical market cost at various times over the years. I paid $200
for my 5370B last year and it's in superb condition and well inside
factory specs. There is no way I'd sell it though.
My guess is Bob C and most of us perceive the
value to be much greater, never mind the actual cost.
-Bob
On Mon, Dec 20, 2010 at 4:55 AM, Rex rexa@sonic.net wrote:
Why worry, Just get Bob C to sell you one of his several $200
5370A/B's for a reasonable $100 profit (plus shipping) and you'll
beat anything I've seen on eBay in the last year. Everyone should be
happy. Bob can can take the profit then (soon) easily get another to
replace it at his perceived value.
OK... you have piqued my interest. Who is Bob C (is it Bob Camp?) and how can I
contact him for one of those $200 HP 5370 counters? I'd much rather spend
$200-$300 on a unit that has a high probability of working than $700 on a
"powers up, unable to test" unit from the 'Bay.
Hope he has at least one to sell.
As to whether I would rather have a dedicated purpose counter-timer strictly for
these measurements... I can live with a used/surplus unit that I can get my
hands on now (or in a short time) and wait until the designers in the group can
design and make a project that we can buy (whether it be kit or preassembled)
and put to good use.
I understand the issues of platform, connectivity, value, servicability, parts
availability, etc., but any project, whether it be a commercial product or a
dedicated, special purpose product, is going to be confronted with the same
issues. I've subscribed to the S.E.D. group when they have tried to design and
build test instruments (a capacitor ESR meter, for one) that never got off the
launchpad because of their inability to come to consensus on a set of features.
I had to conclude that too many cooks spoiled the broth. Everyone that had input
to the project was unwilling to yield on anyone else's ideas. Hopefully, our
project won't degrade into another such fiasco.
I would jump at a chance to be a small part in this project, and would do
whatever I could (my limited engineering knowledge noted) to help it get
realized.
My $0.02 USD worth...
Thanks,
David
dgminala at mediacombb dot net
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.
On Mon, Dec 20, 2010 at 2:51 PM, Dave M dgminala@mediacombb.net wrote:
.. never got off the launchpad because of their inability to come to
consensus on a set of features. I had to conclude that too many cooks
spoiled the broth. Everyone that had input to the project was unwilling to
yield on anyone else's ideas. Hopefully, our project won't degrade into
another such fiasco.
THAT is the number one problem to solve. Technical issues are easy
I think the solution is to
(1) chop the project up into small enough parts, each on it's own PCB
so that each part is "easy" and has some wider user outside the
project.
(2) Find a mechanical standard so all the PCBs can be mounted in some
kind of chassis. I'm thinking now that maybe a 160-3U Eurocard would
be about right size. But the parts are expensive.
(3) Need some sort of design process that allows everyone to
contribute. And everyone can. Projects always are lacking technical
writers and quality control people
Of those a "process" and "mechanical standard", I think are the
hardest. We always give managers a hard time but that is what is
needed. The person who will make this happen will be a manager and
organizer maybe not a designer.
--
Chris Albertson
Redondo Beach, California
Well said Chris. Take a look at the initial spec in the OpenCounter Gogle
group and tell me what you think with respect to your item #1. I think the
core counter is going to be the really difficult part of the module list.
Item #2 is going to be a tough one methinks. I love Eurocard, but, as you
say, it is very expensive, if only for the connectors. In cases like this
I'm a fan of either repurposing commercially available connectors (PCI and
memory DIMMS are two I have used in the past) because they can be a)
purchased off the shelf, b) are manufactured in enough volume to make cheap,
and c) are common enough that the really cheap amongst us can get them off
of scrap boards someplace for little or nothing. The N2PK VNA is built to
fit into a particular HAmmond enclosure that I like but again, there are
many options. My feeling is that the enclosure should not dictate any
functional design decisions.
#3 - I've created a group and appointed myself benevolent dictator. We can
discuss things, propose designs or design criteria, call for a concensus,
accept, and draft volunteers to design that section to the defined spec. If
there are multiple competing designs, so much the better, as long as we all
agree on the interfaces. Sound like a process? Can you tell I've done this
once or twice? :)
Step one will be to agree on the overall functional spec. If we get enough
participants, I'd like to nail that down by mid January. The next step is to
agree on the interfaces between the modules. Same process, discuss, propose,
draft, get concensus, close and move on.
Then we get folks working on the individual modules.
On Mon, Dec 20, 2010 at 8:43 PM, Chris Albertson
albertson.chris@gmail.comwrote:
On Mon, Dec 20, 2010 at 2:51 PM, Dave M dgminala@mediacombb.net wrote:
.. never got off the launchpad because of their inability to come to
consensus on a set of features. I had to conclude that too many cooks
spoiled the broth. Everyone that had input to the project was unwilling
to
yield on anyone else's ideas. Hopefully, our project won't degrade into
another such fiasco.
THAT is the number one problem to solve. Technical issues are easy
I think the solution is to
(1) chop the project up into small enough parts, each on it's own PCB
so that each part is "easy" and has some wider user outside the
project.
(2) Find a mechanical standard so all the PCBs can be mounted in some
kind of chassis. I'm thinking now that maybe a 160-3U Eurocard would
be about right size. But the parts are expensive.
(3) Need some sort of design process that allows everyone to
contribute. And everyone can. Projects always are lacking technical
writers and quality control people
Of those a "process" and "mechanical standard", I think are the
hardest. We always give managers a hard time but that is what is
needed. The person who will make this happen will be a manager and
organizer maybe not a designer.
--
Chris Albertson
Redondo Beach, California
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.
Hi benevolent dictator. Please not the @#$%^& Eurocard. As you say, the
connectors and backplane cost more than the stuff on the cards (except
maybe the stuff from Hittite :-). Rather a stack of cards with .1 in.
spacing .025 pins? That way, we can put the stack in any housing we want.
If a suitable processor card (e.g. propeller or Arduino) is selected,
daughterboards can be stacked on that.
Just thinkin'. I've joined the google group.
Best,
Don
Bob Bownes
Well said Chris. Take a look at the initial spec in the OpenCounter Gogle
group and tell me what you think with respect to your item #1. I think the
core counter is going to be the really difficult part of the module list.
Item #2 is going to be a tough one methinks. I love Eurocard, but, as you
say, it is very expensive, if only for the connectors. In cases like this
I'm a fan of either repurposing commercially available connectors (PCI and
memory DIMMS are two I have used in the past) because they can be a)
purchased off the shelf, b) are manufactured in enough volume to make
cheap,
and c) are common enough that the really cheap amongst us can get them off
of scrap boards someplace for little or nothing. The N2PK VNA is built to
fit into a particular HAmmond enclosure that I like but again, there are
many options. My feeling is that the enclosure should not dictate any
functional design decisions.
#3 - I've created a group and appointed myself benevolent dictator. We can
discuss things, propose designs or design criteria, call for a concensus,
accept, and draft volunteers to design that section to the defined spec.
If
there are multiple competing designs, so much the better, as long as we
all
agree on the interfaces. Sound like a process? Can you tell I've done this
once or twice? :)
Step one will be to agree on the overall functional spec. If we get enough
participants, I'd like to nail that down by mid January. The next step is
to
agree on the interfaces between the modules. Same process, discuss,
propose,
draft, get concensus, close and move on.
Then we get folks working on the individual modules.
On Mon, Dec 20, 2010 at 8:43 PM, Chris Albertson
albertson.chris@gmail.comwrote:
On Mon, Dec 20, 2010 at 2:51 PM, Dave M dgminala@mediacombb.net wrote:
.. never got off the launchpad because of their inability to come to
consensus on a set of features. I had to conclude that too many cooks
spoiled the broth. Everyone that had input to the project was
unwilling
to
yield on anyone else's ideas. Hopefully, our project won't degrade
into
another such fiasco.
THAT is the number one problem to solve. Technical issues are easy
I think the solution is to
(1) chop the project up into small enough parts, each on it's own PCB
so that each part is "easy" and has some wider user outside the
project.
(2) Find a mechanical standard so all the PCBs can be mounted in some
kind of chassis. I'm thinking now that maybe a 160-3U Eurocard would
be about right size. But the parts are expensive.
(3) Need some sort of design process that allows everyone to
contribute. And everyone can. Projects always are lacking technical
writers and quality control people
Of those a "process" and "mechanical standard", I think are the
hardest. We always give managers a hard time but that is what is
needed. The person who will make this happen will be a manager and
organizer maybe not a designer.
--
Chris Albertson
Redondo Beach, California
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.
--
"Neither the voice of authority nor the weight of reason and argument are
as significant as experiment, for thence comes quiet to the mind."
R. Bacon
"If you don't know what it is, don't poke it."
Ghost in the Shell
Dr. Don Latham AJ7LL
Six Mile Systems LLP
17850 Six Mile Road
POB 134
Huson, MT, 59846
VOX 406-626-4304
www.lightningforensics.com
www.sixmilesystems.com
Lol. Ok. You're added to the group.
I've started a topic on form factor.
Bob
On Mon, Dec 20, 2010 at 10:45 PM, Don Latham djl@montana.com wrote:
Hi benevolent dictator. Please not the @#$%^& Eurocard. As you say, the
connectors and backplane cost more than the stuff on the cards (except
maybe the stuff from Hittite :-). Rather a stack of cards with .1 in.
spacing .025 pins? That way, we can put the stack in any housing we want.
If a suitable processor card (e.g. propeller or Arduino) is selected,
daughterboards can be stacked on that.
Just thinkin'. I've joined the google group.
Best,
Don
Bob Bownes
Well said Chris. Take a look at the initial spec in the OpenCounter Gogle
group and tell me what you think with respect to your item #1. I think
the
core counter is going to be the really difficult part of the module list.
Item #2 is going to be a tough one methinks. I love Eurocard, but, as you
say, it is very expensive, if only for the connectors. In cases like this
I'm a fan of either repurposing commercially available connectors (PCI
and
memory DIMMS are two I have used in the past) because they can be a)
purchased off the shelf, b) are manufactured in enough volume to make
cheap,
and c) are common enough that the really cheap amongst us can get them
off
of scrap boards someplace for little or nothing. The N2PK VNA is built to
fit into a particular HAmmond enclosure that I like but again, there are
many options. My feeling is that the enclosure should not dictate any
functional design decisions.
#3 - I've created a group and appointed myself benevolent dictator. We
can
discuss things, propose designs or design criteria, call for a concensus,
accept, and draft volunteers to design that section to the defined spec.
If
there are multiple competing designs, so much the better, as long as we
all
agree on the interfaces. Sound like a process? Can you tell I've done
this
once or twice? :)
Step one will be to agree on the overall functional spec. If we get
enough
participants, I'd like to nail that down by mid January. The next step is
to
agree on the interfaces between the modules. Same process, discuss,
propose,
draft, get concensus, close and move on.
Then we get folks working on the individual modules.
On Mon, Dec 20, 2010 at 8:43 PM, Chris Albertson
albertson.chris@gmail.comwrote:
On Mon, Dec 20, 2010 at 2:51 PM, Dave M dgminala@mediacombb.net
wrote:
.. never got off the launchpad because of their inability to come to
consensus on a set of features. I had to conclude that too many cooks
spoiled the broth. Everyone that had input to the project was
unwilling
to
yield on anyone else's ideas. Hopefully, our project won't degrade
into
another such fiasco.
THAT is the number one problem to solve. Technical issues are easy
I think the solution is to
(1) chop the project up into small enough parts, each on it's own PCB
so that each part is "easy" and has some wider user outside the
project.
(2) Find a mechanical standard so all the PCBs can be mounted in some
kind of chassis. I'm thinking now that maybe a 160-3U Eurocard would
be about right size. But the parts are expensive.
(3) Need some sort of design process that allows everyone to
contribute. And everyone can. Projects always are lacking technical
writers and quality control people
Of those a "process" and "mechanical standard", I think are the
hardest. We always give managers a hard time but that is what is
needed. The person who will make this happen will be a manager and
organizer maybe not a designer.
--
Chris Albertson
Redondo Beach, California
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.
--
"Neither the voice of authority nor the weight of reason and argument are
as significant as experiment, for thence comes quiet to the mind."
R. Bacon
"If you don't know what it is, don't poke it."
Ghost in the Shell
Dr. Don Latham AJ7LL
Six Mile Systems LLP
17850 Six Mile Road
POB 134
Huson, MT, 59846
VOX 406-626-4304
www.lightningforensics.com
www.sixmilesystems.com
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.
I looked. I think we should keep the design goals modest for a first
revision. Shoot for a spec that can be hand built on perf board. So
I'd relax those numbers by a factor of 1000. The top frequency is in
Mhz, not Ghz and the time resolution closer to ns than ps. It's good
to have a cheap option. Many people are happy with an FCC1 Try for
the next step after that with a goal of actually matching the state of
the art in steps.
Why no through holes? I don't see the point of banishing them. I to
agree with the rest. SMT that is hand solderable by a skilled tech
but now reflow ovens or solder past masks should be required . You
might place a limit on component size too like 0.5mm lead pitch or
whatever is reasonable.
Mechanical part is not easy. Need to re-purpose some mass produced
chassis. That keeps leading me back to computer hard drives. What if
you made the PCB the same size as a disk drive and then got some 1" x
1/4" aluminum L extrusion and screwed some of the aluminum around
three sides of the PCB. low-tech metal work but they might slide into
a disk drive enclosure that is made to house SATA drives. These
enclosures come in any size for one drive all the way up to 6 foot
racks.
If yu also place a aluminum L across the short side you have space for
conectors and switches
On Mon, Dec 20, 2010 at 6:20 PM, Bob Bownes bownes@gmail.com wrote:
Well said Chris. Take a look at the initial spec in the OpenCounter Gogle
group and tell me what you think with respect to your item #1. I think the
core counter is going to be the really difficult part of the module list.
Item #2 is going to be a tough one methinks. I love Eurocard, but, as you
say, it is very expensive, if only for the connectors. In cases like this
I'm a fan of either repurposing commercially available connectors (PCI and
memory DIMMS are two I have used in the past) because they can be a)
purchased off the shelf, b) are manufactured in enough volume to make cheap,
and c) are common enough that the really cheap amongst us can get them off
of scrap boards someplace for little or nothing. The N2PK VNA is built to
fit into a particular HAmmond enclosure that I like but again, there are
many options. My feeling is that the enclosure should not dictate any
functional design decisions.
#3 - I've created a group and appointed myself benevolent dictator. We can
discuss things, propose designs or design criteria, call for a concensus,
accept, and draft volunteers to design that section to the defined spec. If
there are multiple competing designs, so much the better, as long as we all
agree on the interfaces. Sound like a process? Can you tell I've done this
once or twice? :)
Step one will be to agree on the overall functional spec. If we get enough
participants, I'd like to nail that down by mid January. The next step is to
agree on the interfaces between the modules. Same process, discuss, propose,
draft, get concensus, close and move on.
Then we get folks working on the individual modules.
On Mon, Dec 20, 2010 at 8:43 PM, Chris Albertson
albertson.chris@gmail.comwrote:
On Mon, Dec 20, 2010 at 2:51 PM, Dave M dgminala@mediacombb.net wrote:
.. never got off the launchpad because of their inability to come to
consensus on a set of features. I had to conclude that too many cooks
spoiled the broth. Everyone that had input to the project was unwilling
to
yield on anyone else's ideas. Hopefully, our project won't degrade into
another such fiasco.
THAT is the number one problem to solve. Technical issues are easy
I think the solution is to
(1) chop the project up into small enough parts, each on it's own PCB
so that each part is "easy" and has some wider user outside the
project.
(2) Find a mechanical standard so all the PCBs can be mounted in some
kind of chassis. I'm thinking now that maybe a 160-3U Eurocard would
be about right size. But the parts are expensive.
(3) Need some sort of design process that allows everyone to
contribute. And everyone can. Projects always are lacking technical
writers and quality control people
Of those a "process" and "mechanical standard", I think are the
hardest. We always give managers a hard time but that is what is
needed. The person who will make this happen will be a manager and
organizer maybe not a designer.
--
Chris Albertson
Redondo Beach, California
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.
--
Chris Albertson
Redondo Beach, California
Comments inline.
On Mon, Dec 20, 2010 at 11:17 PM, Chris Albertson <albertson.chris@gmail.com
wrote:
I looked. I think we should keep the design goals modest for a first
revision. Shoot for a spec that can be hand built on perf board. So
I'd relax those numbers by a factor of 1000. The top frequency is in
Mhz, not Ghz and the time resolution closer to ns than ps. It's good
to have a cheap option. Many people are happy with an FCC1 Try for
the next step after that with a goal of actually matching the state of
the art in steps.
My initial thinking was to be better than a pictic ii, preferably on par
with, or better than a 5370. I'm not sure you can do that on perfboard. I
suppose if the speed is kept low it can be done that way.
Others have pointed out (offline) 20Ghz isn't reasonabe with a decent noise
figure or prescalers. What do people think a reasonable number is? What
about resolution? I'd like to get better than a ns, preferably a lot better.
Why no through holes? I don't see the point of banishing them. I to
agree with the rest. SMT that is hand solderable by a skilled tech
but now reflow ovens or solder past masks should be required . You
might place a limit on component size too like 0.5mm lead pitch or
whatever is reasonable.
I've been prototyping a lot of late and restricting the number of through
holes makes the job much much easier and quicker. No other real reason.
I didn't place a limit on the lead pitch because a) I felt that limited the
component selection and b) pretty much even the finest pitch can be hand
assembled with care, solder wick, and 20x magnification. But if folks are
very against it, it can go in the 'desired qualities' list. My only fear is
the limit it might put on critical parts like a FPGA.
Mechanical assy is going to be a killer. Let's start with overall form
factor.
Rack mount or bench format?
If rack mount, 1U or more?
Commercial project enclosure (ala the VNA Hammond box) or do we take
an existing form factor like a disk drive as you suggest.
Heck, if we go with a disk drive size, it could be built/slid into anyone's
lab PC case and use ribbon cable as a back plane... 1/2 :)
I like 1U because it matches up with the rest of the test equipment on the
bench and it gives it a professional feel. And there are many many surplus
1U cases out there with decent +/-12vdc,+5vdc (even some with 3.3vdc) power
supplies.
Bob
On Mon, Dec 20, 2010 at 6:20 PM, Bob Bownes bownes@gmail.com wrote:
Well said Chris. Take a look at the initial spec in the OpenCounter Gogle
group and tell me what you think with respect to your item #1. I think
the
core counter is going to be the really difficult part of the module list.
Item #2 is going to be a tough one methinks. I love Eurocard, but, as you
say, it is very expensive, if only for the connectors. In cases like this
I'm a fan of either repurposing commercially available connectors (PCI
and
memory DIMMS are two I have used in the past) because they can be a)
purchased off the shelf, b) are manufactured in enough volume to make
cheap,
and c) are common enough that the really cheap amongst us can get them
off
of scrap boards someplace for little or nothing. The N2PK VNA is built to
fit into a particular HAmmond enclosure that I like but again, there are
many options. My feeling is that the enclosure should not dictate any
functional design decisions.
#3 - I've created a group and appointed myself benevolent dictator. We
can
discuss things, propose designs or design criteria, call for a concensus,
accept, and draft volunteers to design that section to the defined spec.
If
there are multiple competing designs, so much the better, as long as we
all
agree on the interfaces. Sound like a process? Can you tell I've done
this
once or twice? :)
Step one will be to agree on the overall functional spec. If we get
enough
participants, I'd like to nail that down by mid January. The next step is
to
agree on the interfaces between the modules. Same process, discuss,
propose,
draft, get concensus, close and move on.
Then we get folks working on the individual modules.
On Mon, Dec 20, 2010 at 8:43 PM, Chris Albertson
albertson.chris@gmail.comwrote:
On Mon, Dec 20, 2010 at 2:51 PM, Dave M dgminala@mediacombb.net
wrote:
.. never got off the launchpad because of their inability to come to
consensus on a set of features. I had to conclude that too many cooks
spoiled the broth. Everyone that had input to the project was
unwilling
to
yield on anyone else's ideas. Hopefully, our project won't degrade
into
another such fiasco.
THAT is the number one problem to solve. Technical issues are easy
I think the solution is to
(1) chop the project up into small enough parts, each on it's own PCB
so that each part is "easy" and has some wider user outside the
project.
(2) Find a mechanical standard so all the PCBs can be mounted in some
kind of chassis. I'm thinking now that maybe a 160-3U Eurocard would
be about right size. But the parts are expensive.
(3) Need some sort of design process that allows everyone to
contribute. And everyone can. Projects always are lacking technical
writers and quality control people
Of those a "process" and "mechanical standard", I think are the
hardest. We always give managers a hard time but that is what is
needed. The person who will make this happen will be a manager and
organizer maybe not a designer.
--
Chris Albertson
Redondo Beach, California
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
and follow the instructions there.
--
Chris Albertson
Redondo Beach, California
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.
Bob Bownes wrote:
Comments inline.
On Mon, Dec 20, 2010 at 11:17 PM, Chris Albertson<albertson.chris@gmail.com
wrote:
I looked. I think we should keep the design goals modest for a first
revision. Shoot for a spec that can be hand built on perf board. So
I'd relax those numbers by a factor of 1000. The top frequency is in
Mhz, not Ghz and the time resolution closer to ns than ps. It's good
to have a cheap option. Many people are happy with an FCC1 Try for
the next step after that with a goal of actually matching the state of
the art in steps.
My initial thinking was to be better than a pictic ii, preferably on par
with, or better than a 5370. I'm not sure you can do that on perfboard. I
suppose if the speed is kept low it can be done that way.
Around 25ps jitter is the likely lower limit with such construction
techniques.
Others have pointed out (offline) 20Ghz isn't reasonabe with a decent noise
figure or prescalers. What do people think a reasonable number is? What
about resolution? I'd like to get better than a ns, preferably a lot better.
1ps resolution is trivial just use a sufficiently high resolution ADC
(16bit) with a short TAC interpolator range (10ns?)
Achieving a commensurate jitter is somewhat trickier.
Around 3ps or so rms short term jitter should be easy enough, the
Wavercrest 2075 does this without using anything particularly esoteric.
10ps jitter should be very easy.
The latest Agilent time interval counters counters achieve around 9ps or so.
1ps rms jitter shouldn't be beyond reach (at least with the ringing tank
method).
However a good layout together with at least a 4 layer board will likely
be necessary.
Adequate grounding and shielding will also be necessary.
Why no through holes? I don't see the point of banishing them. I to
agree with the rest. SMT that is hand solderable by a skilled tech
but now reflow ovens or solder past masks should be required . You
might place a limit on component size too like 0.5mm lead pitch or
whatever is reasonable.
I've been prototyping a lot of late and restricting the number of through
holes makes the job much much easier and quicker. No other real reason.
Precluding the use of RF dams (these use arrays of plated through
holes) is probably counter productive.
I didn't place a limit on the lead pitch because a) I felt that limited the
component selection and b) pretty much even the finest pitch can be hand
assembled with care, solder wick, and 20x magnification. But if folks are
very against it, it can go in the 'desired qualities' list. My only fear is
the limit it might put on critical parts like a FPGA.
Mechanical assy is going to be a killer. Let's start with overall form
factor.
Rack mount or bench format?
If rack mount, 1U or more?
Commercial project enclosure (ala the VNA Hammond box) or do we take
an existing form factor like a disk drive as you suggest.
Heck, if we go with a disk drive size, it could be built/slid into anyone's
lab PC case and use ribbon cable as a back plane... 1/2 :)
Inadequate shielding?
I like 1U because it matches up with the rest of the test equipment on the
bench and it gives it a professional feel. And there are many many surplus
1U cases out there with decent +/-12vdc,+5vdc (even some with 3.3vdc) power
supplies.
Linear supplies or perhaps extremely low noise/well filtered switchmode
supplies will likely be necessary.
Bob
Bruce
On Mon, Dec 20, 2010 at 6:20 PM, Bob Bownesbownes@gmail.com wrote:
Well said Chris. Take a look at the initial spec in the OpenCounter Gogle
group and tell me what you think with respect to your item #1. I think
the
core counter is going to be the really difficult part of the module list.
Item #2 is going to be a tough one methinks. I love Eurocard, but, as you
say, it is very expensive, if only for the connectors. In cases like this
I'm a fan of either repurposing commercially available connectors (PCI
and
memory DIMMS are two I have used in the past) because they can be a)
purchased off the shelf, b) are manufactured in enough volume to make
cheap,
and c) are common enough that the really cheap amongst us can get them
off
of scrap boards someplace for little or nothing. The N2PK VNA is built to
fit into a particular HAmmond enclosure that I like but again, there are
many options. My feeling is that the enclosure should not dictate any
functional design decisions.
#3 - I've created a group and appointed myself benevolent dictator. We
can
discuss things, propose designs or design criteria, call for a concensus,
accept, and draft volunteers to design that section to the defined spec.
If
there are multiple competing designs, so much the better, as long as we
all
agree on the interfaces. Sound like a process? Can you tell I've done
this
once or twice? :)
Step one will be to agree on the overall functional spec. If we get
enough
participants, I'd like to nail that down by mid January. The next step is
to
agree on the interfaces between the modules. Same process, discuss,
propose,
draft, get concensus, close and move on.
Then we get folks working on the individual modules.
On Mon, Dec 20, 2010 at 8:43 PM, Chris Albertson
albertson.chris@gmail.comwrote:
On Mon, Dec 20, 2010 at 2:51 PM, Dave Mdgminala@mediacombb.net
wrote:
.. never got off the launchpad because of their inability to come to
consensus on a set of features. I had to conclude that too many cooks
spoiled the broth. Everyone that had input to the project was
unwilling
to
yield on anyone else's ideas. Hopefully, our project won't degrade
into
another such fiasco.
THAT is the number one problem to solve. Technical issues are easy
I think the solution is to
(1) chop the project up into small enough parts, each on it's own PCB
so that each part is "easy" and has some wider user outside the
project.
(2) Find a mechanical standard so all the PCBs can be mounted in some
kind of chassis. I'm thinking now that maybe a 160-3U Eurocard would
be about right size. But the parts are expensive.
(3) Need some sort of design process that allows everyone to
contribute. And everyone can. Projects always are lacking technical
writers and quality control people
Of those a "process" and "mechanical standard", I think are the
hardest. We always give managers a hard time but that is what is
needed. The person who will make this happen will be a manager and
organizer maybe not a designer.
--
Chris Albertson
Redondo Beach, California
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--
Chris Albertson
Redondo Beach, California
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