oscillator choice question
I'd like to build a GPS disciplined frequency standard.
I am slowly gathering up pieces.
I have a Trimble Resolution T GPS card that appears to work,
and an antenna for it.
I'm thinking now of the oscillator part.
I have two Racal 1992 counters with the stable oscillator option
(probably 04E since these are former military units). I also have an
old Schomandl ND-100M Frequenzdecade signal source with an (I assume)
ovenized oscillator w/unknown properties.
I'm wondering if I could use an oscillator from one of these
gizmos instead of shelling out real money on ebay? Speaking of
which, it seems like half the people in China are selling oscillators.
I assume some of them are good for this application and some not
so good? The usual suspects from HP and Agilent are there, and
they seem to command a pretty good (high) price. Which is why
I'm eyeing the Schomandl.
Chris
w0ep
Chris,
Careful. What you are contemplating can be very addicting.
I am not familiar with the units you mentioned but I have used the HP 10811.
They can be had for not much money on occasion but seem to be around $100
now days. One such example is 350335841291 on e..y.
I have also used an HP 105B which is a stand alone system that includes
power supply, battery back up, and puts out 5 MHz, 1 MHz and 100 KHz. Both
used Brooks Shera's controller card and seemed to work ok. It offers rather
easy integration with the GPS controller card as well as the ability to
remain on and fairly stable once disciplined.
I suspect this would be good as well, 180399463609, on e..y.
The Trimble Thunderbolt needs +5 VDC, +12 VDC and -12 VDC but is a self
contained GPSDO putting out 1 PPS and 10 MHz. Not much construction
required with this but needs a computer to monitor function.
How do you plan to discipline the oscillator?
Joe
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of chris@yipyap.com
Sent: Saturday, May 01, 2010 2:28 PM
To: time-nuts@febo.com
Subject: [time-nuts] oscillator choice question
I'd like to build a GPS disciplined frequency standard.
I am slowly gathering up pieces.
I have a Trimble Resolution T GPS card that appears to work, and an antenna
for it.
I'm thinking now of the oscillator part.
I have two Racal 1992 counters with the stable oscillator option
(probably 04E since these are former military units). I also have an
old Schomandl ND-100M Frequenzdecade signal source with an (I assume)
ovenized oscillator w/unknown properties.
I'm wondering if I could use an oscillator from one of these gizmos instead
of shelling out real money on ebay? Speaking of which, it seems like half
the people in China are selling oscillators. I assume some of them are good
for this application and some not so good? The usual suspects from HP and
Agilent are there, and they seem to command a pretty good (high) price.
Which is why I'm eyeing the Schomandl.
Chris
w0ep
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Hi Chris,The Racal high stability units usually use the 9420 series OCXO's. These are good oscillators but do not have electronic tuning as standard. 'they are also normally 5MHz. What is the best oscillaor depends on your requirements. The two main parameters are phase noise and hold-over performance. Hold over is how much the oscillator will drift if the GPS loses signal.
Robert G8RPI.
--- On Sat, 1/5/10, chris@yipyap.com chris@yipyap.com wrote:
From: chris@yipyap.com chris@yipyap.com
Subject: [time-nuts] oscillator choice question
To: time-nuts@febo.com
Date: Saturday, 1 May, 2010, 20:28
I'd like to build a GPS disciplined frequency standard.
I am slowly gathering up pieces.
I have a Trimble Resolution T GPS card that appears to work,
and an antenna for it.
I'm thinking now of the oscillator part.
I have two Racal 1992 counters with the stable oscillator option (probably 04E since these are former military units). I also have an old Schomandl ND-100M Frequenzdecade signal source with an (I assume) ovenized oscillator w/unknown properties.
I'm wondering if I could use an oscillator from one of these
gizmos instead of shelling out real money on ebay? Speaking of
which, it seems like half the people in China are selling oscillators.
I assume some of them are good for this application and some not
so good? The usual suspects from HP and Agilent are there, and
they seem to command a pretty good (high) price. Which is why
I'm eyeing the Schomandl.
Chris
w0ep
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and follow the instructions there.
If there is no electronic tuning available one can use a DDS based
synthesiser to produce a corrected output frequency.
However close in spurs will be problematic unless one use a couple of
simple mix and divide stages or resorts to a Diophantine synthesiser
using phase noise truncation spur free output frequencies from the DDS
chip(s).
Alternatively if one implements the DDS in an FPGA its possible to
virtually eliminate such spurs using a modified algorithm.
However this requires an external DAC to produce the required output.
Bruce
Robert Atkinson wrote:
Hi Chris,The Racal high stability units usually use the 9420 series OCXO's. These are good oscillators but do not have electronic tuning as standard. 'they are also normally 5MHz. What is the best oscillaor depends on your requirements. The two main parameters are phase noise and hold-over performance. Hold over is how much the oscillator will drift if the GPS loses signal.
Robert G8RPI.
--- On Sat, 1/5/10, chris@yipyap.comchris@yipyap.com wrote:
From: chris@yipyap.comchris@yipyap.com
Subject: [time-nuts] oscillator choice question
To: time-nuts@febo.com
Date: Saturday, 1 May, 2010, 20:28
I'd like to build a GPS disciplined frequency standard.
I am slowly gathering up pieces.
I have a Trimble Resolution T GPS card that appears to work,
and an antenna for it.
I'm thinking now of the oscillator part.
I have two Racal 1992 counters with the stable oscillator option (probably 04E since these are former military units). I also have an old Schomandl ND-100M Frequenzdecade signal source with an (I assume) ovenized oscillator w/unknown properties.
I'm wondering if I could use an oscillator from one of these
gizmos instead of shelling out real money on ebay? Speaking of
which, it seems like half the people in China are selling oscillators.
I assume some of them are good for this application and some not
so good? The usual suspects from HP and Agilent are there, and
they seem to command a pretty good (high) price. Which is why
I'm eyeing the Schomandl.
Chris
w0ep
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Hi
A lot depends on what sort of result you are looking for.
If a simple calibration of the standard in your counter to +/- 1 ppb is your goal, then a reasonable oscilloscope and some patience will get the job done with what you already have.
If continuos lock to GPS at a 10X or 100X tighter level is the goal, it's tough to beat a Thunderbolt at around $100.
Most modern gear is looking for a 10 MHz standard input. It's easier to start with 10 and divide for the item that wants 0.1, 1, or 5 MHz than to multiply up from something lower. I would limit my shopping list to OCXO's that already put out 10 MHz and have a voltage control input. There are usually a bunch of them being auctioned in the $50 range. If your accuracy requirement's aren't to tight, you can indeed use a TCXO. If you wait long enough, you probably can score a 10 MHz rubidium for $70 - they make fine GPSDO's ....
Regardless of the oscillator used, you will still need some sort of electronics in-between the Res-T and the oscillator. The complexity is up to you. A lot of what you are doing is the same weather you are running a TCXO or a Rb.
It all depends on you needs and your budget.
Bob
On May 1, 2010, at 3:28 PM, chris@yipyap.com wrote:
I'd like to build a GPS disciplined frequency standard.
I am slowly gathering up pieces.
I have a Trimble Resolution T GPS card that appears to work,
and an antenna for it.
I'm thinking now of the oscillator part.
I have two Racal 1992 counters with the stable oscillator option (probably 04E since these are former military units). I also have an old Schomandl ND-100M Frequenzdecade signal source with an (I assume) ovenized oscillator w/unknown properties.
I'm wondering if I could use an oscillator from one of these
gizmos instead of shelling out real money on ebay? Speaking of
which, it seems like half the people in China are selling oscillators.
I assume some of them are good for this application and some not
so good? The usual suspects from HP and Agilent are there, and
they seem to command a pretty good (high) price. Which is why
I'm eyeing the Schomandl.
Chris
w0ep
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and follow the instructions there.
Don't do it, it may drag you deep into nut territory...
All i wanted was a clock based on a cheap LPro rubidium.
Next thing i knew were strange things piling up on my desk.
Now theres a custom power supply, 7 AVRs on a couple of boards,
an FPGA running a 1GHz counter, a lump of metal and some rather
nice blinkenlights.
Does anybody else have an atomic clock with ir remote control,
a gregorian calendar (1582-29999), full leap year support,
all official holydays incl. easter date calculation, alarm mode
with snooze and 4 bit snooze period counter that is shifted out
in a kind of frequency modulation, a temp controlled fan for the
LPro, external c-field adjustment via d/a converter, pc interface
and software for logging, time setting and main avr memory dumps,
it even knows (quite acurately) how many ns its off the gps 1pps.
Did i mention the alarm can be set to only ring on days i have to work?
And it ain't even finished yet.
You see? Don't do it, don't even think about starting.
Go buy a trimble thunderbolt, it will save you LOTS of time!
http://www.dulli.org/pics/20100502%20-%20Clock.jpg
-------- Original-Nachricht --------
Datum: Sat, 01 May 2010 14:28:04 -0500
Von: "chris@yipyap.com" chris@yipyap.com
An: time-nuts@febo.com
Betreff: [time-nuts] oscillator choice question
I'd like to build a GPS disciplined frequency standard.
I am slowly gathering up pieces.
I have a Trimble Resolution T GPS card that appears to work,
and an antenna for it.
I'm thinking now of the oscillator part.
I have two Racal 1992 counters with the stable oscillator option
(probably 04E since these are former military units). I also have an
old Schomandl ND-100M Frequenzdecade signal source with an (I assume)
ovenized oscillator w/unknown properties.
I'm wondering if I could use an oscillator from one of these
gizmos instead of shelling out real money on ebay? Speaking of
which, it seems like half the people in China are selling oscillators.
I assume some of them are good for this application and some not
so good? The usual suspects from HP and Agilent are there, and
they seem to command a pretty good (high) price. Which is why
I'm eyeing the Schomandl.
Chris
w0ep
time-nuts mailing list -- time-nuts@febo.com
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--
"Feel free" - 10 GB Mailbox, 100 FreeSMS/Monat ...
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That is a really cool picture.
Can I be like you when I grow up?
I've figured out which of these silvered modules
in this Schomandl sig gen is the oscillator (the one that
got warm). I have to figure out if it is voltage adjustable
in some way.
Does anyone use mechanical adjustment with a servo,
gear train and microcontroller?
I did hear all of those good advisers telling me to
buy the Thunderbolt. But I already have these pieces
so...
--
Chris
w0ep
Niels Lueddecke wrote:
You see? Don't do it, don't even think about starting.
Go buy a trimble thunderbolt, it will save you LOTS of time!
Does anyone use mechanical adjustment with a servo,
gear train and microcontroller?
Might be useful as a tool to calibrate standards without electronic fine adjustment but would think it would ware out the capacitor if used to make continuous adjustments. Wonder if they make adjustment tools with a gear train ?
Stanley
Hi
A coupe of issues with mechanical servo tuning:
-
It wears out the tuning capacitor pretty fast. They are designed for a limited number of adjustments. They loosen up with a lot of tuning and this degrades their stability.
-
It would be much easier to tear apart the mechanical tune OCXO and put in a tuning diode than to rig a thermally isolated high resolution servo stepper
-
Mechanical tune arrangements normally have backlash. That's not an issue as long as the servo only goes one way. It becomes a real pain to correct for each time you reverse direction.
-
Making a mechanical setup with a minimum step below 1 ppt is going to be more than just a simple stepper. A gear chain based system will be pretty exciting to work up. Backlash in the gears will add to what ever you have in the tune it's self.
-
The tuning on the OCXO may not be monotonic. That's especially true if you do indeed run the trimmer at a higher resolution than a normal human could adjust it. Tuning reversals tend to drive servo loops a bit crazy.
None of that says that it can't be done. All it says is that it will be hard to do well.
What kind of accuracy are you trying to obtain?
Bob
On May 2, 2010, at 3:18 PM, chris@yipyap.com wrote:
That is a really cool picture.
Can I be like you when I grow up?
I've figured out which of these silvered modules
in this Schomandl sig gen is the oscillator (the one that
got warm). I have to figure out if it is voltage adjustable
in some way.
Does anyone use mechanical adjustment with a servo,
gear train and microcontroller?
I did hear all of those good advisers telling me to
buy the Thunderbolt. But I already have these pieces
so...
--
Chris
w0ep
Niels Lueddecke wrote:
You see? Don't do it, don't even think about starting.
Go buy a trimble thunderbolt, it will save you LOTS of time!
http://www.dulli.org/pics/20100502%20-%20Clock.jpg
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 Camp wrote:
Hi
A coupe of issues with mechanical servo tuning:
-
It wears out the tuning capacitor pretty fast. They are designed for a limited number of adjustments. They loosen up with a lot of tuning and this degrades their stability.
-
It would be much easier to tear apart the mechanical tune OCXO and put in a tuning diode than to rig a thermally isolated high resolution servo stepper
-
Mechanical tune arrangements normally have backlash. That's not an issue as long as the servo only goes one way. It becomes a real pain to correct for each time you reverse direction.
One solution to which is to add (in addition to the servo motor) a
torque motor to preload the gear train so that the same flank of each
gear tooth is in contact for both directions of rotation. Zero backlash
drive reduction systems are also available at some considerable cost.
-
Making a mechanical setup with a minimum step below 1 ppt is going to be more than just a simple stepper. A gear chain based system will be pretty exciting to work up. Backlash in the gears will add to what ever you have in the tune it's self.
-
The tuning on the OCXO may not be monotonic. That's especially true if you do indeed run the trimmer at a higher resolution than a normal human could adjust it. Tuning reversals tend to drive servo loops a bit crazy.
None of that says that it can't be done. All it says is that it will be hard to do well.
What kind of accuracy are you trying to obtain?
Bob
Bruce
On May 2, 2010, at 3:18 PM, chris@yipyap.com wrote:
That is a really cool picture.
Can I be like you when I grow up?
I've figured out which of these silvered modules
in this Schomandl sig gen is the oscillator (the one that
got warm). I have to figure out if it is voltage adjustable
in some way.
Does anyone use mechanical adjustment with a servo,
gear train and microcontroller?
I did hear all of those good advisers telling me to
buy the Thunderbolt. But I already have these pieces
so...
--
Chris
w0ep
Niels Lueddecke wrote:
You see? Don't do it, don't even think about starting.
Go buy a trimble thunderbolt, it will save you LOTS of time!
http://www.dulli.org/pics/20100502%20-%20Clock.jpg
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.
Hi
An R-390A (or an not an A) has a lot of examples of how to do anti-backlash gear trains. Pretty tough to do on a one up fab from scratch in the basement basis though.
Lots easier to kludge in a low capacitance tuning diode .....
Bob
On May 2, 2010, at 3:54 PM, Bruce Griffiths wrote:
Bob Camp wrote:
Hi
A coupe of issues with mechanical servo tuning:
-
It wears out the tuning capacitor pretty fast. They are designed for a limited number of adjustments. They loosen up with a lot of tuning and this degrades their stability.
-
It would be much easier to tear apart the mechanical tune OCXO and put in a tuning diode than to rig a thermally isolated high resolution servo stepper
-
Mechanical tune arrangements normally have backlash. That's not an issue as long as the servo only goes one way. It becomes a real pain to correct for each time you reverse direction.
One solution to which is to add (in addition to the servo motor) a torque motor to preload the gear train so that the same flank of each gear tooth is in contact for both directions of rotation. Zero backlash drive reduction systems are also available at some considerable cost.
-
Making a mechanical setup with a minimum step below 1 ppt is going to be more than just a simple stepper. A gear chain based system will be pretty exciting to work up. Backlash in the gears will add to what ever you have in the tune it's self.
-
The tuning on the OCXO may not be monotonic. That's especially true if you do indeed run the trimmer at a higher resolution than a normal human could adjust it. Tuning reversals tend to drive servo loops a bit crazy.
None of that says that it can't be done. All it says is that it will be hard to do well.
What kind of accuracy are you trying to obtain?
Bob
Bruce
On May 2, 2010, at 3:18 PM, chris@yipyap.com wrote:
That is a really cool picture.
Can I be like you when I grow up?
I've figured out which of these silvered modules
in this Schomandl sig gen is the oscillator (the one that
got warm). I have to figure out if it is voltage adjustable
in some way.
Does anyone use mechanical adjustment with a servo,
gear train and microcontroller?
I did hear all of those good advisers telling me to
buy the Thunderbolt. But I already have these pieces
so...
--
Chris
w0ep
Niels Lueddecke wrote:
You see? Don't do it, don't even think about starting.
Go buy a trimble thunderbolt, it will save you LOTS of time!
http://www.dulli.org/pics/20100502%20-%20Clock.jpg
time-nuts mailing list -- time-nuts@febo.com
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Bob asks a reasonable question:
What kind of accuracy are you trying to obtain?
Bob
I would like to end up with something that is usable
on a home electronics workbench. Something like a
Z3801. Something I can use if I ever try to do some
goofing around with microwave radio operation.
I'm not serious enough to want to spend hundreds
on a working unit. On the other hand, lashing up
something that works would count toward my
hobby/education so then it is ok to spend a little
bit of money.
Hi
Microwave radio suggests low spurs and often low phase noise. That's on top of the stability requirements.
In terms of stability a good Z3801 will run rings around a garden variety Thunderbolt. Both are significantly better on phase noise than a "garden variety" OCXO. You will need a very good OCXO to get to the performance level of either one. The 10811 is probably the easiest thing to both identify and find. You see them selling anywhere from $100 to $200 depending on just how patient you are.
Bob
On May 2, 2010, at 4:13 PM, chris@yipyap.com wrote:
Bob asks a reasonable question:
What kind of accuracy are you trying to obtain?
Bob
I would like to end up with something that is usable
on a home electronics workbench. Something like a
Z3801. Something I can use if I ever try to do some
goofing around with microwave radio operation.
I'm not serious enough to want to spend hundreds
on a working unit. On the other hand, lashing up
something that works would count toward my
hobby/education so then it is ok to spend a little
bit of money.
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and follow the instructions there.
Or you could rotate the whole OCXO on flexible leads through 180* and
let gravity tune your frequency.
The range might be small, but an occasional tweak on the frequency
control might be acceptible.
cheers, Neville Michie
On 03/05/2010, at 6:00 AM, Bob Camp wrote:
Hi
An R-390A (or an not an A) has a lot of examples of how to do anti-
backlash gear trains. Pretty tough to do on a one up fab from
scratch in the basement basis though.
Lots easier to kludge in a low capacitance tuning diode .....
Bob
On May 2, 2010, at 3:54 PM, Bruce Griffiths wrote:
Bob Camp wrote:
Hi
A coupe of issues with mechanical servo tuning:
-
It wears out the tuning capacitor pretty fast. They are
designed for a limited number of adjustments. They loosen up with
a lot of tuning and this degrades their stability. -
It would be much easier to tear apart the mechanical tune OCXO
and put in a tuning diode than to rig a thermally isolated high
resolution servo stepper -
Mechanical tune arrangements normally have backlash. That's
not an issue as long as the servo only goes one way. It becomes a
real pain to correct for each time you reverse direction.
One solution to which is to add (in addition to the servo motor) a
torque motor to preload the gear train so that the same flank of
each gear tooth is in contact for both directions of rotation.
Zero backlash drive reduction systems are also available at some
considerable cost.
-
Making a mechanical setup with a minimum step below 1 ppt is
going to be more than just a simple stepper. A gear chain based
system will be pretty exciting to work up. Backlash in the gears
will add to what ever you have in the tune it's self. -
The tuning on the OCXO may not be monotonic. That's especially
true if you do indeed run the trimmer at a higher resolution than
a normal human could adjust it. Tuning reversals tend to drive
servo loops a bit crazy.
None of that says that it can't be done. All it says is that it
will be hard to do well.
What kind of accuracy are you trying to obtain?
Bob
Bruce
On May 2, 2010, at 3:18 PM, chris@yipyap.com wrote:
That is a really cool picture.
Can I be like you when I grow up?
I've figured out which of these silvered modules
in this Schomandl sig gen is the oscillator (the one that
got warm). I have to figure out if it is voltage adjustable
in some way.
Does anyone use mechanical adjustment with a servo,
gear train and microcontroller?
I did hear all of those good advisers telling me to
buy the Thunderbolt. But I already have these pieces
so...
--
Chris
w0ep
Niels Lueddecke wrote:
You see? Don't do it, don't even think about starting.
Go buy a trimble thunderbolt, it will save you LOTS of time!
http://www.dulli.org/pics/20100502%20-%20Clock.jpg
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.
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time-nuts
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Hi
Certainly a lot less backlash than the mechanical trimmer. There would still be some minor issues due to the internal heat flow changing as you rotated the part. No obvious issues with wear out. Probably could use some kind of belt to drive a large wheel to get around the gear train. Six foot diameter wheel driven by a 1/4" shaft should do pretty well.
Bob
On May 2, 2010, at 9:24 PM, Neville Michie wrote:
Or you could rotate the whole OCXO on flexible leads through 180* and let gravity tune your frequency.
The range might be small, but an occasional tweak on the frequency control might be acceptible.
cheers, Neville Michie
On 03/05/2010, at 6:00 AM, Bob Camp wrote:
Hi
An R-390A (or an not an A) has a lot of examples of how to do anti-backlash gear trains. Pretty tough to do on a one up fab from scratch in the basement basis though.
Lots easier to kludge in a low capacitance tuning diode .....
Bob
On May 2, 2010, at 3:54 PM, Bruce Griffiths wrote:
Bob Camp wrote:
Hi
A coupe of issues with mechanical servo tuning:
-
It wears out the tuning capacitor pretty fast. They are designed for a limited number of adjustments. They loosen up with a lot of tuning and this degrades their stability.
-
It would be much easier to tear apart the mechanical tune OCXO and put in a tuning diode than to rig a thermally isolated high resolution servo stepper
-
Mechanical tune arrangements normally have backlash. That's not an issue as long as the servo only goes one way. It becomes a real pain to correct for each time you reverse direction.
One solution to which is to add (in addition to the servo motor) a torque motor to preload the gear train so that the same flank of each gear tooth is in contact for both directions of rotation. Zero backlash drive reduction systems are also available at some considerable cost.
-
Making a mechanical setup with a minimum step below 1 ppt is going to be more than just a simple stepper. A gear chain based system will be pretty exciting to work up. Backlash in the gears will add to what ever you have in the tune it's self.
-
The tuning on the OCXO may not be monotonic. That's especially true if you do indeed run the trimmer at a higher resolution than a normal human could adjust it. Tuning reversals tend to drive servo loops a bit crazy.
None of that says that it can't be done. All it says is that it will be hard to do well.
What kind of accuracy are you trying to obtain?
Bob
Bruce
On May 2, 2010, at 3:18 PM, chris@yipyap.com wrote:
That is a really cool picture.
Can I be like you when I grow up?
I've figured out which of these silvered modules
in this Schomandl sig gen is the oscillator (the one that
got warm). I have to figure out if it is voltage adjustable
in some way.
Does anyone use mechanical adjustment with a servo,
gear train and microcontroller?
I did hear all of those good advisers telling me to
buy the Thunderbolt. But I already have these pieces
so...
--
Chris
w0ep
Niels Lueddecke wrote:
You see? Don't do it, don't even think about starting.
Go buy a trimble thunderbolt, it will save you LOTS of time!
http://www.dulli.org/pics/20100502%20-%20Clock.jpg
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.
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To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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just for show-and-tell:
I've been disassembling the Schmomandl ND100M oscillator
block to see if I could use it. I figured, it's the bird
in hand, and once was a high quality piece of equipment
so maybe...
The physical construction is great. Lots of fine pitch
slot head machine screws. Lots of silver plating.
The oscillator unit is long and narrow. It goes
in the 19" rack mount unit in the "depth" direction,
front to back in the upper left hand corner of what
turns out to be a more or less solid block of plated
boxes that make up the whole frequency generator.
Decade controls on the front are switches only. Each
is wired to a decade unit/card and the decade units are
fed signal all in series. Computerish connectors
at the back reproduce the decade switches in some
manner, so the thing can be remotely controlled
for frequency output.
I have four rough pictures.
www.yipyap.com/radio_stuff/ND100M/One.pdf is right (rear)
end of the component side.
www.yipyap.com/radio_stuff/ND100M/Four.pdf is the left (front)
end of the component side.
www.yipyap.com/radio_stuff/ND100M/Two.pdf is a blurry closeup
of the center from the trace side.
www.yipyap.com/radio_stuff/ND100M/Three.pdf shows the
power connector (+13.6, -11), two series resistors on those
power lines, and 8 output lines. Some of the outputs are
10 Mhz. At least one is 1 Mhz.
The center crystal cannister is electrically isolated.
It is on acrylic stand offs. Even the trimmer control
uses a smaller acrylic rod within a larger acrylic
tube/standoff. And the L-shaped piece directly to
the right of the cannister, from which it is supported, is
itself on long standoffs from the right end piece.
There are 3 sets of 4 fine wires coming
out of the crystal cannister, two go to the little board
on the right, one goes to the larger board on the left
(the output board). The crystal cannister was surrounded
with white extruded foam of the same kind as a cheap
picnic cooler.
I removed some of the silver "fingers" around the
crystal cannister area to remove the insulation.
I don't know what the board on the right end does.. maybe
temperature control? The board on the left end seems to be
output buffer/filter.
I don't think I am going to tear this down any further,
and I also don't think I see any easy way for me to adjust
the frequency electronically without ripping into the
crystal cannister and I don't trust my ability to
put it back together in working order.
If you all have suggestions otherwise, fire away.
Chris
Chris, your links don't work.
chris@yipyap.com wrote:
just for show-and-tell:
...
I have four rough pictures.
www.yipyap.com/radio_stuff/ND100M/One.pdf is right (rear)
end of the component side.
www.yipyap.com/radio_stuff/ND100M/Four.pdf is the left (front)
end of the component side.
www.yipyap.com/radio_stuff/ND100M/Two.pdf is a blurry closeup
of the center from the trace side.
www.yipyap.com/radio_stuff/ND100M/Three.pdf shows the
power connector (+13.6, -11), two series resistors on those
power lines, and 8 output lines. Some of the outputs are
10 Mhz. At least one is 1 Mhz.
sorry, revised with correct URL's.
chris@yipyap.com wrote:
just for show-and-tell:
I've been disassembling the Schmomandl ND100M oscillator
block to see if I could use it. I figured, it's the bird
in hand, and once was a high quality piece of equipment
so maybe...
The physical construction is great. Lots of fine pitch
slot head machine screws. Lots of silver plating.
The oscillator unit is long and narrow. It goes
in the 19" rack mount unit in the "depth" direction,
front to back in the upper left hand corner of what
turns out to be a more or less solid block of plated
boxes that make up the whole frequency generator.
Decade controls on the front are switches only. Each
is wired to a decade unit/card and the decade units are
fed signal all in series. Computerish connectors
at the back reproduce the decade switches in some
manner, so the thing can be remotely controlled
for frequency output.
I have four rough pictures.
www.yipyap.com/radio_stuff/ND100M/One.jpg is right (rear)
end of the component side.
www.yipyap.com/radio_stuff/ND100M/Four.jpg is the left (front)
end of the component side.
www.yipyap.com/radio_stuff/ND100M/Two.jpg is a blurry closeup
of the center from the trace side.
power connector (+13.6, -11), two series resistors on those
power lines, and 8 output lines. Some of the outputs are
10 Mhz. At least one is 1 Mhz.
The center crystal cannister is electrically isolated.
It is on acrylic stand offs. Even the trimmer control
uses a smaller acrylic rod within a larger acrylic
tube/standoff. And the L-shaped piece directly to
the right of the cannister, from which it is supported, is
itself on long standoffs from the right end piece.
There are 3 sets of 4 fine wires coming
out of the crystal cannister, two go to the little board
on the right, one goes to the larger board on the left
(the output board). The crystal cannister was surrounded
with white extruded foam of the same kind as a cheap
picnic cooler.
I removed some of the silver "fingers" around the
crystal cannister area to remove the insulation.
I don't know what the board on the right end does.. maybe
temperature control? The board on the left end seems to be
output buffer/filter.
I don't think I am going to tear this down any further,
and I also don't think I see any easy way for me to adjust
the frequency electronically without ripping into the
crystal cannister and I don't trust my ability to
put it back together in working order.
If you all have suggestions otherwise, fire away.
Chris
No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 9.0.814 / Virus Database: 271.1.1/2851 - Release Date: 05/03/10 01:27:00
Hi,
I'm looking for a relatively simple PLL chip
like LMX1501 or similar.
I mean, looking for a new design, that is something
that is easy to source (known to be in production etc)
recent/modern enough to provide a low phase noise.
Is for VHF/UHF below 500MHz application and will
be for MHz steps (no small steps required).
Albeit reasonably low phase noise will be wanted.
What seems to be available from An.Dev. and Nat.Sem.
are way too unnecessarily complex and I would like
it to not have a zilion registers to load via spi.
(might use just a small corner of a CPLD to load it).
Are the simple ones gone obsolete, or simple no longer in the
web pages ???
ok... I think you got the idea...
I'm looking for the basic think...
Any suggestions of what might be usable/available.
Thanks.
Luis Cupido
ct1dmk.
p.s. I know it doesn't matter to have a modern complex one
as some microcontroller will be programming it etc etc...
That I know already ;-) ... no need to tell me :-)
but... if a simple ones exist why should I go complex !
Hi
The complex parts are now the low end. The high end parts have stuff
like sigma delta on them. The 4001 from AD is about as simple as they
get these days.
Bob
On May 4, 2010, at 5:52 AM, Luis Cupido cupido@mail.ua.pt wrot
Hi,
I'm looking for a relatively simple PLL chip
like LMX1501 or similar.
I mean, looking for a new design, that is something
that is easy to source (known to be in production etc)
recent/modern enough to provide a low phase noise.
Is for VHF/UHF below 500MHz application and will
be for MHz steps (no small steps required).
Albeit reasonably low phase noise will be wanted.
What seems to be available from An.Dev. and Nat.Sem.
are way too unnecessarily complex and I would like
it to not have a zilion registers to load via spi.
(might use just a small corner of a CPLD to load it).
Are the simple ones gone obsolete, or simple no longer in the
web pages ???
ok... I think you got the idea...
I'm looking for the basic think...
Any suggestions of what might be usable/available.
Thanks.
Luis Cupido
ct1dmk.
p.s. I know it doesn't matter to have a modern complex one
as some microcontroller will be programming it etc etc...
That I know already ;-) ... no need to tell me :-)
but... if a simple ones exist why should I go complex !
time-nuts mailing list -- time-nuts@febo.com
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and follow the instructions there.
Luis Cupido wrote:
Hi,
I'm looking for a relatively simple PLL chip
like LMX1501 or similar.
I mean, looking for a new design, that is something
that is easy to source (known to be in production etc)
recent/modern enough to provide a low phase noise.
Is for VHF/UHF below 500MHz application and will
be for MHz steps (no small steps required).
Albeit reasonably low phase noise will be wanted.
What seems to be available from An.Dev. and Nat.Sem.
are way too unnecessarily complex and I would like
it to not have a zilion registers to load via spi.
(might use just a small corner of a CPLD to load it).
Are the simple ones gone obsolete, or simple no longer in the
web pages ???
ok... I think you got the idea...
I'm looking for the basic think...
Any suggestions of what might be usable/available.
How about the Peregrine 9701? Pretty low noise, simple (20 bit serial
word to load).. Max reference divider is 63 or 64.
Luis Cupido wrote:
Hi,
I'm looking for a relatively simple PLL chip
like LMX1501 or similar.
I mean, looking for a new design, that is something
that is easy to source (known to be in production etc)
recent/modern enough to provide a low phase noise.
Is for VHF/UHF below 500MHz application and will
be for MHz steps (no small steps required).
Albeit reasonably low phase noise will be wanted.
What seems to be available from An.Dev. and Nat.Sem.
are way too unnecessarily complex and I would like
it to not have a zilion registers to load via spi.
(might use just a small corner of a CPLD to load it).
Are the simple ones gone obsolete, or simple no longer in the
web pages ???
ok... I think you got the idea...
I'm looking for the basic think...
Any suggestions of what might be usable/available.
Thanks.
Luis Cupido
ct1dmk.
Or Fujitsu (e.g. MB15E03SL)
If you're thinking about using a CPLD to load registers in a PLL chip, why not just implement the PLL on the CPLD? After all, if you're looking for simpler-is-better, there's not much on a dedicated PLL chip that you can't easily replicate in CPLD with some care and attention paid to layout.
Date: Tue, 4 May 2010 06:08:56 -0700
From: jimlux@earthlink.net
To: time-nuts@febo.com
Subject: Re: [time-nuts] Simple PLL chips, gone ?
Luis Cupido wrote:
Hi,
I'm looking for a relatively simple PLL chip
like LMX1501 or similar.
I mean, looking for a new design, that is something
that is easy to source (known to be in production etc)
recent/modern enough to provide a low phase noise.
Is for VHF/UHF below 500MHz application and will
be for MHz steps (no small steps required).
Albeit reasonably low phase noise will be wanted.
What seems to be available from An.Dev. and Nat.Sem.
are way too unnecessarily complex and I would like
it to not have a zilion registers to load via spi.
(might use just a small corner of a CPLD to load it).
Are the simple ones gone obsolete, or simple no longer in the
web pages ???
ok... I think you got the idea...
I'm looking for the basic think...
Any suggestions of what might be usable/available.
Thanks.
Luis Cupido
ct1dmk.
Or Fujitsu (e.g. MB15E03SL)
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Nick Foster wrote:
If you're thinking about using a CPLD to load registers in a PLL chip, why not just implement the PLL on the CPLD? After all, if you're looking for simpler-is-better, there's not much on a dedicated PLL chip that you can't easily replicate in CPLD with some care and attention paid to layout.
Most CPLDs don't have low noise phase frequency detectors, the charge
pump, or the analog parts to make the loop filter.
Jim
Thanks for all of your kind encouragement.
I gave up on using the NC100's oscillator for my GPSDO home-lab freq
standard. I was able to find a 10811 oscillator on ebay by
purchasing a non-working 5328A counter with the correct option.
It was very inexpensive and the 10811 appears to be alive.
Now I am reading Time-nuts history and I see that
there is no consensus on which of the popular/published GPSDO
configurations is the best return on effort and expense.
That is rather disappointing.
Any comments on that before I just flip a coin?
Bob Camp wrote:
Hi
Microwave radio suggests low spurs and often low phase noise. That's on top of the stability requirements.
In terms of stability a good Z3801 will run rings around a garden variety Thunderbolt. Both are significantly better on phase noise than a "garden variety" OCXO. You will need a very good OCXO to get to the performance level of either one. The 10811 is probably the easiest thing to both identify and find. You see them selling anywhere from $100 to $200 depending on just how patient you are.
Bob
On May 2, 2010, at 4:13 PM, chris@yipyap.com wrote:
Bob asks a reasonable question:
What kind of accuracy are you trying to obtain?
Bob
I would like to end up with something that is usable
on a home electronics workbench. Something like a
Z3801. Something I can use if I ever try to do some
goofing around with microwave radio operation.
I'm not serious enough to want to spend hundreds
on a working unit. On the other hand, lashing up
something that works would count toward my
hobby/education so then it is ok to spend a little
bit of money.
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No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 9.0.814 / Virus Database: 271.1.1/2849 - Release Date: 05/02/10 01:27:00
Hi
The gotcha is that the Z38xx and TBolt do a pretty good job.
To do as well:
- Build a counter with a < 1 ns resolution to compare the pps ticks. You want the resolution to be below the floor of a good timing receiver.
- Set up a roughly 20 bit D/A to drive the EFC. More bits are always better. You can get away with 16 bits and tweaking fairly often. The objective is a LSB in the parts in 10^-13.
- Put a good reference on the D/A. Voltage tuning on the EFC makes this tough to get around.
- Set up a PIC or micro of your choice (Coldfire works quite well). You can get a lot of processor for $5 these days.
- Probably lay out a pcb to put everything on.
Hook that all up to a good modern high sensitivity 12 channel timing grade GPS and start tuning your loop. You will need a good local reference to really get the tuning right.
This is in addition to the usual divide to 1 pps on the 10811, buffering of outputs, power supplies and regulation, and packaging.
Software wise, most people seem to wind up with some sort of software PID, possibly with coefficients that change as the unit stabilizes (Z38xx family) or not (TBolt ?).
Lots of work to get to "as good as". Of course you will be as good as the combined performance of the two, which is indeed better than either one by it's self.
Bob
On May 16, 2010, at 5:30 PM, chris@yipyap.com wrote:
Thanks for all of your kind encouragement.
I gave up on using the NC100's oscillator for my GPSDO home-lab freq standard. I was able to find a 10811 oscillator on ebay by
purchasing a non-working 5328A counter with the correct option.
It was very inexpensive and the 10811 appears to be alive.
Now I am reading Time-nuts history and I see that
there is no consensus on which of the popular/published GPSDO
configurations is the best return on effort and expense.
That is rather disappointing.
Any comments on that before I just flip a coin?
Bob Camp wrote:
Hi
Microwave radio suggests low spurs and often low phase noise. That's on top of the stability requirements.
In terms of stability a good Z3801 will run rings around a garden variety Thunderbolt. Both are significantly better on phase noise than a "garden variety" OCXO. You will need a very good OCXO to get to the performance level of either one. The 10811 is probably the easiest thing to both identify and find. You see them selling anywhere from $100 to $200 depending on just how patient you are.
Bob
On May 2, 2010, at 4:13 PM, chris@yipyap.com wrote:
Bob asks a reasonable question:
What kind of accuracy are you trying to obtain?
Bob
I would like to end up with something that is usable
on a home electronics workbench. Something like a
Z3801. Something I can use if I ever try to do some
goofing around with microwave radio operation.
I'm not serious enough to want to spend hundreds
on a working unit. On the other hand, lashing up
something that works would count toward my
hobby/education so then it is ok to spend a little
bit of money.
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.
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and follow the instructions there.
No virus found in this incoming message.
Checked by AVG - www.avg.com Version: 9.0.814 / Virus Database: 271.1.1/2849 - Release Date: 05/02/10 01:27:00
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Parts for the Brooks Sheera W5OJM design are getting hard to find also need the extra divider mod for the 10 Mhz OCXO
The James Miller G3RUH design is popular for simple if you have the right GPS receiver with 100Khz out.
VE2ZAZ design has a few issues with ground loops ( a fix is out there) and using the same buffer for all outputs, may also need a buffer amp for the 10811, another mod would be a separate voltage regulator for the ECC voltage.
I think all three designs would fall short for most on the list, but for me it is hard to tell the difference.
Did you have another design in mind ?
Stanley
<snip>Now I am reading Time-nuts history and I see that
there is no consensus on which of the popular/published GPSDO
configurations is the best return on effort and expense.
That is rather disappointing.
Any comments on that before I just flip a coin?
<snip>
Hi
Part of the issue is that some of the thinking on GPSDO's dates back to the era of selective availability on GPS. Designs from that era need to be upgraded to really get them to be all they can be with SA turned off.
Bob
On May 16, 2010, at 9:19 PM, Stanley Reynolds wrote:
Parts for the Brooks Sheera W5OJM design are getting hard to find also need the extra divider mod for the 10 Mhz OCXO
The James Miller G3RUH design is popular for simple if you have the right GPS receiver with 100Khz out.
VE2ZAZ design has a few issues with ground loops ( a fix is out there) and using the same buffer for all outputs, may also need a buffer amp for the 10811, another mod would be a separate voltage regulator for the ECC voltage.
I think all three designs would fall short for most on the list, but for me it is hard to tell the difference.
Did you have another design in mind ?
Stanley
<snip>Now I am reading Time-nuts history and I see that
there is no consensus on which of the popular/published GPSDO
configurations is the best return on effort and expense.
That is rather disappointing.
Any comments on that before I just flip a coin?
<snip>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,
there is a modified W5OJM GPSDO and all the PCB and so on......please see the flwng link
http://pagesperso-orange.fr/f5cau/base_temps_gps_f5cau/page_basegpsF5CAU.htm
Basically a well designed mods of the above idea.......and no special parts..... and it runs from 10MHz.....
Rgds Ernie.
-----Original Message-----
From: Bob Camp lists@rtty.us
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Mon, May 17, 2010 3:40 am
Subject: Re: [time-nuts] GPSDO - was - oscillator choice question
Hi
Part of the issue is that some of the thinking on GPSDO's dates back to the era
f selective availability on GPS. Designs from that era need to be upgraded to
eally get them to be all they can be with SA turned off.
Bob
n May 16, 2010, at 9:19 PM, Stanley Reynolds wrote:
Parts for the Brooks Sheera W5OJM design are getting hard to find also need
he extra divider mod for the 10 Mhz OCXO
The James Miller G3RUH design is popular for simple if you have the right GPS
eceiver with 100Khz out.
VE2ZAZ design has a few issues with ground loops ( a fix is out there) and
sing the same buffer for all outputs, may also need a buffer amp for the 10811,
nother mod would be a separate voltage regulator for the ECC voltage.
I think all three designs would fall short for most on the list, but for me it
s hard to tell the difference.
Did you have another design in mind ?
Stanley
<snip>Now I am reading Time-nuts history and I see that
there is no consensus on which of the popular/published GPSDO
configurations is the best return on effort and expense.
That is rather disappointing.
Any comments on that before I just flip a coin?
<snip>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.
ime-nuts mailing list -- time-nuts@febo.com
o unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
nd follow the instructions there.