Re: [Elecraft] GPS Disciplined 10MHZ source from China

[David Anderson via Elecraft]

The advantage of the Leo Bodnar unit is that it can do a lot more than just act 
as a fixed 10 MHz reference. It covers the range 450 Hz to 800 MHz, so has many 
other uses around the shack. 
I use mine for frequency locking the 116 MHz Local oscillator of an a G4DDK 
Anglian 144 MHz transverter. 

If it is just a 10 MHz reference that is required then other units with better 
phase noise are available surplus, though be careful as some may require a bit 
of work if they are very old, however the Chinese do make some very nice 10 MHz 
GPSDO's which are reasonably priced. I have one and a matching 8 output 
distribution amplifier which also contains a fallback OCXO within it. I also 
have a surplus HP Z3801A, it is large, requires a 48V DC power supply, I use it 
as my main 10 MHz shack and lab reference for microwave counters. 

The Leo Bodnar can be switched on and is locked and stable in about a minute 
from cold, unlike high accuracy GPSDOs with OCXOs which can take 15 to 30 
minutes to reach lock and really are designed to be left switched on and 
consuming power all the time, so that may be a consideration in a ham station 
that is not always attended and you want to power everything down for safety or 
to save electricity.

Lastly if you want a very nice shack GPS time clock. I recently found this USA 
kit on Tindie.

https://www.tindie.com/products/nsayer/gps-clock/

It is a digital LED clock which is GPS locked. Note it isn't a frequency 
reference, only a timepiece.
It can display hours minute and seconds plus optionally tenths of a second.

All on one PCB and runs from 5V DC at about 200mA max. I built one and am most 
impressed. You can have it show local time with auto DST correction, 12 or 24 
hour format, or leave it on UTC for the shack. I have not noticed any RFI from 
it, even in its wooden enclosure.

It does require a GPS Lock to work, so if you live in a basement, unless you 
mount an antenna outside it won't work. From a cold start it takes about a 
couple of minutes to lock, sometimes less. I leave mine on as the power 
consumption is relatively low.

I have no connection with the designer, other than as a customer.


73 from David GM4JJJ

On 9 May 2017, at 15:19, Paul Christensen  wrote:

>> "If you want a good quality 10 MHz GPSDO, I recommend the one made by Leo
> Bodnar M0XER. It was reviewed in QST, June 2016."
> 
> Unless the K3S architecture is different than the K3, then frequency, rather
> than phase-locking is used from the external frequency source.  Phase noise
> performance of the GPS-DO doesn't impact performance of the K3 receiver.
> 
> However, if planning on distributing the GPS-DO to other devices, I think
> it's worthwhile to note that the higher-priced version of the Bodnar is
> still > 30 dB worse at a 100 Hz Fc offset than a common Trimble Thunderbolt
> with the Trimble-branded OCXO (not Piezo) when powered from a low-noise,
> lab-grade supply.  For example, typical Trimble PN at 100 Hz is -160 dBc.
> The upper-grade Bodnar unit is about -125 dBc.  
> 
> Compared to what's available on the new and used markets, I agree with G4DYA
> that the Bodnar's performance is probably characterized as good, but not
> excellent.  Again, for K3 users it isn't an issue, but if the device is
> driving other test gear or other transceivers, that 30 dB difference may
> mean a lot.  
> 
> The Thunderbolts were once plentiful on eBay for USD $99.  Scarcity has
> driven that up but with persistence, a watchful eye can still spot one at a
> reasonable price.   
> 
> I ended up installing a Trimble unit and Lambda linear supply into a
> customized enclosure.  It drives a TAPR distribution amp and that supplies a
> precision 10 MHz refence to multiple transceivers and test equipment.  
> 
> http://tinyurl.com/j7r36w5
> 
> Paul, W9AC
> 
> 
> 
> 
> 
> 
> 
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Re: [Elecraft] GPS Disciplined 10MHZ source from China

[Wes Stewart]

Two Christmases ago, my fiance asked me what I wanted for a gift.  On a whim, 
without too much study, I said a Bodnar GPSDO.  I emailed Leo and inquired about 
using the unit as a reference for my SDR-IQ (66. MHz) and a 10 MHz source 
for my DG8SAQ network analyzer which can also operate as a frequency counter.


He sent me a screen shot of the software display that showed the variables that 
determine the two frequencies.  Unfortunately, the calculations to set different 
frequencies are obscure.  After several inquiries (after the purchase) he sent 
me a link to the internal device data sheet (Silicon Labs Si5328) for me to 
decipher.  QST had this to say about that:


"A couple of caveats: there is currently
no documentation for the unit other than
what Bill Hein has provided on the Force
12 website, and no schematic. Bodnar is
working on an improved version of the
setup software, and documentation may
follow, but I was not able to test the updated
software"

In reality, there is no updated software and Force 12 is gone.

Summary:

I believe the hardware is fine, however the documentation and communication with 
Leo, after the purchase but not before, is iffy.


When locked to GPS it's an excellent frequency reference.  When unlocked, it's a 
TCXO and not so good. Phase noise isn't stellar.


It's a frequency standard and not a time standard. If you want to set your clock 
use WWV or NTP.


Wes  N7WS


On 5/9/2017 1:41 AM, Richard Lamont wrote:


If you want a good quality 10 MHz GPSDO, I recommend the one made by Leo
Bodnar M0XER. It was reviewed in QST, June 2016.

https://leobodnar.com/

73,
Richard G4DYA



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Re: [Elecraft] GPS Disciplined 10MHZ source from China

[Dave B via Elecraft]

OK, so what was the "Item Number" on the bay?   As I'm unable to find
that seller to see what exactly it was you purchased.

Or, what is the make/model number of it (if it's an ex commercial item,
such as a Thunderbolt.)

The devil is in the detail with these things.

73
Dave G0WBX


On 09/05/17 21:53, elecraft-requ...@mailman.qth.net wrote:
> Date: Mon, 8 May 2017 16:26:10 -0600
> From: "Jay Miller" <jayfmil...@mindspring.com>
> To: <elecraft@mailman.qth.net>
> Subject: [Elecraft] GPS Disciplined 10MHZ source from China
> Message-ID: <001001d2c84a$1881a390$4984eab0$@mindspring.com>
> Content-Type: text/plain; charset="us-ascii"
>
> I was curious so I bought a GPS disciplined 10MHz source from China using
> the eBay seller "cybereveryday."  I have a calibrated scope and a Rubidium
> 10MHz source. I noticed a frequency offset on three of the WWV frequencies
> when I plugged it into the K3 XREF module after getting "GPS Lock" rather
> than using my Rubidium lamp standard   I measured the 10MHz output from the
> GPSDO and it is 10,000,025 Hz. (2.5 PPM) The eBay ad states "Accuracy: than
> above OXCO 2 order of magnitude."  The point is, even using the K3 zero-beat
> method with 15 MHz WWV I can get closer to being dead on frequency than
> using this Chinese mfg. GPSDO. Again, Elecraft quality and engineering WINS.
>
>  
>
> Jay Miller, N4NUI

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Re: [Elecraft] GPS Disciplined 10MHZ source from China

[Mark Goldberg]

Thanks for bringing up phase noise. From my research on other cheap devices
(knockoff TCXOs), I have found that phase noise was obviously not
considered and in that case was truly awful. It was in the -115 dBc range
at 100hz, but, likely due to poor design, actually rose to -110 dBc at
10-100 kHz offset, which is truly awful. There were also many spurs. If
something is not specified, it is likely not even considered.

I had not realized a Trimble Thunderbolt was so good. I have been using the
output of the low aging rate option of an HP8642A for a 10 MHz reference,
no idea of the phase noise. Now you have me wanting something else!

73,

Mark
W7MLG

On Tue, May 9, 2017 at 7:19 AM, Paul Christensen  wrote:

> >"If you want a good quality 10 MHz GPSDO, I recommend the one made by Leo
> Bodnar M0XER. It was reviewed in QST, June 2016."
>
> Unless the K3S architecture is different than the K3, then frequency,
> rather
> than phase-locking is used from the external frequency source.  Phase noise
> performance of the GPS-DO doesn't impact performance of the K3 receiver.
>
> However, if planning on distributing the GPS-DO to other devices, I think
> it's worthwhile to note that the higher-priced version of the Bodnar is
> still > 30 dB worse at a 100 Hz Fc offset than a common Trimble Thunderbolt
> with the Trimble-branded OCXO (not Piezo) when powered from a low-noise,
> lab-grade supply.  For example, typical Trimble PN at 100 Hz is -160 dBc.
> The upper-grade Bodnar unit is about -125 dBc.
>
> Compared to what's available on the new and used markets, I agree with
> G4DYA
> that the Bodnar's performance is probably characterized as good, but not
> excellent.  Again, for K3 users it isn't an issue, but if the device is
> driving other test gear or other transceivers, that 30 dB difference may
> mean a lot.
>
> The Thunderbolts were once plentiful on eBay for USD $99.  Scarcity has
> driven that up but with persistence, a watchful eye can still spot one at a
> reasonable price.
>
> I ended up installing a Trimble unit and Lambda linear supply into a
> customized enclosure.  It drives a TAPR distribution amp and that supplies
> a
> precision 10 MHz refence to multiple transceivers and test equipment.
>
> http://tinyurl.com/j7r36w5
>
> Paul, W9AC
>
>
>
>
>
>
>
> ---
> This email has been checked for viruses by Avast antivirus software.
> https://www.avast.com/antivirus
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[Elecraft] GPS Disciplined 10MHZ source from China

[Paul Christensen]

>"If you want a good quality 10 MHz GPSDO, I recommend the one made by Leo
Bodnar M0XER. It was reviewed in QST, June 2016."

Unless the K3S architecture is different than the K3, then frequency, rather
than phase-locking is used from the external frequency source.  Phase noise
performance of the GPS-DO doesn't impact performance of the K3 receiver.

However, if planning on distributing the GPS-DO to other devices, I think
it's worthwhile to note that the higher-priced version of the Bodnar is
still > 30 dB worse at a 100 Hz Fc offset than a common Trimble Thunderbolt
with the Trimble-branded OCXO (not Piezo) when powered from a low-noise,
lab-grade supply.  For example, typical Trimble PN at 100 Hz is -160 dBc.
The upper-grade Bodnar unit is about -125 dBc.  

Compared to what's available on the new and used markets, I agree with G4DYA
that the Bodnar's performance is probably characterized as good, but not
excellent.  Again, for K3 users it isn't an issue, but if the device is
driving other test gear or other transceivers, that 30 dB difference may
mean a lot.  

The Thunderbolts were once plentiful on eBay for USD $99.  Scarcity has
driven that up but with persistence, a watchful eye can still spot one at a
reasonable price.   

I ended up installing a Trimble unit and Lambda linear supply into a
customized enclosure.  It drives a TAPR distribution amp and that supplies a
precision 10 MHz refence to multiple transceivers and test equipment.  

http://tinyurl.com/j7r36w5

Paul, W9AC

 





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Re: [Elecraft] GPS Disciplined 10MHZ source from China

[Richard Lamont]

On 08/05/17 23:26, Jay Miller wrote:
> I was curious so I bought a GPS disciplined 10MHz source from China using
> the eBay seller "cybereveryday."  I have a calibrated scope and a Rubidium
> 10MHz source. I noticed a frequency offset on three of the WWV frequencies
> when I plugged it into the K3 XREF module after getting "GPS Lock" rather
> than using my Rubidium lamp standard   I measured the 10MHz output from the
> GPSDO and it is 10,000,025 Hz. (2.5 PPM) The eBay ad states "Accuracy: than
> above OXCO 2 order of magnitude."  The point is, even using the K3 zero-beat
> method with 15 MHz WWV I can get closer to being dead on frequency than
> using this Chinese mfg. GPSDO. Again, Elecraft quality and engineering WINS.

If you want a good quality 10 MHz GPSDO, I recommend the one made by Leo
Bodnar M0XER. It was reviewed in QST, June 2016.

https://leobodnar.com/

73,
Richard G4DYA


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Re: [Elecraft] GPS Disciplined 10MHZ source from China

[Wes Stewart]

How did you measure the GPSDO?  Against the Rubidium?

On 5/8/2017 3:26 PM, Jay Miller wrote:

I was curious so I bought a GPS disciplined 10MHz source from China using
the eBay seller "cybereveryday."  I have a calibrated scope and a Rubidium
10MHz source. I noticed a frequency offset on three of the WWV frequencies
when I plugged it into the K3 XREF module after getting "GPS Lock" rather
than using my Rubidium lamp standard   I measured the 10MHz output from the
GPSDO and it is 10,000,025 Hz. (2.5 PPM) The eBay ad states "Accuracy: than
above OXCO 2 order of magnitude."  The point is, even using the K3 zero-beat
method with 15 MHz WWV I can get closer to being dead on frequency than
using this Chinese mfg. GPSDO. Again, Elecraft quality and engineering WINS.

  


Jay Miller, N4NUI


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Re: [Elecraft] GPS Disciplined 10MHZ source from China

[Harry Yingst via Elecraft]

Mine is from G3RUH http://www.jrmiller.demon.co.uk/projects/ministd/frqstd.htm

he states: The stability as given by the Allan Deviation is typically 5x10-12 
at τ=10s.
That figure is 0.05 Hz at 10 GHz and is a remarkably small value.


Using mine as a example I would say the one you have is way off.

I'm not sure what you are using for an Antenna, I'm using an external GPS 
Timing Antenna



From: Jay Miller <jayfmil...@mindspring.com>
To: elecraft@mailman.qth.net 
Sent: Monday, May 8, 2017 6:28 PM
Subject: [Elecraft] GPS Disciplined 10MHZ source from China



I was curious so I bought a GPS disciplined 10MHz source from China using

the eBay seller "cybereveryday."  I have a calibrated scope and a Rubidium

10MHz source. I noticed a frequency offset on three of the WWV frequencies

when I plugged it into the K3 XREF module after getting "GPS Lock" rather

than using my Rubidium lamp standard  I measured the 10MHz output from the

GPSDO and it is 10,000,025 Hz. (2.5 PPM) The eBay ad states "Accuracy: than

above OXCO 2 order of magnitude."  The point is, even using the K3 zero-beat

method with 15 MHz WWV I can get closer to being dead on frequency than

using this Chinese mfg. GPSDO. Again, Elecraft quality and engineering WINS.




Jay Miller, N4NUI



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Re: [Elecraft] GPS Disciplined 10MHZ source from China

[Clay Autery]

Need to get that TMP cable (radio to Freq. Ctr) made and get back to the
project of determining exactly how close you can get on average without
an instrument(s).

Pretty sure I can get a lot closer than 25 Hz using my ear even my
old aviator's ear.

Glad I chose NOT to try the eBay/Chinese PCB box deals...

__
Clay Autery, KY5G

On 5/8/2017 5:26 PM, Jay Miller wrote:
> I was curious so I bought a GPS disciplined 10MHz source from China using
> the eBay seller "cybereveryday."  I have a calibrated scope and a Rubidium
> 10MHz source. I noticed a frequency offset on three of the WWV frequencies
> when I plugged it into the K3 XREF module after getting "GPS Lock" rather
> than using my Rubidium lamp standard   I measured the 10MHz output from the
> GPSDO and it is 10,000,025 Hz. (2.5 PPM) The eBay ad states "Accuracy: than
> above OXCO 2 order of magnitude."  The point is, even using the K3 zero-beat
> method with 15 MHz WWV I can get closer to being dead on frequency than
> using this Chinese mfg. GPSDO. Again, Elecraft quality and engineering WINS.
>
> Jay Miller, N4NUI
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[Elecraft] GPS Disciplined 10MHZ source from China

[Jay Miller]

I was curious so I bought a GPS disciplined 10MHz source from China using
the eBay seller "cybereveryday."  I have a calibrated scope and a Rubidium
10MHz source. I noticed a frequency offset on three of the WWV frequencies
when I plugged it into the K3 XREF module after getting "GPS Lock" rather
than using my Rubidium lamp standard   I measured the 10MHz output from the
GPSDO and it is 10,000,025 Hz. (2.5 PPM) The eBay ad states "Accuracy: than
above OXCO 2 order of magnitude."  The point is, even using the K3 zero-beat
method with 15 MHz WWV I can get closer to being dead on frequency than
using this Chinese mfg. GPSDO. Again, Elecraft quality and engineering WINS.

 

Jay Miller, N4NUI

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