Re: GPS Disciplined 10MHZ source from China

Posted by Elecraft mailing list on May 11, 2017; 8:01am
URL: http://elecraft.85.s1.nabble.com/GPS-Disciplined-10MHZ-source-from-China-tp7630465p7630500.html

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 <[hidden email]> 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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