[Elecraft] K3EXREF Questions

[Edward R. Cole]

And if you want to save about $50, there are several OCXO on e-bay 
for $40-50 (with many offering free shipping).  All you do is hook 
them to 12vdc and coax to the K3EXREF, as most run at +10 dBm.  The 
waveform may not be a perfect sine wave.

--and no satellites were harmed in locking your K3! ;-)

My Russian surplus OCXO is rated +/- 5E-12 (phase noise = -150 dBc/Hz 
at 1-KHz) and runs full time.  I also have a Rb, but reserve its use 
for critical freq. measurements.

Phase noise is not an issue when running the K3EXREF as that is 
established by the K3 TCXO.  The external reference serves only to 
correct TCXO freq. drift every 4-seconds or so.
---------------------------
Another good choice is the Trimble Thunderbolt receiver.  There are a
lot of these refurbished units available on eBay or elsewhere for
under $100.  You can leave this receiver on full-time if necessary (I
do).  The Thunderbolt outputs a sine wave at 12.5 dBm.

I used an Rb standard borrowed from work for a few days, and found
that the Thunderbolt and Rb produced about the same amount of
precision.  The Rb is noisier though (in the time domain), looking at
its output on a spectrum analyzer.  You can't beat an OCXO for
cleanliness....


73,
Matt W6NIA



73, Ed - KL7UW, WD2XSH/45
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