[Elecraft] K3EXREF query

[Bayard Coolidge, N1HO]

>>> Upon further reading, the corrections of this module appear to be in  ~1Hz steps.
>>>  I was more interested in something that disciplines the oscillator in a finer more continuous way.

I have a K3EXREF on order from Aptos, as well as a Trimble Thunderbolt coming via E-Bay.

The Trimble Thunderbolt produces two outputs, a 10.000000 MHz sine wave and a 1 pps pulse.
The 10MHz sine wave will be sent to the EXREF, which will then use that to phase-lock an
oscillator internal to the K3. I'll leave it to you to study the EXREF installation/user's manual as
well as the K3 schematics (which are downloadable from the Elecraft web site) to see precisely how
that's done. But from what I've read so far, if you want sub-Hertz accuracy for the FMTs, etc., you'll
need to zero-beat to WWV, count your nulls, and then calculate and apply a correction factor to your
measurements. Otherwise, you're going to be looking at some very long integration times to ensure
that your local oscillator is at 10.0000000 MHz (or whatever). There may be some newer devices out
there that output a higher frequency reference signal, and if so, I suspect that they would be very, very
expensive. My informal research indicates that the Thunderbolt listed at around $1200-$1500 new
10+ years ago, and obviously used ones on E-Bay are much less expensive, but if you were looking
for something better than that (a rubidium or cesium oscillator?), the cost will be considerably higher. 

K5CM has published a couple of interesting papers at his website, http://k5cm.com, and KE5FX's
Lady Heather's disciplined oscillator control program web page helps explain some of the short- and long-term
frequency tolerance issues at http://www.thegleam.com/ke5fx/heather/readme.htm which would
be well worth your while to study.

Another good source of information for you might be the Time Nuts: http://www.leapsecond.com/time-nuts.htm

Hope that helps!

73,

Brandy, N1HO




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