[Elecraft] Installed K3EXREF

[Edward R. Cole]

Rick,

For the majority who only do CW/SSB on HF, adding the EXREF is 
probably unnecessary.  The TCXO-3 holds the K3 within 14-Hz on 
28-MHz.  The EXREF improves that by an order of magnitude to 1.4 Hz.

This becomes necessary for some digital modes like JT-65.  That is 
mainly used on eme on 144 and higher bands.  If you operate on the 
microwave bands oscillator error is mulitplied so that is becomes 
hard to get much freq. accuracy or stability.  On 1296 I use a 
transverter that has an external locked PLL LO.  That keeps it within 
1-Hz.  Typically one would not have better than a few KHz with a xtal 
oscillator on 105.67 MHz multiplied x12 = 1268 MHz.  Getting the 
accuracy on the transverter LO without also having it on 28-MHz IF 
radio is kind of being only "Half-done".  With the K3 EXREF my 
combined 1296 freq. will equal that of the K3.  That is important 
when eme signals are so weak they cannot be detected by ear.  Add 
frequency errors to that and the task becomes very tough.

Now consider doing that at 10-GHz.  A few of us with K3's are mw'ers 
and/or eme'rs so the accuracy is very important to us.

Sidenote:  Use of 10-MHz WWV is nearly impossible if you run a 10-MHz 
station reference oscillator.  I have a mw freq.counter that uses a 
rubidium external reference.  I use it to check the frequency of my 
10-MHz OCXO which I run thru a 4-way distribution amp to feed things 
in the shack:
1) K3EXTREF
2) 144/28 Transverter (DEMI)
3) 1296/28 Transverter (DEMI)
4) future item

The OCXO was bought off e-bay for $39.99+shipping, and is very 
stabile but does drift over months so I "tweak" it back to the 
Rubidium about 4 times a year.  It runs 24/7 on a battery supply 
floated by a charger.

All can be seen on my website (including newly added instructions for 
adding sub-Rx IF Out).
73, Ed - KL7UW

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Message: 33
Date: Sun, 20 Mar 2011 14:45:59 +0000
From: Rick Stealey <rstealey at hotmail.com>
Subject: Re: [Elecraft] Installed K3EXREF
To: <elecraft at mailman.qth.net>

Excellent posting by W9AC, a great reference, to be saved.
Now I wonder if it would be possible for someone to enlighten me as to
the need for such extreme accuracy?  Is it because my K3 reads out to 1 Hz
but I can't really believe the absolute accuracy of that number unless I
get a K3EXREF?  But if that is the case, my question would still remain,
wouldn't it?
Not that I need something else to put on my list ahead of my P3 and
sub receiver.
Rick  K2XT



73, Ed - KL7UW, WD2XSH/45
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BP40IQ   500 KHz - 10-GHz   www.kl7uw.com
EME: 144-1.4kw, 432-100w, 1296-testing*, 3400-winter?
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