[Elecraft] Subject: Re: Installed K3EXREF

[Edward R. Cole]

Dan,

Sorry for delay in reply, I get the Elecraft reflector by digest.

I believe it will work with the standard TCXO but there was a note 
from Elecraft recommending that the TCXO-3 be installed for use with 
the K3EXREF.  Perhaps that e-mail can be retrieved from the digest, 
Napple, etc.

I ordered the TCXO-3 with my K3 so all testing was done with it installed.

The K3EXREF corrects the TCXO error periodically but The TCXO drift 
is not affected in between times so probably one would experience 
more drift with the TCXO vs the TCXO-3.  I suppose this could cause 
(?) a more abrupt freq. shift when the EXREF performs the 
correction.  This is really a question to ask the Elecraft guys.

My experience with the TCXO-3 + K3EXREF is the drift is minimal and 
often does not amount to even 1-Hz between times the K3EXREF samples 
the freq. (so I do not see a change in the TCXO-3 that often - after 
the initial 20-30 minutes warm-up).  During warm up the K3EXREF 
generates repeated corrections to the TCXO-3 frequency stabilizing at 
about 49.380.070.  This is supposedly due in part to xtal aging in my 
TCXO-3 (now over a year old).  But checking actual radio frequency 
accuracy (say on 14-MHz) during the warm-up period the frequency 
error is never more than 2-Hz with my frequency counter (locked to a 
rubidium).

With the K3EXREF installed you can monitor the offset on CONFIG: 
REF*CAL  (the asterisk blinks when the EXREF is running).  Without 
the K3EXREF CONFIG: REF CAL permits entry of a fixed offset (useful 
for running a transverter that may not be exact in frequency) or for 
those that like to tweak such things ;-)  The manual offset feature 
is defeated when running the K3EXREF.

73, Ed - KL7uW

------------------------------

Message: 8
Date: Fri, 20 May 2011 19:47:33 -0700 (PDT)
From: Dan AE9K <AE9K at pkts.net>
Subject: Re: [Elecraft] Installed K3EXREF
To: elecraft at mailman.qth.net
Message-ID: <1305946053762-6388532.post at n2.nabble.com>
Content-Type: text/plain; charset=us-ascii

Ed,

Thanks for the response.  Let me clarify my question.  I'm wondering if the
KTCXO3 0.5 ppm oscillator can be omitted and still get great results with
the K3EXREF and the standard 5 ppm oscillator.  This is of interest because
I intend to acquire the K3EXREF but do not have the KTCXO3 and would prefer
not to buy it if it doesn't add any benefit.

My logic: If the K3EXREF adjusts the TCXO (via REF CAL) every 4 seconds,
then why not let it adjust the standard K3 TCXO instead of having it adjust
the optional KTCXO3 oscillator?

Even though the two oscillators differ by an order of magnitude in their
error, does that error make a difference when the K3EXREF adjustments are
every four seconds?

ps - During your beta testing were you using the standard K3 5 ppm
oscillator or the KTCXO3 0.5 ppm oscillator?  I didn't find mention of that
on your web site.

Dan
AE9K




73, Ed - KL7UW, WD2XSH/45
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