[Elecraft] K3 Frequency Shift

[Edward R. Cole]

Mike,

I was one of the beta-testers of the K3EXREF and see about a move 
from 49.380 to 49.380.080 over about an hour from cold start.  Then 
is settles down to moving only in single digit amounts.  MY 10-MHz 
reference is a surplus OCXO (oven controlled xtal osc) rated at +/- 5 
E-12  which holds the K3 to within +/- 2 Hz at 28-MHz.  The error is 
proportional to frequency so error is < 1Hz at 20m and below.  On 6m 
it runs between 2-Hz and 3-Hz error measured on my mw frequency 
counter locked to a Rubidium standard.  You can view my complete 
beta-test report on the EXREF at:
http://www.kl7uw.com/K3EXREF.htm
----------------
Date: Sun, 29 Apr 2012 06:58:42 -0700
From: Matt Zilmer <mzilmer at verizon.net>
Subject: Re: [Elecraft] K3 Frequency Shift
To: Mike Harris <mike.harris at cwimail.fk>
Cc: elecraft at mailman.qth.net
Message-ID: <62iqp7l39asr4eh8abo3h36g64m6q5u7np at 4ax.com>
Content-Type: text/plain; charset=ISO-8859-1


 >It would be interesting if someone with an EXTREF board installed would
 >post the change in REF CAL number from cold to hot and extended run.

For K3 #24, w/EXTREF:
Cold start:  49.379.774 is typical;
After ~2 hours warmiing up:  49.379.693 is typical.
The EXTREF here is driven by a Trimble Thunderbolt-based GPSDO.




73, Ed - KL7UW, WD2XSH/45
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