[Elecraft] [KX3] JT65-HF KX3 Freq Drift Measurements

[Edward R Cole]

Gary,

I made frequency drift curves simulating JT65 by keying my KX3 at 5w 
CW on 50-MHz for 50-seconds and measuring frequency every ten seconds 
with a EIB-538 counter that uses a TCXO reference or can use my 
Rubidium standard as ext ref.  This offers +/-5 E-11 
accuracy.  Greatest error was 108 Hz before I ran temp compensation 
procedure.  After ward the max drift was about 9-Hz.  The data at 
10-seconds in the tests after temp compensation are aberrant and I 
suspect something happened in the temp comp procedure to record a bad offset.
http://www.kl7uw.com/KX3_FREQ_DRIFT_TABLE.pdf

I think this really supports how well the temp compensation procedure 
performs.  I think you will find much better drift characteristics 
after running it.  I have added a heat sink on my KX3 since making these tests.

I find that drift of up to 20-Hz in one minute is acceptable for 
JT65B which I uses on eme.  My K3+DEMI transverter drifts about +7-Hz 
and then stays near that offset for running past 30-minutes of JT65 
on 2m.  The KX3 is not as good but is acceptable.  Note I run my K3 
with an EXREF on 28-MHz seeing about +2 Hz error (but am running at 
0-dBm in transverter mode so no extra heat results when transmitting).

----snipped
For those that have done similar tests on an uncompensated KX3, do these
results seem reasonable?  If they are reasonable is it safe to say that
successful 6m JT65/JT9 operation even after extended temperature
compensation is unlikely?

73's Gary K6YOA


73, Ed - KL7UW
http://www.kl7uw.com
     "Kits made by KL7UW"
Dubus Mag business:
     dubususa at gmail.com