[Elecraft] KX3: thermal frequency drift

[Matt VK2RQ]

You are right, you can't use WWV for the temperature compensation data collection procedure itself. However, we are talking about the reference calibration that you must perform after the temperature compensation data collection -- for that, you need a precisely known frequency reference. Ed below said he was using his XG3 for that, but it was drifting around 2Hz or so. I was saying that you can do better than that by zero-beating with WWV, even with Doppler shift error. Note that when I say "zero beat", I don't mean tuning the carrier down to "0Hz" (that topic has been beaten to death, so I won't repeat it here :-) ).

73,
Matt VK2RQ

> On 12 Apr 2014, at 8:03 am, Oliver Dröse <droese at necg.de> wrote:
> 
> 
> As you need to do the extend temp procedure at +/- 50 MHz that's no option, Matt.
> 
> @Ed:
> The K3 will work fine as source for the ext. temp. procedure. Just turn it down to lowest power or use the transverter out port.
> 
> 73, Olli - DH8BQA
> 
> Contest, DX & radio projects: http://www.dh8bqa.de
> 
> 
> 
> Am 11.04.2014 23:58, schrieb Matt VK2RQ:
>> You are probably better off zero-beating to WWV. You should easily be able to get within 500mHz or less.
>> 
>> 73,
>> Matt VK2RQ
>> 
>>> On 12 Apr 2014, at 6:39 am, Edward R Cole <kl7uw at acsalaska.net> wrote:
>>> 
>>> It was suggested I do the Temp Compensation Procedure.  Unfortunately I do not have a stable 50-MHz signal source. However I did run the Reference Frequency Calibration using my XG3.  Call this "Part Two":
>>> 
>>> I sampled the RF output of the XG3 with my counter and also input that to the KX3 for the Calib.  This required running at 0 dBm to inject strong enough signal for the counter (approx -3 dBm).  I turned on the ATT for the KX3 to keep input from overdriving.  Got about S9 signal level.
>>> 
>>> I got it adjusted to within about 2-Hz.  The XG3 drifts approx +/- 2 Hz so difficult to set the Ref*Frequency using it.  But that eliminated most of the 38 Hz offset I saw last night.  Running the Tx at 5w afterward drift was in the range of 0 to +7 Hz for a 50-second key down run.  The drift is not steady in one direction so average error is probably in the neighborhood of +5 Hz with 5-Hz uncertainty in the measurement.  Crude but gives a ballpark idea what to expect.
>>> 
>>> Today's measurements were all with new heat sink installed.  Temp Comp. probably would lower these numbers a bit.
>>> 
>>> I might try running my K3 as signal source for Temp Comp. if it holds more stable then the XG3 at 50-MHz.  I am using the EXREF so it may be better?
>>> 
>>> 73, Ed - KL7UW
>>> http://www.kl7uw.com
>>>    "Kits made by KL7UW"
>>> Dubus Mag business:
>>>    dubususa at gmail.com
>>> 
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