Re: K3EXREF and Trimble Thunderbolts

Posted by Don Wilhelm-4 on Apr 05, 2011; 11:47pm
URL: http://elecraft.85.s1.nabble.com/K3EXREF-and-Trimble-Thunderbolts-tp6242158p6244197.html

  Julian,

Please explain why you think any vfo tuning "steps" are related to a
frequency shift induced from the audio input to the K3.  I believe this
is mixing two entirely separate parameters.

I have not actually operated WSPR, but it cannot be that difficult (nor
that precise in practice).  I believe one would use DATA A sub-mode for
WSPR work.

The VFO places the waterfall within 1 Hz of the desired fequency with
the external reference (actually that could be within 50 Hz - same
argument).  Now the software applying the audio to the K3 has to shift
1.5 Hz (or 170 Hz for that matter),  As long as the K3 can tune the
desired frequency to be in the passband, the software and audio input to
the K3 will take care of the audio shift.  The only requirement is that
the K3 remain frequency stable once the frequency is selected - the rest
is done in the computer application software.

73,
Don W3FPR

On 4/5/2011 5:53 PM, Julian, G4ILO wrote:

> Thanks to Leigh for his detailed explanation. Also to you, Rich, for
> explaining how the frequency standard is applied to the K3.
>
> I still have a couple of questions.
>
> If, as I believe is the case, the K3 REF CAL has fairly large discrete
> steps, is there any benefit in using a reference oscillator that is many
> times more accurate than that? All one is looking for is something that will
> keep the K3 as accurate as it can be without the need to perform regular
> manual checks. A standard that has extra precision is not going to make the
> K3 any more accurate because the reference oscillator is being controlled
> using discrete steps.
>
> Has anyone tested the effect of these small stepwise adjustments of
> frequency on the WSPR mode, in which the data is transmitted using a
> frequency shift of about 1.5Hz?
>
> Julian, G4ILO
>
>
> Rich Heineck wrote:
>> The K3EXREF uses the 10 MHz standard as it's time base to measure the K3's
>> TCXO and passes
>> an error value to the K3's MCU every few seconds.  No TCXO frequency
>> control takes place,
>> thus no increase in phase noise.  Frequency compensation is done in
>> software by
>> automatically updating the REF CAL function.  A relatively simple
>> mechanism but effective :)
>>
>> For my installation, I'm using a Thunderbolt, an $11 active antenna from
>> Digi-Key, and a
>> 30' run of RG-6, which works nicely with the F connector on the Tbolt.
>>
>>
>
> -----
> Julian, G4ILO. K2 #392  K3 #222.
> * G4ILO's Shack - http://www.g4ilo.com
> * KComm - http://www.g4ilo.com/kcomm.html
> * KTune - http://www.g4ilo.com/ktune.html
>
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/K3EXREF-and-Trimble-Thunderbolts-tp6242158p6243940.html
> Sent from the Elecraft mailing list archive at Nabble.com.
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html