[Elecraft] KX3-2M module?

[Don Wilhelm]

Dave,

The drift at a *transceiver* input is *not* multiplied by a transverter.
A transverter is a linear device.  Any change in the input frequency 
results in an equal change in the output frequency.

In other words, if you move your 144 MHz frequency (with the VFO) by 12 
kHz, how much does the 24GHz frequency change?  If you are using a 
transverter, it should also change by 12 kHz.
The same goes with drift at the 144 MHz input.  If the 144 MHz signal 
changes by 10 Hz, the change in the transverter output should also be 10 Hz.

I would expect the greatest contribution to drift at 24 MHz would come 
from drift in the transverter Local Oscillator, not from drift in the 
driving transceiver.

Yes, if you have an intermediate transverter between (say 144 to 1.2 
GHz) between your KX3 and the final transverter to 24 GHz, that 
transverter's LO drift will be added, but that is due to the LO drift in 
that intermediate transverter, not from drift in the KX3.

The drift is *not* multiplied if you are using proper transverters.
If you are using multipliers instead of transverters, I concede, but 
than only CW mode is possible because any modulation on the signal 
(voice modes) would be so corrupted that reception that demodulation 
would be unpredictable and result in garbage unless one knew the exact 
multiplication scheme of the transmitting station.  I don't think anyone 
does that anymore.

Now, if your SHF "transverter" is such that a 12 kHz change in VFO 
frequency at the input results in a much greater change in the output 
frequency, you have something quite different than a transverter.

73,
Don W3FPR

On 4/8/2014 6:18 PM, Dave wrote:
> ----- Original Message ----- From: "Bob" <K2TK at ptd.net>
> To: "Dave" <dave at g0dja.co.uk>; <elecraft at mailman.qth.net>
> Sent: Tuesday, April 08, 2014 9:55 PM
> Subject: Re: [Elecraft] KX3-2M module?
>
>
>> Hi Dave,
>>
>>              I'm not sure if I'm understanding your statement 
>> correctly. I think the big variable is the local oscillator chain in 
>> the transverter not the KX3.  The drift of a few at 144mc is added to 
>> the LO freq not multiplied in any way. Depending on the direction of 
>> the drifts it could be subtractive and improve the stability too.
>
> It is multiplied if you use a transverter to go up to other bands.
>
> Which is what I intended to do in the 1st place.
>
> But. lets go with your "drift of a few at 144mc is added to the LO 
> freq not multiplied in any way" and the addition of  "Depending upon 
> the direction of the drifts it could be subtractive and improve the 
> stability too".  From which I guess that you like to have to follow 
> signals from stations up and down the bands in order to keep track of 
> what they are trying to take you?
>
> Great, I'll resurect my old crystal transmitters, where temperature 
> decided where they drifted off to.  I'm sure that they will be very 
> popular on the modern HF bands these days without proper feedback 
> loops that would keep them within suitable frequency limits...
>
> If not, why would you think that this was acceptable on VHF or UHF bands?
>