[Elecraft] Re: Elecraft K2 Temperature-Compensated PLL Reference Upgrade

[David A. Belsley]

Thanks for the info, Wayne.  I'll order mine later today.

best wishes,

dave belsley, w1euy

--On Saturday, April 26, 2003 12:30 AM -0700 Wayne Burdick 
<n6kr@elecraft.com> wrote:

> "David A. Belsley" wrote:
>
>> One further point, if I may.  Suppose one's K2
>> does indeed have low TC.  Will the addition of the thermistor mod now
>> cause over compensation, perhaps even producing negative temperature
>> compensation (in the opposite direction)?
>
>
> If the TC seems to be low, it could simply be because the K2 is being
> used in a relatively temperature-stable environment. Or the PLL TC and
> BFO TC could be cancelling each other out only on certain bands. To check
> for this, you could test drift on 17 and 10 m, where the VCO is in about
> the same range but the BFO is subtracted/added, respectively. You may
> find that drift is much worse on one than on the other.
>
> But even if the TC really *is* low, the PLL upgrade mod can only make it
> better. The upgrade kit includes a new highly stable reference crystal in
> addition to the thermistor compensation components. Every K2 tested
> during field-testing of the PLL upgrade showed a factor of about 5 to 10
> improvement.
>
> Given the possible PLL/BFO TC cancellation scenario, you should certainly
> make the BFO modification at the same time to eliminate the BFO as a
> variable (unless your K2 is s/n 3000 and up; these already have the new
> BFO inductor).
>
> One other feature of the thermistor compensation circuit is that the
> amount of compensation can be fine-tuned (if you insist) by changing just
> one resistor value. Details on how to test the residual drift and tweak
> this resistor value are included. But such tweaking IS NOT REQUIRED or
> recommended. Some experimentally-inclined builders will want to do it
> anyway, which is why we include the info.
>
> 73,
> Wayne
> N6KR



----------------------------------
David A. Belsley
Professor of Economics