[Elecraft] K2 Temp. compensated PLL mod

[Phil Wheeler]

Eric Swartz WA6HHQ - Elecraft wrote:

> Yes the BFO toroid mod does alter the relationship between the DAC 
> numbers and the actual BFO frequency. The inductor the toroid replaces 
> impacts what frequency the BFO oscillates at. A slightly different 
> value inductor (the toroid) will change the natural frequency of the 
> oscillator, requiring a different varactor voltage (controlled by the 
> DAC voltage) to reach the same operating frequency.
>
> Always write down your filter BFO frequencies, not the DAC numbers.
>
> Also don't forget that the BF1t frequency also sets the SSB transmit 
> audio range and that a very small change in this parameter (+/-100 Hz) 
> can make a big difference in the quality of your transmitted SSB 
> audio. (There is a different BF1t setting for USB, LSB and Data modes.) 



Welcome back, Eric.

I did the 14 xtal mod, the BFO mod and the PLL stability (thermistor) 
mod.  I did record the BFO freqs before I started.  But when done, I 
used the BFO settings recommended for the 3.7 (written on the envelope) 
xtals in the SSB module instructions.

Was I correct in assuming that with new xtals this would be the best 
course vs. going back to the old settings?

73, Phil

p.s. -- Will do a Spectrogram adjustment as soon as I build the noise 
generator kit.