[Elecraft] Elecraft K2/100 in RTTY and PSK31 Modes

[Vic Rosenthal]

Julian, G4ILO wrote:

> The main issue is the limited VFO and BFO frequency resolution, which leads 
> to a slight audio shift when you change selectivity. 

I have been able to completely eliminate this shift.  What I do is first 
do CAL FIL for the appropriate bandwidths, for example 1.6, 0.8, 0.4, 
and 0.2 KHz, using Spectrogram.  Then I tune in a steady signal (the 7 
MHz birdie) and go through the four selectivity positions, noting the 
change (if any) in the location of the pip on the Spectrogram display. 
Suppose I find that the frequency in the 0.8 and 0.4 positions is 10 Hz 
higher than the others.  In that case, I change the bandwidth slightly 
(let's say to 0.78 and 0.42), and move the BFO frequency one 'click' to 
compensate.  When the new filter parameters are saved, more often than 
not the VCO offset is calculated so that the pip comes out on target. 
You may have to try several combinations of bandwidth and BFO position, 
but it has always been possible for me to have it come out right.

Before bothering to do this, however, it is imperative to do the BFO 
drift mod (included in K2's from serial no. 3000).  Otherwise, the 
alignment will drift.

> The other apparent issue with the K2/100 is drift, due to the higher 
> temperatures if the PA is mounted internally. There's a mod to compensate 
> for this, but I don't know if it stops it sufficiently to be satisfactory 
> for data use. 

I don't either, being a CW operator, but I will say that it provides a 
BIG reduction in the amount of drift.  This mod is applicable to K2's 
earlier than #3446.  I recommend this mod for all K2/100's, regardless 
of your favorite mode.  I've also added an auxilliary fan -- a 3" (about 
7.6 cm) square 12v DC fan which I stuck on the right side of the K2/100 
  heat sink with double-sided tape just for the heck of it.

Vic K2VCO