[Elecraft] troubleshooting # 4115

[Don Wilhelm]

Bud,

With those symptoms, I could be lead to believe that something is modulating
either the BFO or the VFO in your K2.  The most likely cause is a bad or
missing solder connection, and I would be particularly suspicious of bypass
capacitors.

The best way to find out which oscillator may be causing the problem would
be by observing the wave envelope at TP1 or TP2.  If you do not have a
'scope available, try connecting a short (one or two feet long should do)
antenna to TP1 and TP2 alternately while listening to the oscillator signal
with another receiver - it should sound like a good clean CW note if all is
well.

Once you determine the area causing the problem, troubleshooting it should
be easier, but attempting to find the troublesome area by trial and error
can be a long and frustrating process.

73,
Don W3FPR

----- Original Message ----- 
> I have the internal battery option, so I buttoned up the K2 and took it
> out on the deck, a good ten feet from any AC source.  The symptoms
> didn't change.  I sure was hoping they would.
>
> The symptoms are slightly different on different bands.  On 40 where
> I've spent the most time, the signal is dirty on key down but clean if
> I go into tune, although it does seem to chirp just for a tiny fraction
> of a second as it comes up in tune the first time after a band change.
> Other bands are similar except they seem to take longer to get stable
> the first time after a band change, some as much as 2 or 3 seconds.
> All are very dirty on key down.  That led me to spend a long time
> looking around the BPF and LPF on the rf board.
>
> Receive audio distorts on all bands when I turn on Spot.  That led me to
> U8 and U10 on the control board, thinking there might be some
> interaction between sidetone and ALC.  Now I'm wondering if I should be
> looking around the synthesizer.
>
> -- 
> Bud Rogers <budr@netride.net>
> KD5SZ EM05vb K2 #4115