[Elecraft] K2/HF Packer amp incompatibility?

[Don Wilhelm]

  Pat,

Are you using a common power supply on the K2 and the Amp?
If so, try using separate supplies and see what happens.  If the problem 
does not present itself, you can conclude that SSB modulation of the V- 
power supply line is the problem.  See the discussion that appeared on 
this reflector over the last 2 days, subject K3 "RFI in transmitted audio".

73,
Don W3FPR

On 9/13/2010 10:08 PM, Pat Byers wrote:
> A friend recently dropped off his K2 and HF Packer amp for me to
> troubleshoot a problem -- he was getting poor quality SSB reports on
> the air when he ran his K2 through his HF Packer amp. I had built
> both kits and had tested them separately so I was a bit skeptical
> that there was anything wrong. :-D However, when I ran the K2/HF
> Packer combo into a dummy load and monitored the transmitted signal
> with my Icom IC-703 I confirmed that the transmitted signal was
> significantly distorted. Hmmm . . . What's wrong?
>
> Just to narrow down the problem I tried the amp with my IC-703 and
> the transmitted signal sounded great with no discernible distortion.
> The only discernable difference with the amp switched in or out was
> the signal strength. I then monitored the K2 barefoot and it sounded
> fine as well. As a further check I had a friend bring over his K2
> which had been aligned by Elecraft. His radio sounded fine barefoot
> but when it was used with the amp there was significant distortion in
> the monitored signal. Just in case of an impedance mismatch between
> the K2s and the amp I ran the experiments with both K2s using the
> built-in ATUs and with the ATUs out of the signal path. The results
> were distorted audio in all cases.
>