[Elecraft] Re: K2 SSB problems

[Ron D'Eau Claire]

What I was referring to specifically, was discussed around six to eight
weeks 
ago and generally subscribed under the subject "Muddy SSB."  That, I
believe, 
referred to RX and XMIT, although mostly the latter.  From the
responses, I 
gather that poor
XTAL's were primarily to blame, and then mostly on a sporadic basis or
in 
early release K2's.  
Gary "Lyam" Freeman
======================================

I was one of the ones who was a part of the discussion (and getting a
fix) for the "muddy SSB" problem. It does NOT show up in receive, as far
as I have seen. It is only really apparent in transmit. 

There is quite a separate issue with SSB receive quality that involves
the filter at the output of the i-f amplifier: the 2nd Xfil. This is a
simple crystal filter used to "clean up" the signal at the i-f amplifier
output in receive. It is NOT used in transmit. This filter has a
distinct slope to its bandpass that is apparent in the comparatively
wide bandpass used for SSB. It causes the SSB reception on some bands to
sound bassy, and on other bands it sounds "tinny" or high-pitched. The
change from bassy to tinny is caused by the mixing scheme used in the K2
on the various bands. There is a "fix" for that problem on the Elecraft
web site under "Builders Resources". Look for the "2nd xfil Filter
Flattening Mod".  Note the mod has NO EFFECT on the transmitted SSB
signal, only the received signal.

You are right that the problem with "muddy" transmit audio quality was
apparently limited to a few early K2's, according to correspondence I've
had with Wayne and Eric. My K2 is over 2 years old. I used my SSB module
for digital (PSK 31, etc.) communications and didn't really check it out
on all bands for voice transmission until recently. When I did, I
discovered that it was impossible to set the BFO for good audio quality
on one sideband. 

As turned out I had a defective crystal(s) in the SSB module. Changing
all the crystals fixed the problem. 

If you have poor transmit audio quality, I would suggest dropping a line
to support@electraft.com. I guarantee you they will jump right on it. 

There's only one thing that I've seen that works better than an Elecraft
rig. That's Elecraft customer support. 

Ron AC7AC
K2 # 1289