K2: Problem With 80m?

[Michael J. Linden]

  I've recently noticed that my K2 produces much less noise on 80m than
on the other bands (40m - 10m) when I have no antenna connected (is this
typical?). And, when I listen to signals on 80m with the antenna
connected, the audio seems somewhat lower than what I get on the other
bands. My AGC is set at 3.8V and appears to be working properly (little
difference in background noise when AGC is switched in and out). 80m
tune-up went well and with a 13.8V supply I'm getting 17.5w on the low
end of 80m and 15.5w on the high end of 80m. The one caveat here is that
I'm using a 10/15/20/40m trap dipole to listen on 80m -- I need to
straighten-out my shack enough that I can compare the K2's 80m receive
sensitivity to that of my Kenwood 930S.
 
  Any input would be appreciated...
 
  Thanks, Michael N9BDF
  K2 #4137
 
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[Ron D'Eau Claire-2]

Attach a shielded dummy load to your K2, turn the AF and RF gains full UP,
Preamp OFF, and the noise in your speaker should be moderate but not really
loud. Of course "loud" depends upon your ambient noise level and other
factors, but you should be able to hear it clearly without being
overwhelmed.

Now cycle through the bands. By ear, the noise level should change very,
very little, if at all, when cycling through all the bands from 160 through
10 meters. Make sure the Preamp is OFF on ALL bands while you cycle. The
firmware will turn it on automatically if you had it on while listening on
other bands.

If one band is a lot weaker than the others, it's time to do some
troubleshooting. I'd start with a careful realignment of the bandpass
filters.

Of course, if you turn the Preamp ON on any band, the noise level will
increase uniformly. I suggested turning it off because it's easier to hear
the change in noise at lower volume levels.

Also you NEED a well-shielded dummy load in case you have a local noise
source that is putting out more racket in some parts of the spectrum and
less in others. You can check that by selecting each band and turning the
ATTN on and off. The noise level should not change. If it does, a local
noise source is leaking into the K2 on that band and confusing your results.



Ron AC7AC



-----Original Message-----
  I've recently noticed that my K2 produces much less noise on 80m than on
the other bands (40m - 10m) when I have no antenna connected (is this
typical?). And, when I listen to signals on 80m with the antenna connected,
the audio seems somewhat lower than what I get on the other bands. My AGC is
set at 3.8V and appears to be working properly (little difference in
background noise when AGC is switched in and out). 80m tune-up went well and
with a 13.8V supply I'm getting 17.5w on the low end of 80m and 15.5w on the
high end of 80m. The one caveat here is that I'm using a 10/15/20/40m trap
dipole to listen on 80m -- I need to straighten-out my shack enough that I
can compare the K2's 80m receive sensitivity to that of my Kenwood 930S.
 
  Any input would be appreciated...
 
  Thanks, Michael N9BDF
  K2 #4137
 


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