K3 on-channel strong signal overload?

Posted by orbarrett on May 04, 2009; 4:39am
URL: http://elecraft.85.s1.nabble.com/K3-on-channel-strong-signal-overload-tp2785612.html

Hello all,

I just finished operating my K3 from my friend's driveway using a portable dipole on 60M, and wanted to inquire about some incoming signal overload that cropped up.  I was joined while ragchewing with some friends on 5371.5 by two other friends locally, one operating HF mobile from the same driveway and another operating from a base rig in the shack (using a backyard dipole antenna).  When either of these two friends transmitted on the same channel (at 100W), I observed severe signal breakup in the K3 receive audio.

To investigate further, I switched the portable antenna from the K3 to my friend's FT-817 on the same operating table, and no audio breakup was observed under the same conditions.  Returning the antenna to the K3, I then got rid of most of the signal breakup by turning on the input attenuator and turning down the RF gain to near minimum.

Is it possible that the extremely strong on-channel signal in this case is exceeding the ability of the K3's hardware AGC to protect the A/D converter input?  Thanks for any suggestions on this, including anything I may have overlooked.  AGC was enabled and both the NB and NR were switched off.

I should mention that these conditions of operating portable (with several hams close-in on the same channel) are very demanding, but happen occasionally in certain situations such as for HF Pack operating.
I'm also using the rig in HF mobile service, and enjoy it very much.

I appreciate any help in advance,
Oliver Barrett  KB6BA