[Elecraft] K3 Distorted Sound while using AM

[drewko]

My audio will distort and cut out as you describe if it's a very
strong AM signal (nearly full scale on the s-meter) and the volume is
turned up to that extreme. But that is really loud. I usually have the
AF Gain set at 1/4 rotation or less, so don't really consider it a
problem here. I never under any circumstance have to go up as far as
3/4 on the AF Gain (unless the AGC is off and the RF Gain is way down,
in which case there is no distortion). 

FWIW, you can set Config: AF GAIN to "HI" or "LO".

The feel of my AF & RF controls are smooth. They have a very small
side-to-side play but no bad wobble/looseness as you describe.

When I rotate the RF Gain full CCW it is very quiet, just a very faint
noise level can be heard with the AF Gain full CW. I consider it
normal operation.


73,
Drew
AF2Z


On Sat, 05 Dec 2009 20:50:25 -0800 (PST), you wrote:

>
>Hello,
>
>I am having a problem when I go into AM, or AM sync.  Example:  I go to an
>AM Shortwave station.  If I turn the AF gain past approximately 3/4 or
>farther the radio starts to "Stutter, Distort, and finally the audio
>disappears.  I cannot make out what is coming out from my speaker.  The
>audio is completely distorted or gone.  I noticed I could rotate the Af gain
>(Counter Clockwise) and it would go back to less distortion.  I did check
>the external speaker jack and also unplugged it only to find the same
>problem. 
>
>The AF knob feels like it was one of those "old potentiometers" that we are
>all aware of (Get scratchy after use and loose).  From my understanding
>Elecraft used extremely fine pots with a very long life (They do have a bad
>wobble/looseness in them though).
>
>Upon further investigation I found that if I rotated the RF gain control
>from the fully clockwise position (all the way open) to the full counter
>clockwise position (all the way closed) that when you almost get to the end
>of travel the radio audio goes completely dead.  I have tried this multiples
>times and it is very repeatable.
>
>After more investigation I found that if I rotated the "shift" (While in AM
>or Sync AM) control from its standard (Normal) value of 1.50 to 1.55 this
>horrible distortion would disappear?  I am really confused as to what is
>going on here.
>
>This happens while in the "Normal" AM mode as well as the "Sync" AM mode.
>
>I have tried to explain this in away that I hope most people will understand
>my problem (I am not an EE).
>
>Could others please let me know if it is my unit or a wider problem?
>
>I am using 3.59 and the serial number is 283?.  This unit was fully loaded
>and built by Elecraft.
>
>Thanks,
>
>Rick