Good news Tom,

Just like being a drunk or drug addict, admitting the problem is the 
first step to getting  it solved.   In your case, finding the source of 
the trouble out of the    multitude of possibilities is a big step.


If you have the same mic as i have, it has a cord about 8 ft. long. 
Try winding up the excess into a coil, along with the ferrite.   I 
replaced my cable years ago with a shorter  one that ends in a 1/8 plug, 
so I can switch between headset and Gold Line very fast.

Just for the heck of it, you may want to try a ground wire between mic 
and radio and see what happens.  Either a jumper with clips, or loosen 
the nut at the toggle switch and slip a wire under.

Now that I think about it, i remember Heil's web site explaining the 
need to  ground these things better, and to  jumper one of the pins on 
the 8 pin connector to the shell of the connector.  I think the mic has 
a floating ground that needs to be brought to chassis ground.



Maybe you will have a happy ending to "How I spent My Spring Vacation".

73, Steve KW3A


On 3/10/2011 8:35 AM, tom behler wrote:
> Hi, all.
>
> I think I have finally gotten to the bottom of my RFI problem on 20 meters
> when using the Alpha Delta DXCC antenna.
>
> Now, all I have to do is figure out how to fix it, and how to replace what
> little hair I still have that has been pulled out in the process.
>
> My problem is with the cable for my Heil Gold Line mic!  Thanks to Kevin
> (K7RX) for giving me the clue.
>
> I used headphones to monitor my transmit audio, first with the stock mic
> that came with the TS480.  Crystal clear audio on both 100 watts, and 600
> watts using the amp.  Then, switched back to the Heil.  Crystal clear audio
> on 100 watts, but terribly distorted audio using 600 watts and the amp.
> Tried putting an RF choke around the Heil mic cable, which reduced the
> RF-generated audio distortion considerably but not completely.
>
> Just for grins, I tried the Heil set-up on 40 meters with both low and high
> power, and had crystal clear audio both times.
>
> So, obviously, that mic cable is doing something to me on 20 meters.
>
> Will write to the folks at Heil for their suggestions, and would appreciate
> any thoughts any of you have as well.
>
> I'm relieved, but now have to figure out what to do to correct the
> situation, if I'm going to use my Heil gold line mic on 20 meters with the
> Alpha Delta DXCC.
>
> 73 from Tom Behler: KB8TYJ
>