This mic was notorious for RFI.   And as Butch mentioned, the fix is  a 
ground wire  from the mic base to a ground on the radio.  At one time 
the Kenwood lists were loaded with this problem and fix.    Don't see it 
much anymore, maybe everyone with the problem has done the fix, or maybe 
Kenwood  made a change in later production of this mic.

Also, not sure you would really need the pre-amp, but if  you do use it, 
you will need to back down the  mic gain or comp in and out, so as not 
to peg the ALC meter.  You can use the voice readout to set this all up.

73, Steve KW3A


On 12/24/2014 7:11 AM, Butch Bussen wrote:
> One other comment, I had severe rf in my audio problems when I got my 590,
> that radio seems more suceptable than most.  I had to put in a couple of
> those line isolaters and that solved the problem, I can dig up the link if
> anyone wants it.  There were some other fixes with those microphones,
> running a wire down the center of the cord from base of microphone to
> ground on the radio as I recall.  That might have b een the 50, but those
> microphones have been known to have r f i problems as well.  As mentioned
> above, I went from a 2000 with no r f i at all to the 590 and had severe
> r f i which the coax isolators fixed.
> 73
> Butch
> WA0VJR
> Node 3148
> Wallace, ks.
>
>
>