[Icom] SM-20 DESK MIC PROBLEMS-756 PRO

Sat, 11 Jan 2003 18:46:32 -0000

Check for an uninterrupted flow of power to the mic, or some component that
is slowly bleeding power away.  If the voltage to the mic slowly decays, it
will give that symptom.

Mike.  El Paso, TX.

> -----Original Message-----
> From: [email protected] [mailto:[email protected]]On
> Behalf Of David S McCallum
> Sent: Saturday, January 11, 2003 6:36 PM
> To: [email protected]
> Subject: [Icom] SM-20 DESK MIC PROBLEMS-756 PRO
>
>
> Have developed a problem with my SM-20 Desk Mic. At first it starts to
> work fine, good alc indication and shows rf power output and the scope
> shows output. As I talk I noticed the ALC starts to bleed off
> and stops
> at zero, my scope on the radio still show an output indication. If I
> unkey and rekey it shows good ALC but then bleeds off again
> then I start
> getting reports of breaking up, sounds of RF and when I'm
> speaking into
> mic the reports say it sound like I am crunching some paper
> in front of
> the mic.
>
> I took the plug apart that goes to the radio all connections
> and solder
> look ok,  jiggled all the cords on the mic and thought I had
> it isolated
> to a bad wire but when I took it all apart everything looks ok and
> continuity checks on the cables all looked good. I can also hear the
> break up problem on the radio monitor system but not the crunchy paper
> sound.
> This just started a week ago and my hand mic that comes with
> the PRO is
> working ok.....Any ideas gang and does the mic element cover
> unscrew so I
> can check there? Thanks and hope some one can help, 73 Mac
>
>
> David S. McCallum/USAF Retired/ Chief Mac/w7sac/4
> ----
> Your Moderator: Dick Flanagan W6OLD, [email protected]
> Icom Users Net: Sundays, 1700Z, 14.315 MHz
> Icom FAQ: http://www.qsl.net/icom/
>