[1000mp] audio distortion with amplifier.

[Peter]

----- Original Message ----- 
From: Peter 
To: 1000mp at mailman.qth.net 
Sent: Thursday, October 28, 2004 12:04 PM
Subject: audio distortion with amplifier.


Hi there,

my setup is a FT-1000mp DC (from 1996) with an Ameritron AL-80B.
In a special occasion i'm using my amplifier,perhaps once or twice in year
mostly in a contest.....

I'm still suffering from probably RF feedback in to 1000mp.
When monitoring in SSB the audio is distorted.
it's difficult to explain,it's like sqeezing my audio with ups and downs.
Even in CW there's a raw tone on my signal.

Running my 1000mp barefoot everething is excellent,but with the amplfier
on,it's increasing as the output power increases,the higher ALC level the more 
distorted,even on 200w out it occurs.
I'm not overdriving the amplifier mostly the rig output is around 30-50w
controlled with the ALC on the amp.

I grounded amp and radio seperately,so no ground loops.
I put the 12V-dc cable several times through a large Amidon core.
The ALC and PTT cable,also several times through a Ami. core.
Ferrite clip on beads at the back with my cw key input.
Coax feed used also several ferrite clamps and also a line isolator,
between my coax doesn't helped at all.
Every bead en and core is closest  placed to my chassisrig.

Has somebody any idea or experience through which way the RF
is getting in my rig.(coax,12V-dc cable,ALC-PTT calbe....??).
So in can focus my self  on one item......???

Any suggestions or experencies very mutch welcome.


Kind regards,73's Peter ON7BJ.