[1000mp] feedback from rf or speaker in MH31 mike

[Win]

Bill, I had this problem on 40 meters CW.  I ended up putting RF chokes 
(clamp on MFJ type) between the amp and transceiver, the amp and the 
wattmeter, on the mic line, on and on the key line.  This almost completely 
corrected the problem.  Then, strangely enough,  I noted that the problem 
went away completely when my beam, which was not in use, was rotated to the 
SW.  My 40/80 antenna runs near the beam when the beam is at max height. 
Now I just leave the beam at SW when not in use.

Every case is probably a little different, but the feedback is not uncommon 
when the antennas are near the equipment.  I am sure you will get it worked 
out.

Good Luck

W0LZ


----- Original Message ----- 
From: "Bill D" <capers at toast.net>
To: <1000mp at mailman.qth.net>
Sent: Friday, February 09, 2007 10:48 AM
Subject: [1000mp] feedback from rf or speaker in MH31 mike


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> ______________________________________________________________
>
> Hello; I've exhausted my capability to correct the problem of  feedback
> through the mike on 80meters when using more than 50 watts of power. I 
> have
> tried adjustments on mike and can overcome feedback when positioning the
> mike gain at about 9 o'clock or less and alc meter shows little or nothing
> and PO meter is no longer accurate. I tried by passing (disable) tuner and
> still able to transmit with 1:0 or less SWR. Still the effect on the
> microphone and unable to increase power beyond 60 watts. Tried manual 
> tuner
> and no difference. Tunes OK but mike feedback still a problem. Re-grounded
> unit and new balun. All looks OK, but not on 80 meters. Problem does not
> occur on other bands except when using the Ameritron 811H amp with manual
> tuner (3k Roller Inductor) I cannot get the power to the antenna from the
> amplifier and load and plate adjustments must be retuned each time I use
> amplifier.
> Too much text, I apologize. But I've studied help sites on internet for
> 1000mp mk V owners as well as read the manual  many times and still have 
> the
> mike problem on 80 meters with more than 50 or 60 watts . Wonder if anyone
> has had this problem and how it was solved? Thanks much
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