Re: {Collins} KWM-2 grid drive SOLVED



Problem solved. I replaced the Mic Gain Pot/Switch with a new one from
Surplus Sales of Nebraska. The needle on the meter is now stable, and it is
much easier to adjust drive grid gain and to do the RF circuit alignment.
Checking the old pot with an FET ohmmeter didn't prove intermittent
problems, but gently pushing or pulling the shaft certainly did. While I was
at it, I also replaced the R15 carrier balance pot which previously had been
responsible for erratic drive.
Thanks to all the ones who responded.
Peter OZ8CTH 

-----Oprindelig meddelelse-----
Fra: Bill Carns [mailto:wcarns@xxxxxxxxxxxxx] 
Sendt: 14. september 2017 22:56
Til: 'Peter Ravn'
Cc: COLLINS@xxxxxxxxxxxxx
Emne: RE: {Collins} KWM-2 grid drive

It is not normal Peter and I suspect that it indicates some kind of
instability like a parasitic .  It could also be an intermittent connection.
Slight tapping on the case with the butt of a screwdriver while observing
the needle will give you some leads as to whether it is mechanical in nature
or if it is electrical.  If you have access to a spectrum analyzer, it is
time to press it into service.  If not, then a really good very high
frequency scope may show the problem.

Bill

-----Original Message-----
From: Collins [mailto:collins-bounces+wcarns=austin.rr.com@xxxxxxxxxxxxx] On
Behalf Of Peter Ravn via Collins
Sent: Thursday, September 14, 2017 9:39 AM
To: collins@xxxxxxxxxxxxx
Subject: {Collins} KWM-2 grid drive

When in tune I peak the grid drive on my winged KWM-2, the needle on the
meter is never 100 percent stable. It will fluctuate app. 5mA no matter
position on the scale. Is that normal for a KWM-2? If not, what does it
indicate?

Thanks.

Peter OZ8CTH

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