[Hallicrafters] WA0ZCW Needs Assistance - Please Read

[Roger(K8RI)]

I'd also bet the voltage is changing, but it may be due to a leaky ceramic
coupling cap(s) related to the transmit side.  The darn things could be most
any where, but I had the ones go out in the driver circuit on the HT-44.
That had some rather obvious side effects such as not being able to keep the
idle current stable. The coupling cap from the plate of the driver to the
grids of the finals as well as the bypass caps were bad.  Leakage changed
like crazy with heat.

I also ran into some bad ones in the SX-117 and "as I recall" they were in
the first RF stage.

Hallicrafters apparently ran into a bad batch of those little disk ceramics.
I think they were all 0.01 ufd, but many have been 0.001. I don't remember,
but all the ones that did go bad were of the same value.

Roger Halstead (K8RI, EN73 & ARRL Life Member)
N833R, World's Oldest Debonair? (S# CD-2)
www.rogerhalstead.com


> Yes, the same thing happens to the Collins KWM-2.
>
> Check the voltage of the VFO with a digital meter for best accuracy,
> then key the transmitter and check the voltage again.
> I'll bet the voltage changes. There is probably a regulator circuit
> associated with the vfo and that's probably where you will find the
> trouble. Can't tell you exactly where as I am unfamiliar with the
> SR-2000.
>
> Regards
>
> Dave Harmon
> NSRCA 586
> K6XYZ at comcast.net
> Torrance, Ca.
>
> -----Original Message-----
> From: hallicrafters-admin at mailman.qth.net
> [mailto:hallicrafters-admin at mailman.qth.net] On Behalf Of Duane Fischer,
> W8DBF
> Sent: Saturday, October 18, 2003 2:25 PM
> To: hallicrafters at mailman.qth.net
> Subject: [Hallicrafters] WA0ZCW Needs Assistance - Please Read
>
>
>
> Mike, WA0ZCW has a SR-2000. After it has warmed up for a hour, maybe
> more, it
> will change frequency by about 100 cycles when he transmits. He has done
> the
> usual tube checks, cleaned pots and so forth. Does anyone have a
> suggestion as
> to the possible cause and cure for this problem?
>
> Thank you on behalf of Mike -
>
> Duane W8DBF
>
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