{Collins} KWS-1 Drift



Am a little behind the curve answering this; my apologies.

My solution generally took the same approach Bill spoke to but was not as
finished as his.  Indeed, the PTO does heat up during transmit and my
solution was to take a muffin fan and simply put it on top of the open PTO
compartment, blowing down past the PTO and adding a little positive
pressure to the under-chassis.  This approach did not fully stop the drift
but it was a move in the right direction.  I didn't have to re-tune after
each transmission.

As to the audio hum, its probably an issue with that one microphone.
Having said that, When I rebuilt the KWS-1, I re-capped the entire
transmitter and also replaced any out of value resistors paying special
attention to the audio stages.  Used polystyrene media Orange Drops in the
audio section but resisted (is that a pun?) the temptation to fatten a few
of the values but did choose higher voltage ratings.

I may still have the list of caps I replaced if you are interested.

That transmitter REALLY sounded good.

Enjoy your KWS-1 !

Chuck Rippel
WA4HHG


From: Chuck Curran <ccurran@xxxxxxxxx>
> To: "<collins@xxxxxxxxxxxxx>" <collins@xxxxxxxxxxxxx>
> Cc:
> Date: Mon, 24 Nov 2014 16:48:13 -0600
> Subject: {Collins} KWS-1 Drift
> Hello the Group:
> I am a recent Gold Dust Twins operator.  I purchased a functional late
> serial number 75A-4 rebuilt by Howard Mills in 2000.  I also purchased a
> KWS-1 in November of 2013.
>
> The 75A-4 worked fine as received, Geez, I wanted something to fix!
>
> The KWS-1 has provided an expected number of repairs, so I have been
> busy.  Been on the air with it for 2-3 weeks, the only issue has been a
> microphone hum on one of three microphones.  Seems that problem is almost
> resolved.
>
> However, the 75A-4 is rock stable, while the KWS-1 drifts high.  When I
> open the lid and place a cooling fan on the RF deck of the KWS-1,
> transmitter starts drifting low.
>
> I expect I have marginal mica caps in the PTO--any advice or comments on
> this issue?
> Thanks,
>
> Chuck. W9KR
>



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