Re: {Collins} KWS-1 Drift



Hi Chuck,

Not sure how bad the drift is but read below.

Read my Care and Feeding of your KWS-1 article and then see the recent
Signal issue. The problem is typical and due to some not well thought out
thermal paths in the exciter deck. The heat from the PA deck (worse while
transmitting) goes forward over the PTO causing excessive drift even when
fully "up to temperature".. and a long over will heat the PTO up and then it
will cool while you are in listen mode.  If you just put a small fan at the
rear that can be either mounted internally on the existing screws on the
corner of the PA deck, or even outside, and suck some air towards or out of
the rear, that will turn that airflow path around and bring room air in the
front right vent slots towards the PTO... and the drift will major settle
down...  An easy fix usually.

Regards and let us know how it goes.

Regards,

Bill Carns, N7OTQ
Trustee K0CXX
President, Collins Collectors Association
Editor, Signal Magazine
Wimberley, TX
512 618 2762  (Cell)
512 847 7010  (Home)



-----Original Message-----
From: Collins [mailto:collins-bounces+wcarns=austin.rr.com@xxxxxxxxxxxxx] On
Behalf Of Chuck Curran
Sent: Monday, November 24, 2014 4:48 PM
To: <collins@xxxxxxxxxxxxx>
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

Sent from my iPhone
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