[Collins] KWS-1 RX mute issues.

[Bill Riches]

I have repaired relays in the past using the mylar from paper protectors,
the oldest being in a KWM-2 that has been in daily use for about 10 years
after the repair with no problems, yet.  In the 7 or so KWS-1 transmitters
that I have restored, five of them had stock antenna relays but not enough
external contacts to use for receiver muting.  If you were to use an antenna
relay with extra contacts you must disconnect the hot keyed rx line that has
350 volts on it and put heat shrink on the removed wire.  You don't want
someone else to play with the mute line and get zapped.  You could die. 

Sorry to be so windy with my comments and findings but us folk that have
worked on our ancient gear have to remember that the newbies of our group
appreciate more detailed info as we all did when we were just learning.

This should end this thread!

73,

Bill, WA2DVU (Technical advisor and janitor for dB Electronics!)
Cape May, NJ 

Subject: Re: [Collins] KWS-1 RX mute issues.

A workable solution, though the plastic of the paper protector probably will
wear through. A bit of mylar like from a drafting original would wear
better. Or thin fiberglass circuit board. Another work around might work if
the antenna relay has auxiliary contacts, they can do the receiver muting.

73, Jerry, K0CQ, Technical Adviser to the Collins Radio Association.

On 6/1/2014 7:07 AM, Bill Riches wrote:
>
>
> Noticed that my KWS-1/75a4 rig was not muting at times. Found a 
> problem in
> K101 and here is how I fixed it.
>
>
>
> Pin 9 of K101 has 350 V that contacts pin 8 when keyed.  Pin 8 of 
> relay moves pin 6 of relay to open rx mute circuit.  There is a black 
> insulator at moves pin 6 from pin 8.  This insulator breaks down and 
> puts the hv on the mute line.  Good news! You do not have to replace
relay.
>
>
>
> I cut a 1/8 x 1 inch of plastic sheet from a page protector sheet and 
> put it between the insulator and the actuating relay leaf.  A drop of 
> GC service cement at the base of the leaf seems to hold it in place.
>
>
>
> Working on the rig with the right side down on the bench puts 
> everything in sight.  At least these contacts were accessable.
>
>
>
> To check your rig: Disconnect mute lines from rx,  check for voltage 
> between both mute lines from tx with tx keyed (hv on), and if you see 
> ANY voltage you have a problem.
>
>
>
> 73,
>
>
>
> Bill, WA2DVU
>
> Cape May
>
>
>
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