[Collins] Early KWS-1

[Dr. Gerald N. Johnson]

My 4th edition manual is missing the power supply schematic. It shows no
overload reset switch in the pictures or overload relay in the section
on how it works. There is a K502 in the parts list, says not used. Same
as the 7th edition that is available on line both at CCA and mods.dk.

The on line article, "KWS-1 The Care and Feeding and Other
Trivia-Small.pdf" Says the overload relay and the louvered front door
disappeared by the time volume floor production began.

There is nothing in the service bulletins about an overload relay.

It may be necessary to trace the schematic of the primary and secondary 
wiring to that overload relay, which I presume is K502 and should have 
that number on the chassis along side the relay. I start with a large 
sheet of white paper and keep my pencil sharpened. With the large sheet 
of paper I don't have to be so organized as I chase circuits.

I'd expect the overload relay to be a latching relay in either the PA 
plate or screen circuit probably sampling the high voltage current in 
the PA plate transformer centertap wire with possibly a potentiometer 
for setting the sensitivity. It could be mechanical latching with two 
coils or electrical latching with one coil. It would expect it to break 
power to the PA plate transformer primary contactor/relay. E.g. to be in 
series with the front panel plate switch and the interlock switches.

If mechanical latching (two coils) the reset switch would be a momentary 
toggle to apply power to the reset coil. These were not rare parts in 
those days.

If electrical latching there would be another relay contact applying 
power to the main coil or a second coil on the same core to hold the 
relay on opening the same plate control circuit and the reset switch 
would be normally closed to open that latch circuit when opened.

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

On 1/9/2013 3:40 PM, gman003 at hawaii.rr.com wrote:
> Hi all. I am helping a fellow ham who recently acquired an early
> KWS-1 with the power reset toggle switch. We have searched the
> internet but am unable to find the early manual. There seems to be
> quite a difference in the early and late models of the power
> pedestal. I would gladly pay for a copy and shipping if anyone has
> the manual. Thank you. Gareth KH6RH.
> ______________________________________________________________
>