[Johnson] Johnson 500 Power Supply RY302 Relay Needed

[Craig C. Heaton]

Hi Rodger,

I've got a J Desk and KW matchbox. They work well together!! Took the time
to replace the electrolytic in the matchbox before using it with the Desk.

A couple days ago before putting the 500 back on the air. It's my summer
rig, desk is too hot, I tried a RC circuit in the 500 PS/Modulator. It was
across just RY302, no luck. It worked for one or two squeezes of the chicken
choker of the D-104. After which the relays wouldn't pull in. Guessing wrong
values of R & C. So rather than burn up relays that are hard to find or
damage the bias supply, I had this delay relay on the shelf.

Used one of the aux contacts on the Dow-Key ant relay as the switch for the
delay relay. Mounted the delay relay on the back of the R-390A and use it on
the break-in function and to open the RF gain terminals on one of the
terminal strips of the receiver.

Craig



If you cannot get a mechanical replacement you can use a capacitor and
resistor to turn any DC relay into a fast make slow break replacement.
This information is covered in the Desk KW manual (available from BAMA)
and other sources, I had to add an RC network to the external antenna
switch box I built for my Desk KW.  Of course standard AC relays can
also be so modified by the addition of a rectifier diode and possibly a
series resistor before the RC network.

I am hoping to get a chance to fire up my 500 today and I will see if
there is a readily detectable delay in the RY302 break.  The RC network
I put into the Desk KW antenna switch box has about a 1/8 second delay
on break and the delay is clearly audible.

73, Rodger WQ9E