[Drake] TR4C Antenna Relay

[Garey Barrell]

The "correct" replacement relay is the P&B (Tyco) R10-E1-Y4-V2.5k, same
relay used in the "late" T-4XC and TR-4C, which IS available from Mouser
and Digikey among others.   About $15.

If your old relay is a Varley with a 15k coil, you need to add a 1.5k 1W
resistor in series with the coil, otherwise a drop-in replacement.  Look
at the socket for V10, the 6FQ7 (or 6EV7).  If there is a 1.5k, 1W
resistor connected between Pin 6 and Pin 9, just plug in the new relay.
If there is NO resistor, remove the wire connected to Pin 6 and move it
to Pin 9, add a 1.5k, 1W resistor between Pin 6 and Pin 9, and plug in
the new relay.

The 15k ohm coil relays were failure prone, primarily because of the
very fine wire needed.  The bobbin would swell,  especially in humid
conditions, stressing and breaking the wire.  This is why T-4XC's that
have been stored in the garage for a while often have a bad relay!  The
2.5k ohm coil of course uses considerably larger wire.

73, Garey - K4OAH
Glen Allen, VA

Drake 2-B, 4-B & C-Line Service Supplement CDs
<www.k4oah.com>



Bill Campbell wrote:
> Does anyone know where I can get a replacement relay for my TR4C as mine will no longer mute the receiver on transmit.   Thanks!
>
> Bill - WD4HEN
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