From: Garey Barrell 
Subject: Re: [drakelist] T4XC relay source?


Hi David -

Potter & Brumfield R10-E1Y4-V2.5K is the standard relay in all the T(R)-4 (any) 
transmitters.

The Varley relay is a 15K coil, which meant very fine wire.  There was a fairly 
high failure rate caused by the wire breaking, possibly because of the heating 
and cooling cycles of the transmitter.

The only change necessary to use the 2.5K ohm relay above is to add a 1.5K, 1/2W 
resistor in series with the coil.

They're available from both Digi-Key and Mouser for about $15.  They're also 
available from Newark, and probably their Farnell division in EU.

73, Garey - K4OAH
Atlanta

David Austin wrote:

> Hi everyone,
>  
> Trying to fix my T4XC last night, discovered that the problem is an open 
> circuit solenoid on the plug-in relay (K1). The relay is a Varley VP4 
> CAB/120. Just wondered if anyone has needed to replace this before and 
> if so where they might be obtained at reasonable price? I have searched 
> the web to no avail (quite a few VP4, but not this specification). Have 
> contacted manufacturers here in the UK (now owned by Clifford and Snell) 
> who tell me that all relays are made to order in batches, so think their 
> quote is going to be quite expensive. The closest I have found is a VP4 
> CAB/26 (26 volt solenoid as opposed to 120 volt), which will presumably 
> not be suitable even with circuit mod?
>  
> Also, is there a liklehood that a fault in the vox control tube (6EV7) 
> used to switch this relay could have caused the burnout, or is this very 
> unlikely? Can plate resistance of a tube go low, causing excess current 
> draw? Don't want to replace the relay only to blow it again!
>  
> David
> G4GTP

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