[Drake] relay in T4XC

[Garey Barrell]

Joe -

That works fine.  Be careful not to bend any of the contacts, and DO NOT 
use any sort of abrasive material on the contacts.  Heavy bond paper 
saturated with alcohol, or even a new dollar bill drawn through the 
contacts while applying pressure to keep them together will "clean" the 
contacts if that is all that is needed.  A little DeoxiT LIQUID applied 
to the contacts with the excess blotted off will help preclude repeat 
problems.

If the contacts are pitted or otherwise damaged enough to make you think 
they need filing or other abrasive treatment, save yourself a LOT of 
time and trouble and just replace the relay.  The "correct" replacement 
relay is the P&B (Tyco) R10-E1-Y4-V2.5k, same relay used in the 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 
1/2W resistor in series with the coil, otherwise a drop-in replacement.

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
Atlanta

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



Joseph Trombino Jr wrote:
> I want to clean the contacts in the T/R relay in my T4XC...believe 
> there may be some dust in there causing intermittent contact action.
>
> Looks like the plastic cover will pop off with a bit of prying but 
> wanted to check with the list members to see if this is the way to do 
> it and to see if there is any trick I need to know before attempting 
> this maneuver and possibling breaking the plastic cover..
>
> Many thanks for any info.
>
>                                        73, Joe W2KJ
>
>