[R-390] R-390 Problems - Relay

[Kenneth G. Gordon]

On 16 Aug 2006 at 15:13, Mark Huss wrote:

> Had a similar problem with an R-392, very similar to an R-390.
> Receiver works fine, then suddenly looses sensitivity. Later comes
> back up. Traced it to the Break-In relay contacts being dirty. It
> suprised me a bit as I would think that the contacts would either make
> or not make as long as the contacts did not move. Considered that the
> voltage on the relay coil might be 'iffy', but the relay held to
> 16VDC. Burnished the contacts and everything works now.

One thing we often forget concerning relays is that in order for the 
contacts to STAY in any sort of low-resistance condition, there MUST 
be some current flowing through the circuit that the contacts are 
switching. If that current is below a certain level, the contacts quickly 
oxidize and their closed resistance goes up...sometimes way up.

And this has nothing to do with coil's current or applied voltage.

Ken W7EKB