Topband: KD9SV-OK1RR relays ???

Tom W8JI w8ji at w8ji.com
Sun Aug 30 20:00:33 EDT 2015


> I'm not sure goosing the pull-in voltage is always a good idea. It may
> shorten the initial closing time a bit, but (depending on the relay)
> it can aggravate contact bounce, doing more harm than good. It also
> stresses the relay.


Done properly, it doesn't hurt a thing. The proper way is to use current 
limiting.

It is safe to run 50 volt supplies on most 12 volt relays, but there is a 
point of diminishing returns on speed. The high initial voltage ramps up the 
magnetic field faster, but it does not cause excessive heat or current. This 
is because the relay starts at near zero mA from inductance.

None of this matters, though. Using a relay on make for protection is a bad 
idea. The de-active state should be used for protection, and the active 
energized state used to allow RX. 



More information about the Topband mailing list