[AMRadio] Relay Rating


JAMES HANLON knjhanlon at msn.com
Tue Dec 15 12:54:29 EST 2009


John,

I can't beat Bernie's reply from experience, but I will add that 300 watts of carrier would produce 2.45 amps of current into a 50 ohm load and 2.04 amps into a 72 ohm load, so you won't be anywhere near "overloading" the 10 amp rated contacts.  

Personally I use a mercury-wetted relay to switch my tuned-to-50-ohm antenna load between my transmitter and receiver.  The transmitter can deliver as much as 600 watts CW from my SB-200, which corresponds to 3.46 amps into 50 ohms.  My relay is a Western Electric 276 rated for 5 amps "DC."  I do not hot switch it, at least intentionally, since I have a timed QSK system.  It holds up just fine in this service.  

Jim Hanlon, W8KGI


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