Sam, several years ago I started doing relay switching for automation of band changes etc. At the time I had a 4x811A amp so (optimistically) was aiming for the kilowatt power handling ability (really that amp was lucky to put out 650W).
I had looked at what commercial or published article products use and many of them use PCB mount relays rated for 10-15 Amps. An example would be AC0HB's article in March/April 2014 QEX. He uses Omron G6RN-1-DC12 PCB relays and he was specifying for 1000W power handling ability using these nominal 8A contacts. These relays are very affordable (just $3 or less). I tried these relays and it was a complete disaster for me. Just a few weeks into RTTY contest season, the relays were failing and prying them open they all had extreme discoloration from overheating. It was clear that the high-bands (e.g. 15M) were suffering far more damage than the low bands (e.g. 80M). I think this indicates that the internal structures while they might be sized for 8A at DC or 60Hz, are not sized for the same current at 21MHz. In retrospect, I should have realized that even the tiny PCB pins on them were simply not up to snuff for high duty cycle RTTY contesting. However these relays, I do believe are good for 100W power range. What I ended up using was much beefier relays. I went to Struthers Dunn (now P&B) DPDT T92 relays with paralleled 30A contacts. I got a bigger legal-limit amp and have been COMPLETEY happy with these at legal limit. Over a hundred thousand QSO's through these new relays without a problem. These are the "low impedance" side of my tuner switching. For the high-impedance (ladder line) side of my switching, I use open-frame relays with the contacts pried a little further apart than stock. Example part is the McMaster Carr 7384K14. N6RK outlines the process of widening the contacts in the May 2009 QST Hints and Kinks. Now with any of these Silver contact relays you will have to "clean" them occasionally with either transmit power or (if a RX-only contact) an external voltage source of 12V or more, to blow them clean. W8JI has a good procedure here in his "electrical cleaning" section: https://www.w8ji.com/relay_cleaning_and_life.htm Tim N3QE On Thu, Dec 6, 2018 at 11:48 AM Sam Josuweit <[email protected]> wrote: > Can anyone recommend a good general use relay for antenna switching in the > 800-1000w power range? I know using power relays can be a roll of the dice. > > According to modeling peak voltages should be less than 450V. > > > > Thanks > > Sam(N3XZ) > > > > _________________ > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
