Tom, What would be a better choice for a stack match?
I'm quite sure that in the heat of a contest these things have been hot switched on rare occasion with 1500w. There was one time when I intentionally hot switched one of them with 100w because I thought the receive signal was down 10dB or so. Problem went away. Anyway I've been using them for about 6 years or so and only had one that failed after a big lightening strike. Stan, K5GO Sent from my iPad On Oct 10, 2014, at 7:29 AM, Tom W8JI <[email protected]> wrote: >> I have built four or five "stack matches" using these relays and have been >> quite pleased with them. >> >> http://www.mouser.com/ProductDetail/TE-Connectivity/T92S11D22-12/?qs=%2fha2pyFadujQKxyiQ9QJsU9gOmzykpctnwthD3xoZjoJPHbNrun4hw%3d%3d >> >> 73...Stan, K5GO > > If you look at the contact material, it is the wrong material type for our > applications. Those relays are hot switch relays for high current > applications with Silver Cadmium Oxide. From an engineering bulletin on > selecting relay contact materials: > > Silver Cadmium Oxide > > Silver cadmium oxide contacts have long been used for switching loads > > that produce a high energy arc. Silver cadmium oxide contacts are less > > electrically conductive than fine silver contacts, but have superior > > resistance to material transfer and material loss due to arcing. They do > > exhibit greater interface resistance between mated contacts, and also a > > slightly greater contact assembly heat rise. The minimum arc voltagerating > > of silver cadmium oxide is 10 volts and, like fine silver contacts, the silver > > in this alloy will oxidize and sulfidate. Therefore, an arc is necessary to > > keep these contacts clean. > > > This doesn't mean they won't work and will go up in smoke. It does mean they > are subject to contact sulfidation which causes intermittent receive. They > have silver, a hard base material, and large contact area that does not wipe > well. They also are the type of relay that is subject to contact derating > from skin effect because of constant resistivity. > > > 73 Tom > _________________ Topband Reflector Archives - http://www.contesting.com/_topband
