Pete Smith wrote:
> Another trick to consider is arranging the relays so that there are two
> sets of open contacts between ports.
>
> BTW, it is quite amazing how little relay capacity is really required
> for a legal limit antenna switchbox - Top Ten, for example, uses a NAiS
> relay that costs about $2 a pop. I have tried to break these running
> really high SWRs at 1200 watts - without success.
>
That's because relays are typically rated/designed for their "making" or
"breaking" performance, and as a general rule, we don't "hot switch" the
relay...
A pretty small relay can be rated at 30 Amps (look at the little relays
in cars) and 30A, even at 3:1 ISWR, is a lot of power (1200W is 5Amps
into a 50 ohm load). And, once the contacts are open, a fairly small
gap will stand off a kilovolt (about 14 mil, 0.4mm). 1200W is 250V or so.
(and, to give the Top Ten folks credit, they probably did try multiple
relay models.. not all relays with a given rating work at RF)
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