Yes, vacuum relays have a finite life. And reversing the polarity did not work
for me, although It may work with different makes of vacuum relay.
If it is the vacuum relay then it is indeed hard to locate a replacement - it
is a 12v device and all the surplus ones I have seen are 24v. I have been
through this once before when TT could supply them at a mere $120.
If (when) it happens again I will try a different and very much less expensive
solution before reaching for a credit card.
My solution (?) depends on the fact that the vacuum relay is not hot switched
... it is in a 50 ohm line and so the RF voltage is not particularly high.
Any replacement needs to be (a) fast enough (b) abls to carry a lot of
current (c) have reasonably good isolation between coil and contacts.
There is a 12v FINDER relay, part # 4152.9.012.0000, which is claimed to hot
switch up to 8 amps at 250 volts AC. The coil/contact breakdown voltage is
5000. The operating speed is not quite as fast as a vacuum relay, but it is
pretty quick and at well under $10 a time it looks worth a shot.
OK, its a fairly small potted gizmo and it will need to be hard wired into the
Herc, but what the heck. If I have to use slow QSK thats better than nothing.
Anyway, how do the really BIG amplifiers solve this problem ?? I'm sure they
do not all use expensive vacuum relays, or do they ?
Happy hacking in 2004
73 John G3JAG (donning flak jacket before the flames arrive)
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