Hi Jim
I hear RTTY contest and I have to ask the obvious, are you using a heat sink
or just the panel of the enclosure?? Are you using active or passive
cooling in the enclosure?? I would also ask if both sides of the SSR is
protected by MOV's per Crydom's recommendations??
Mouser sells the book, "Solid-State Relay Handbook" from the Crydom company,
less than $20. It has very interesting information and is recommended
reading for any application of a SSR
I've been using these in all my amps for over 10 years as well have a few
commercial manufacturers. I can't speak for them but I have no failures. I
have deliberately shorted my HV supplies several times testing the IP
overload operation of the triode board, again no problems. I know of no
other relay fast enough to make the IP overcurrent protection comply with
Eimac's application bulletin #17. The only problem I have ever had with the
SSR's is not having the minimum load on the relay with the cap input power
supplies during stand-by. The relay will turn off and on at 60hz, (hum). I
usually add some shunt resistance to the primary of the transformer and all
is well.
vry 73, Paul
PAUL HEWITT
WD7S PRODUCTIONS
QRO HOMEBREW COMPONENTS
http://home.earthlink.net/~wd7s
----- Original Message -----
From: "Jim W7RY" <w7ry@centurytel.net>
To: "amps" <amps@contesting.com>
Sent: Sunday, February 09, 2014 7:13 PM
Subject: [Amps] Solid State Relays Again
I just had a solid state relay in my 8877 power supply short during the
RTTY contest this weekend.
I use 2 relays, one to short out the step start resistor, and the other
one for the other leg of the plate transformer. Both are controlleed by
the WD7S triode board.
The one that shorted is was NOT the step start resistor shorting relay.
They are both Crydom D2440. They have been around a while because the
defective one has a date code of 9425.
Just trying to do some research and thinking of switching to mechanical
relays.
I looked at the archives and read a debate between Ian and Paul about this
exact subject. Any new thoughts?
73
Jim W7RY
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