[Amps] Solid State Relays Again

[Paul Hewitt]

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 at centurytel.net>
To: "amps" <amps at 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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