[Amps] Solid State Relays Again

Paul Christensen w9ac at arrl.net
Mon Feb 10 07:01:39 EST 2014


I ran into something similar a while back.  It looks like the Crydom D2440 
is available in both zero-crossing and random turn-on (RTO) types.  Most SSR 
manufacturers recommend using zero-crossing SSR's only for resistive loads. 
(e.g., see http://www.crouzet-ssr.com/english/faq.shtml#p04 ).

If your Plate Xfmr SSR is of the zero-crossing type, maybe a simple change 
to an RTO model will help.

Paul, W9AC

-----Original Message----- 
From: Jim W7RY
Sent: Sunday, February 09, 2014 10:13 PM
To: amps
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
I looked at the archives and read a debate between Ian and Paul about
this exact subject. Any new thoughts?

Jim W7RY

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