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Re: [Amps] Crydom Solid State Relays

To: bmaser@tampabay.rr.com, amps@contesting.com
Subject: Re: [Amps] Crydom Solid State Relays
From: TexasRF@aol.com
Date: Thu, 29 Jan 2009 12:05:41 EST
List-post: <amps@contesting.com">mailto:amps@contesting.com>
A couple of comments from a user: The solid state relays do not completely  
shut off in the off condition; you will have some residual voltage on  the 
output terminal when you might expect zero volts.
 
The 40 ampere rating can be exceeded with a capacitor type filter circuit.  
It has been mentioned many time in the past that peak ac current can be 5 to 10 
 times average with capacitor filters. Solid state relays don't like  this. 
You might want to consider 70 amp rated relays as they  don't cost that much 
more than the 40 amp units.
 
When one of the SSR's fail, it is invariably in a shorted mode. Needless to  
say, this is an extreme safety hazard. Never assume that a power supply is 
off;  it may not be!
 
73,
Gerald K5GW
 
 
 
 
In a message dated 1/28/2009 7:08:01 P.M. Central Standard Time,  
bmaser@tampabay.rr.com writes:

The  power supply of my new amplifier will be using 3 40A Crydom SSR relays,  
One on each leg of the 240VAC and another in one leg to short out the step  
start resistor.  I have been planning on using the SSR's w/o any  resistors 
or capacitors across the control connections but I have been  advised that I 
should put resistors and capacitors across the control  connectors to prevent 
RF from affecting the SSR function and possibly  causing "chatter".   I would 
appreciate some feedback from the  group.  I don't believe that Jerry 
Pittenger K8RA used anything in  the 3CX1500D7 amp that was featured in the 
2006 ARRL Handbook.

Bob  Maser  W6TR  

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