[SignalOne] The Notorious Surgistor

[WQ9E at btsnetworks.net]

Ed,

I installed an inrush current limiter purchased from Mouser when I went through my CX-7A 2 years ago.    I can't remember now which one I used for the Signal One but you should choose one that has a current rating slightly greater than the expected maximum steady state current and a rather high cold resistance.  Here is a link to the Mouser catalog page:  http://www.mouser.com/catalog/catalogUSD/642/584.pdf

These are negative temperature coefficient devices and do a good job of limiting inrush current.  I use them in a variety of vintage gear to reduce stress on switches, transformers, filaments etc.  I have been using them for over 10 years and have not had any failures yet.  The only real installation caution is that they do get hot in use so don't put them next to or directly under anything that doesn't like heat.  Jim Garland wrote a nice article in Electric Radio on their use in a Viking 500 so if you subscribe to ER you might want to take a look at his article in issue 99 (July 97).

Rodger WQ9E

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From: EDWARD SCHUMACHER <edwa9gqk at yahoo.com>
Sent: Tuesday, October 12, 2010 8:27 PM
To: signalone at mailman.qth.net
Subject: [SignalOne] The Notorious Surgistor 

This list is for discussions regarding collecting, repair, use and sale of Signal/One radios and accessories. 

Documentation on Signal/One radios can be found at http://www.hamanuals.com and several other sites on the Web. 

.
Well, it has finally happened to my radio too. The notorious surgistor (which 
was actually a recommended add to the early CX7's and became standard) has died 
in my radio. I have just finished plugging in the new nixie driver chip and 
installed one of my NOS 8072's and now the surgistor has finally cracked 
through. It was admittedly in bad shape when I got the rig so I knew final 
failure could happen anytime, just wish it wasn't today, HI!

I know many have asked about replacements for this device but I have not heard 
of any successes. I have a copy of an e-mail from back in '05 where someone 
claims to have gotten some sort of replacement from Digikey but never gave the 
specific info. Can't believe it was an actual Workman FRT2 though. I have not 
been able to back reference the spec on the Workman device so I cannot tell what 
else might work. Anyone out there who has done this, would sure appreciate 
hearing from you. As a last resort I will just develop a start resistor/relay 
setup like in the linears.

Thanks and 73 ... Ed, WA9GQK

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