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[AMPS] temperature variable, varistor or globar resistor source wanted

To: <amps@contesting.com>
Subject: [AMPS] temperature variable, varistor or globar resistor source wanted
From: nospam4me@juno.com (nospam4me@juno.com)
Date: Mon, 11 Sep 2000 23:03:05 -0700
need: temp variable resistors information please. 

Hello gang, 

One of my Amplifier Research NMR amplifiers went belly up. This 
wide band unit is a very interesting design. Enough tubes are 
combined in parallel to bring the output down toward 50 ohms 
for driving the output. 

The fix turned out to be an open temperature variable resistor 
in the HV supply, used for current limiting.   Replacement of the 
part brought the amplifier back on line and all is well there. 
My hat is off to AR's support for sending me the part quickly and 
providing telephone help at no charge. 

My question is about the source of these parts. I remember 
Globar type and thermistors from old tv's but I haven't seen a 
newer design using these type of resistors in some time. Hence, 
I don't know who makes them anymore.  

The original temp resistor was labeled  Keystone with a 10 ohm 
value. The AR supplied replacement part was only labeled as 
SS  with the part value CL-10  printed on the side. 

Can anyone on amps supply me with the name of mfgrs still 
producing these type of parts..?  or any useful leads on these 
type of resistors..?  Is Keystone or Globar still in business..? 

For those not familiar with these items, they appear very similar 
in size and construction to the newer MOV's used for ac line spike
protection.   Current through the part causes heating which then 
changes the resistance value.  Tube type tv's used them in the 
power supply for current limiting when the power was first  
applied.  A great early example of current inrush protection.  

anyway, thanks much. 

Replies to amps or myself direct would be greatly appreciated 
if you can help.  I'd like to buy a few to play around with.

cheers
skipp
nospam4me@juno.com 
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