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
________________________________________________________________
YOU'RE PAYING TOO MUCH FOR THE INTERNET!
Juno now offers FREE Internet Access!
Try it today - there's no risk! For your FREE software, visit:
http://dl.www.juno.com/get/tagj.
--
FAQ on WWW: http://www.contesting.com/FAQ/amps
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
|