[Amps] Thermistor's.

[Jim Thomson]

From: "Randall, Randy" <Randy.Randall at healthall.com>
Subject: Re: [Amps] soft start, how to determine if needed?

No so.  I had a RCA CTC-9 (Circa 1959-60) with a 21" round crt that used a ?thermistor? in the transformer's primary and it did open up.  Not having a ?replacement handy I just shorted the leads and powered on.  The set never made ?a sound powering up before, but after there was a loud bummmmmmm when the ac ?was applied.  This set did not have an automatic degaussing circuit.?

Randy AB9GO ?


Subject: Re: [Amps] soft start, how to determine if needed?

ORIGINAL MESSAGE:

On Sun, 28 Feb 2010 09:58:56 +0200, "Alex Eban" <alexeban at gmail.com>
wrote:

>By the way, an old trick that was used in tube type TV sets was to install a
>thermistor in series with the mains.

REPLY:

That thermistor was not used for soft start. It was part of the
degaussing system and had very poor reliability. I changed hundreds of
them over the years. Not recommended.

73, Bill W6WRT


###  Bill, are you trying to tell us that  every thermistor listed in every current catalog doesn't work ?? 
If RCA thermistor part # XXX   kept blowing up by the hundreds, then obviously it was SIZED wrong. 
If a B+W 800 plate choke blows up on 15m, the replacement will blow up as well, so will the 3rd one.
If the Emtron plate choke blows up on 17m, and it's replacement  blows up as well, what do you think
will happen the 3rd time around ? 

##  There are lots of folks who have used RF parts  thermistor's  for FIL  step start [not plate xfmr's].. and 
have never had a problem.

##  too bad they don't put a thermistor inside a newly designed ceramic  incandesent light bulb fixture [ designed to take heat]
then you would never be replacing bulbs ever again. A 1000 hr  bulb now becomes a 100k  hr  bulb.

later...... Jim   VE7RF  



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