[GreenKeys] Smoke and Fire

[Bruce Gentry]

Old TVs with series string heaters were very bad for destroying the CRT 
by having it's filament flare up like a light bulb until the other tubes 
began to heat up and draw less current. Later designs used controlled 
warmup tubes and reduced the problem.  I saw a  RTTY demod unit built 
with series string "hot chassis" tubes. It was an adaptation of the 
W2PAT demod, but with no power transformer.  2 25l6 tubes were used in 
paralell instead of a 6Y6.  The input was isolated with a transformer, 
the  selector magnets were isolated from ground. Ultimately, it was 
re-packaged and fit inside a model 15
On 1/9/18 2:41 PM, David Tumey via GreenKeys wrote:
> Michael,
>
> It has been my lifelong experience that it is the JOB of the component 
> to blow up first to protect the fuse.  Your example seems to fit that 
> rule perfectly.  I know for a fact that in the old TVs, the picture 
> tube would always blow first to protect the fuse - especially if it 
> was a color tube, and the more expensive the part, the more likely it 
> would fail first.
>
> --dave
>
>
> ------------------------------------------------------------------------
> *From:* Michael Zahorik <m.zahorik at sbcglobal.net>
> *To:* drlegendre . <drlegendre at gmail.com>; Wayne Durkee 
> <teletypeparts at comcast.net>
> *Cc:* "GreenKeys at mailman.qth.net" <greenkeys at mailman.qth.net>
> *Sent:* Tuesday, January 9, 2018 1:45 PM
> *Subject:* Re: [GreenKeys] Smoke and Fire
>
> Actually the fuse is a 3 amp slow blow, which will take 3 amperes for 
> quite some time.
> Mike Zahorik (414) 254-6768
>
>
> ------------------------------------------------------------------------
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