"Chuck Grandgent" <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Wow.
In this case I'm suspecting that the tube itself had problems, as the
"new" one behaves much different.
However, I will certainly check R100, R101, etc., and generally poke around.
Thanks !
Chuck, K1OM
On Sat, Mar 29, 2008 at 7:07 PM, Dennis Monticelli
<[EMAIL PROTECTED]> wrote:
>
> "Dennis Monticelli" <[EMAIL PROTECTED]> made an utterance to the drakelist
> gang
> ----------------------------------------------------------------------
> Overload occurs after the entire cathode (inside of the cylinder) has
> been lit. At this point the tube is saturated and any additional
> current will cause the regulated voltage to significantly rise and
> thus overheat the tube shortening its life. But your tube had some
> flicker. Flicker is caused by small regions of negative resistance in
> the current vs voltage curve ("pips")that develop over time. The
> discharge jumps from one region to the other on the cathode, hence the
> flicker. I have seen this before and there are two solutions. One,
> change the current through the tube to a different level (higher of
> lower) to get away from the negative resistance region. Be sure to
> stay within current ratings if you do this.. Two, just replace the
> tube as you did. Flicker causes noise in a receiver and can give an
> interesting light dance in a dark room. I had this occur in my TO
> Keyer.
>
> I have also seen the flicker accompanied by a bright localized
> discharge (just like you described); not to be confused with the
> localized dull orange region of a tube operating just above minimum
> current. I don't know what causes that but I'm guessing gas has
> intruded or been internally outgassed and that gas has contaminated
> the pure existing gas causing the ionization path to become
> concentrated (ie. bright). I experienced this in my R4B, and let me
> tell you, it was quite a light show. It scared me enough to abruptly
> kill the power thinking there was a tube that had developed an
> internal short. A new regulator tube fixed the problem.
>
> So these simple regulator tubes are not so simple after all when it
> comes to failure mechanisms.
>
> Dennis AE6C
>
>
>
> On Sat, Mar 29, 2008 at 2:58 PM, Chuck Grandgent
> <[EMAIL PROTECTED]> wrote:
> >
> > "Chuck Grandgent" <[EMAIL PROTECTED]> made an utterance to the drakelist
> gang
> > ----------------------------------------------------------------------
>
>
> > I'd noticed my OB2 in my R4A starting to flash or flicker bright
> > orange, maybe a little reddish tint. First only at startup, then more
> > and more.
> >
> > So I got a "new" OB2 and now have only a continuous orange glow from
> > the base area, without any flickering.
> >
> > What precisely are the failure modes of these regulator tubes ?
> >
> > Chuck, K1OM
> >
>
>
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