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VACUUM TUBE COLLECTING => Tube Discussion => Topic started by: dkoczur on August 12, 2013, 03:10:34 pm

Title: Tune-A-Lite Neon Bulb
Post by: dkoczur on August 12, 2013, 03:10:34 pm
 I have a Tune-A-Lite neon bulb that is used as a signal strength/tuning indicator on an Atwater Kent Model 99 radio from 1932. It uses a Duo-vac neon bulb as a signal strength /tuning indicator. This bulb has blackened on the inside due to sputtering of the electrodes (from what I read). I saw a forum article about cleaning the inside and refilling nixie tubes that have suffered a similar problem. Could this be done on this bulb? Is there anyone who has one of the bulbs for sale. Is there any recommended place to have a repair of this type accomplished? Attached are pictures of the bulb and one showing it energized at different levels. Also I have attached a brief description of its operation.

Gas discharge tubes, primarily neon filled, were the choice for tuning indicators during the 1930?s prior to the introduction of the magic eye tube.  Inventors experimented with many different electrode configurations in their efforts to make a tube best suited for tuning and resonance indication.  This circuit uses a simple 3 element neon tube in which the neon glow will increase with signal strength.

Any help would be appreciated.


Dan K.
Title: Re: Tune-A-Lite Neon Bulb
Post by: Tim on August 14, 2013, 08:42:12 pm
Thanks for sharing pictures of this lamp in operation - it's interesting to see.  As for the lamp's darkening, there's absolutely no need (my opinion only here) to crack it open to remove the darkening, and risk ruining it forever.  Judging from the photos, the darkening doesn't look bad at all and it doesn't appear to mask the effect of the lamp when it is energized.  I've seen some neon lamps that are sputtered so bad that the neon discharge is barely visible anymore.  In that instance, it might be considered, if the lamp were scarce or valuable enough to warrant it.  Even so, I don't know of anyone doing this type of work, so it might be a moot point anyway.  These Tune-A-Lites are scarce but they can occasionally be found.  I've got a Philips version here, and also a British GEC made "Tuneon":