Glowing Tubes Not During Christmas!

[Harvey A. Kader]

Bob Meyer wrote:

> Getting to heath HI-FI amps,
> I have a bunch here I use all the time.
> On the W-5m which I use 2 for stero.
> I am using RCA black plate 6L6GC now and I get
> a little red glow on plate.only can see it in the dark.
> Is this ok ? the bias current checkes ok.pulled cathode off and put MA meter in line.
> The sovtek 6L6GC does that also even the A9-C amp does this.
> The GE 5881 does not have the red glow on plate.The sovtek KT 66 does not eather.or does the svetlana 6L6GC.
> My JAN GE 6L6WGC did not eather but are week now after a few years.like 5.
> The china 6L6GC has a orange glow on the plate and did not last.JUNK!! looks like a 6V6 in a bigger bulb.
>
> Thank you,
> Bob
>
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Hi Bob.

Just a note to let you know that NO tube should have ANY glow(red or orange) on its plates. Such a glow
indicates TOO MUCH current running through the plates(for example 80mA versus 40mA). Glowing tubes will self
destruct sooner or later - the higher the excess current, and the more intense the glow, the faster the tube
will destroy itself.

Thermal runaway is an example of a condition which produces a very glowing tube.

As far as Chinese tubes are concerned, the small signal tubes are great(I have had zero problems with them), and
the quality of the output tubes is increasing( slowly).

I hope that this helps.

Regards.

Harvey A. Kader
http://www.angelfire.com/on/vacuumtubes
http://www.geocities.com/tubesforsound

Sponsored by the City of Tempe 

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