[Amps] Question about glowing 3-400z's

[Gary Smith]

The higher the frequency, the more the color changes from a red glow towards 
white. (From 80/75m to 10m)
73,
Gary...wa6fgi

----- Original Message ----- 
From: "Scott Townley" <nx7u at arrl.net>
To: <w2cqm at juno.com>; <amps at contesting.com>
Sent: Sunday, July 09, 2006 8:44 PM
Subject: Re: [Amps] Question about glowing 3-400z's


>I would say that, considering the idle plate dissipation is 260W/tube, that
> some color would be expected.
>
>
> At 19:25 2006-07-09, w2cqm at juno.com wrote:
>>I'm working for the first time on a pair of 3-400Z's in a Swan Mark I. On
>>both the high and low power position,   the amp is making exactly the
>>instruction  manual's specified idle current. Plate voltage is 2900VDC and
>>idle current is 180ma.  With key down and no excitation at this
>>level,  the tubes begin to glow  to a  color that  I consider to be a
>>bright red. The plate current meter shows no rise in current draw during
>>this entire  process.   The amplifier loads perfectly and when driven with
>>100w ,  power output is about 1100W. The question is whether this
>>"glowing"  is the normal characteristic of a  pair of  Eimac tubes?? Any
>>comments will be appreciated. Ron W2CQM/3
>>
>>
>>
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>
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