[Boatanchors] Boatanchors Digest, Vol 123, Issue 34

[rbethman]

See if you can weasel one of those X-ray pieces that they stick in your 
mouth.

Tape it to the side of the tube.

You can get it processed at a Walgreens.

Bob - N0DGN



On 4/21/2014 12:48 PM, james.liles at comcast.net wrote:
> Hi Richard:
>
> I believe the blue glow on the glass is caused by electrons colliding with the glass not X-rays.  Don’t believe X-rays will occur before the elements exceed 30,000 volts at those spacings.
>
> More than likely a wayward beam element or element positioning error.
>
> Kindest regards Jim K9AXN
>
>
> Message: 5
> Date: Mon, 21 Apr 2014 08:27:38 -0700
> From: "Richard Knoppow" <1oldlens1 at ix.netcom.com>
> To: "David Stinson" <arc5 at ix.netcom.com>,
> <milsurplus at mailman.qth.net>, <boatanchors at mailman.qth.net>
> Subject: Re: [Boatanchors] "Blue Glow" mystery.
> Message-ID: <2A36AE1D8F9D476183366CCE2B32EB13 at VALUED20606295>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=original
>
>
> ----- Original Message -----
> From: "David Stinson" <arc5 at ix.netcom.com>
> To: <milsurplus at mailman.qth.net>;
> <boatanchors at mailman.qth.net>
> Sent: Monday, April 21, 2014 7:57 AM
> Subject: [Boatanchors] "Blue Glow" mystery.
>
>
>> Here's a mystery for you.
>>
>> A VT-25 in a Power Amplifier stage.
>> Key-up idle.
>> Ep = 500V.
>> Eg = -110V (cut-off)
>> Cathodes at ground.
>> No plate current, of course.
>>
>> Yet.... on the glass envelope is a small blue glow!
>> And it disappears at key-down...
>>
>> Ghosts?  Goblins??
>      The dark blue glow that seems to be right at the glass
> is caused by x-rays from the tube.  Its commonly seen in
> tubes like audio output tubes with fairly high voltage on
> the plates. Some older tubes had a black coating on the
> inside of the glass to stop it.  It does no harm.  I am not
> sure why it disappears when the tube is drawing current.  I
> think a web search may find an explanation of the physics.
>       Note that this is a different kind of glow than is
> caused by gas in the tube. That usually takes the form of a
> cloud between the elements or throughout the tube and is
> usually a lighter color. This is a dark blue and is actually
> the glass itself glowing.
>
> --
> Richard Knoppow
> Los Angeles
> WB6KBL
> dickburk at ix.netcom.com
>
>
>
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