A blue glow on the glass has been around since at least the old 42 and 45
tubes of the 20's and its nothing to worry about. I have several vintage
console radios that Ive restored and use and I enjoy looking in the back and
seeing a brace of 2A3's, 6L6G's etc merrily glowing away.
When the glow is deep inside by the cathode then you have gas.
Carl
KM1H
----- Original Message -----
From: "DAVE WHITE" <mausoptik@btinternet.com>
To: <amps@contesting.com>; "Ryan Foster" <foster.ryan@gmail.com>
Sent: Wednesday, April 07, 2010 5:56 PM
Subject: Re: [Amps] [AMPS] 3-500z "glow blue"
If I key down with my 4-1000A amp tuned up, I can see a faint blue glow
around the glass, looking from above - but I thought that was normal
Dave G0OIL
--- On Wed, 7/4/10, Ryan Foster <foster.ryan@gmail.com> wrote:
From: Ryan Foster <foster.ryan@gmail.com>
Subject: Re: [Amps] [AMPS] 3-500z "glow blue"
To: amps@contesting.com
Date: Wednesday, 7 April, 2010, 22:05
I changed the subject so I don't hijack the thread.
What does "Tubes do not glow blue" mean? What don't I know about blue
glowing tungsten filaments? I've never seen this and never heard of
it.
--Ryan w8cya
On Wed, Apr 7, 2010 at 11:43 AM, JayKay <pcb4u@verizon.net> wrote:
> HI all
>
> Need some help. I have a friends SB220 that does not accept RF drive.
> Following info
>
> 1) Plate voltage good at tubes
> 2) Looks like 30 ohm parasitic resistors/cap (aftermarket) are good, both
> tubes
> 3) Relay closes...TUNE position plate idles at 100ma
> 4) When relay closed I do have a DC path from RF input via relay to tube
> just prior to .01uf coupling capacitor.
> 5) In standby RF path good from INPUT to OUTPUT
> 6) Tubes do not glow blue
> 7) The tubes appear OK (physically), passed the "shame next to ear" test
> 8) No grid current
> 9) Driving rig (TS950) shows INFINITE SWR which (to me) indicates an open
> or short (RF wise) in input.
> 10) 5 volt zener OK when relay energized
>
> I am thinking it could be the .01uf coupler to the filaments
>
> Thoughts?
>
> Jay
> W2IJ
>
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
--
"If someone has a gun and is trying to kill you, it would be
reasonable to shoot back with your own gun." -- The Dalai Lama, May
15, 2001
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