[Amps] [AMPS] 3-500z "glow blue"

DAVE WHITE mausoptik at btinternet.com
Wed Apr 7 14:56:51 PDT 2010


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 at gmail.com> wrote:

From: Ryan Foster <foster.ryan at gmail.com>
Subject: Re: [Amps] [AMPS] 3-500z "glow blue"
To: amps at 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 at 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
>
>
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> Amps at 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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