There must be a resistance across the filament pins on the weaker glowing tube.
Ohms law does not lie!
Check the tube socket filaments pins carefully on the weaker glowing tube with
an VOM with both tubes pulled out.
.... Bill K3HZP
---------- Original Message ----------
From: David Gow <6146guy@gmail.com>
To: Victor Rosenthal 4X6GP <k2vco.vic@gmail.com>
Cc: amps <amps@contesting.com>
Subject: Re: [Amps] 2K Classic X filament issue
Date: Tue, 3 Aug 2021 13:43:36 -0700
Oops, you are correct. I must have been thinking of one of my past
SB-220s. Being series makes it a real mystery.
Dave W7VM
On Tue, Aug 3, 2021 at 11:56 AM Victor Rosenthal 4X6GP <k2vco.vic@gmail.com>
wrote:
> I would have said the same, except that the filaments are in series.
> That implies that the same current must be flowing through both of them.
> If one set of contacts is dirty, then the current through both tubes
> would be reduced.
>
> 73,
> Victor, 4X6GP
> Rehovot, Israel
> CWops #5
> Formerly K2VCO
> https://www.qsl.net/k2vco/
>
> On 03/08/2021 20:58, David Gow wrote:
> > I had the same on my 2KD-3. Turned out the tube socket pins on one
> > socket were a little dirty/corroded. Cleaned and tightened them and
> > all is well now. Dave W7VM
> >
> > On Tue, Aug 3, 2021 at 10:44 AM Donald Fox via Amps
> > <amps@contesting.com> wrote:
> >
> >> Gents: As you may recall, I have a soft spot for the Henry Classic
> >> consoles. I recently acquired a 2K Classic X console from the
> >> original owner, and want to being it back to life. It's interesting
> >> to note that This 2KX was originally built as a domestic 2KX, with
> >> the smaller plate xformer. The owner eventually purchased the
> >> larger export 1171 plate xformer, and installed it. The amp was
> >> purchased from AES in Wickliffe, Ohio, back in the early 80's, and
> >> used frequently until the owner left town in 1986. From then on, it
> >> sat unused for 35 years.
> >>
> >> After a thorough cleaning, I am seeing a brightness difference in
> >> the 3-500z tubes. I tried swapping the tubes from front to back,
> >> and the front tube consistently has the weaker filament. I have
> >> also tried a second, known good set of tubes, with the same
> >> results. A visual inspection of the underside of the RF deck
> >> revealed no obvious problems. Filament voltage is around 11
> >> unloaded, as the filaments are in series.
> >>
> >> I have not enabled the HV section as of yet. The bearings in the
> >> blower were semi frozen, such that a new motor was required. That
> >> part is done.
> >>
> >> Thoughts and suggestions please.
> >>
> >> TIA
> >>
> >> Don N8ECH _______________________________________________ Amps
> >> mailing list Amps@contesting.com
> >> http://lists.contesting.com/mailman/listinfo/amps
> >>
> > _______________________________________________ Amps mailing list
> > Amps@contesting.com
> > http://lists.contesting.com/mailman/listinfo/amps
> >
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