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Re: 833A's plate color



Original poster: "Henry Hurrass" <dr.hankenstein@xxxxxxxxxxxxx>

Thank you for the clarification, Mike.


> [Original Message]
> From: Tesla list <tesla@xxxxxxxxxx>
> To: <tesla@xxxxxxxxxx>
> Date: 3/25/2006 4:22:38 PM
> Subject: Re: 833A's plate color
>
> Original poster: "Mike" <induction@xxxxxxxxxxx>
>
> Henry,
>            While I would not run the 833a in the "super-nova" mode, the
> running of some color on the plate is quite normal.
> EVERY broadcast transmitter I ever ran which used these tubes
> ran them with some color when at normal power. That also included the
> modulator, where a pair of 833's modulated a pair in the RF final.
> One Collins rig that used to be the main transmitter, later to become
> the backup as an RCA 5 kW rig became the main rig, got very long life in
> the tubes, as one example.
> In fact, when I moved that entire AM / FM site 2.4 miles away to a new
site I
> built to switch over to, the old Collins was given to a Ham friend of
mine so
> he could convert it to 160 /80 / 40 meters AM.
> I did not have the room; The tubes continued to run long lives there, too.
> Many other broadcast rigs, using 4-1000A, 4-400's, 4-250 and 4-125's
> also ran with some color and all by design.
> Even today, there are induction heaters in use, which we service every
> few years, which run 833's with normal color. Most seem to have a
> average color.
> In these radiation cooled 833's, they seem happy. The 4-*.* family always
used
> forced air cooling, even if the filament alone was being used.
> I do find it illogical that in a Tesla Coil environment where, with
> the more common
> usage of solid state devices such as IGBT' past design parameters, such a
big
> deal would be made about running tubes with the normal color they have
been
> operated at for many decades.
> As far as China or Korean tubes go, while I see a lot used in the
induction
> and broadcast industries on old rigs (less and less these days) it
> usually takes
> buying one set to learn the lesson that they are not as well built or
re-built.
> And to show we here can compare usage's, an old 5 kw RCA induction
> heater was configured to run as a VTTC, with usual tube color and it did
> very well. We also used a Lepel induction heater later but that tube was
> water cooled.
> The RCA machine turned VTTC uses four 833A tubes. In direct to ground
> CW strikes to a pile of mud, it got steam going in no time. Not pretty
> but very functional. That rig still sits in the warehouse. So, normal
color is
> just that, normal.
> Mike
>
> ----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
> To: <tesla@xxxxxxxxxx>
> Sent: Saturday, March 25, 2006 12:49 PM
> Subject: Re: 833A's plate color
>
>
> Original poster: "Henry Hurrass" <dr.hankenstein@xxxxxxxxxxxxx>
>
> I think the suggestion that a power tubes' plate is supposed to glow a
> "dull red" during normal operation is ignorant. If the plate is glowing,
> the plate's maximum dissipation is obviously being exceeded and the life
of
> the tube(s) will suffer due to, in part, the following factors:
>
> Plate voltage too high.
> Grid voltage too low, (too small value grid leak resistor in tesla coils),
> causing excessive plate current to flow.
> Plate circuit out of tune.
>
> Of course, it is tempting to observe and enjoy the longer spark that
occurs
> when we "max out" the plate dissipation of our transmitting tubes; but
> remember, you are exceeding the maximum design parameters of the tube(s).
>
> If you want your tubes to last for years, I would never advocate running
> them with any kind of 'glow' other than the filaments. This is good just
> plain good design etiquet. But thain again, they're you tubes, so if you
> want to run them in 'supernova', be my guest. Just remember what others
may
> be thinking when they watch your TC's plates overheating.
>
> Dr. Hankenstein
>