> >this. In all but one case, I am talking about Thoriated Tungsten
> >tubes rated from 500 W to 250 kW dissipation, but they are also used in
> >linear class AB 1 or 2 service. BUT I am not dealing with communications,
> >where 2 tone IMD and such is a problem.
>
> Presumably, if there's enough emission for a given carrier level, there's
> enough for the same pep.
The problem everyone seems to miss, and it certainly is a problem,
is that amateurs have varying drive power from band to band.
Amateur operators tune the amplifier differently from time-to-time
and certainly from band-to-band, and the amplifier itself varies in
characteristics from band-to-band.
It is poor thinking to attempt to copy commercial single band
applications that use ONE mode, in amateur service. That's
especially true is the person making the adjustments doesn't set
emission under worse case conditions.
For example, you could not possibly set the SSB filament
emission correctly by looking at a CW signal...because the HV
and often the exciter power are higher on SSB peaks than they are
on CW peaks. That means more peak emission current for SSB.
On some bands (typically ten meters) peak emission for a given
output is higher, so now we have added a new dimension of
concern.
All of this will almost certainly be poorly handled, no one will watch
IMD or be sure they are setting emission under maximum demand
conditions, just to cure what amounts to a "non-problem" because
we want to copy what single-frequency single-emission 24 hour
operation people do.
I'd wager more than 50% of the people wouldn't even set or
measure filament voltage correctly, let alone do a proper emission
evaluation.
Certainly we don't want to run filaments at more than
recommended voltage, and it would be helpful to tell people how to
properly measure filament inrush and voltage, but anything beyond
that is foolish.
73, Tom W8JI
W8JI@contesting.com
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