> Why does everyone insist that the 4-1000 needs in excess of 5kV to run
> legal limit?
Because they use a different power meter than you do? A Bird 43
is spec'd at + - 5% of full-scale anywhere on the scale, IF it is
properly working.
Maybe because the "low-gain" amps are laid out to NOT have
regeneration? Feedback is an old trick to increase gain.
I have built several that easily put out 1500W with only
> 4-4.5 kV and 100W from a solid state rig. Am I just using good tubes
> vs. ones near the end of life? Probably.
4-1000's should have low gain in grounded grid, because the driving
impedance of the tube is fairly high compared to other tubes. The
driving impedance of a 4-1000 is noticeably higher than that of a 3-
1000 or 3CX1200, which barely make 1500 watts at 3600 volts with
100 watts of drive.
While you might get around 1500 watts/100watts with around 4500
volts, it just won't happen at 4kV unless something "funny" is going
on in your equipment. The driving impedance of the tube is too high
for much more gain than that in GG, without some form of
regenerative feedback.
By the way, 100 watts from a solid state rig is the same as 100
watts from a tube. As long as the PA has a low pass input filter
with enough Q and is stable, it doesn't matter what you drive it with
or how long the coax is.
73, Tom W8JI
W8JI@contesting.com
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