[huge snip, see below]
>> Antique tubes like 4-400A, 813 and 4CX250 can be pushed way above normal
>> ratings if you know what you're doing. Modern junk like 3-500Z and 8877,
>> well just look at how many people on this reflector are always looking
>> for new tubes to replace the ones that mysteriously went bad.
>> 73, Larry
> Amen to that last paragraph. A pair of 4-400's will run for many years in
> BCB 24/7 service at 1000-1200W out. Thats carrier power, the PEP is
> The 813 is my favorite for the most underated of the old time popular tubes.
> I regularly run them in AM service at a measured 210W dissipation at the
> carrier level and the graphite anodes barely show color on voice peaks. Just
> a muffin fan running at reduced voltage to move some air around.
> The problem with running over 2500V on a 3-500Z is that the IMD increases
> rapidly unless you apply NFB.
> Which Henry's run 4KV on 3-500's? Those Im familiar with are well under 3KV
> unless the choke is removed.
Henry 3KA. (2x 3-500 model) Stock in good condition and choke runs 4KV
from my 247VAC line with bleeder current. Sags some with load of course,
3600V or so.
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