>
>
>--- 2 <2@vc.net> wrote:
>
>> The 3-500Z is difficult to damage from excessive
>> grid current because it
>> has a grid that can be run at red-heat for brief
>> periods without a
>> problem. My guess is that the grid contains
>> molybdenum. Tune for max
>> RF out with c. 65w drive and grid-current will be
>> good.
>
>At ~65 watts drive I get 130ma grid, 450ma plate
450mA is in the non-linear region of the constant-current curves.
>and~700 watts out. Power levels are an estimate. My
>tuner meter was adjusted to match a Bird meter as
>closely as possible, (some time ago). The accuracy
>varies depending on where in the tuner meter's scale
>it's running. Anyway, I tend to stay at or under
>Henry's recommended 400ma Ip and 130ma Ig.
>
>> >> Your 3-500Z may be distorting because it is
>> running
>> >> out of emission due
>> >> to the use of c. 5.8v on the approx. 4.8v
>> filament.
>> >> When a 1KD-5 is
>> >> operated in Japan, where they have 200v mains,
>> the
>> >> filament v. is ideal.
>> >
>> >Interesting. This possibility I never considered,
>> >since I was able to get good output ( 600 watts or
>> so
>> >) with reasonable drive. Since I don't know what
>> the
>> >orignal transformer supplied, I can't say first
>> hand
>> >what the conditions were before I got the amp.
>> >
>> With a stock amp., it is helpful to have a free
>> supply of new tubes.
>
>Well.... I measured the fil. volts. You were right...
>5.85V at the tube pins. And this is with THEIR
>replacement XFMR for this unit.
>
I dropped a 1KD-5's stock fil. potential by 1.0v to 4.8v. I accomplished
this by using smaller gauge wire in the filament ckt. Teflon insulation
is best.
cheers
- R. L. Measures, 805.386.3734,AG6K, www.vcnet.com/measures.
end
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