On Nov 2, 2006, at 3:30 PM, Tony King - W4ZT wrote:
I would expect, at that plate voltage and 3-5 volts bias you'd have
significant ZSAC... but I'd think that grid current, if any, with no
drive would be measured in microamps. True?
Probably pico-A with 5v of reverse bias.
73, Tony W4ZT
zerobeat40 wrote:
--- In ham_amplifiers@..., R L Measures <r@...> wrote:
True enough, Denny
Z. I did the same experiment when I was in college. Zeb's problem
is that he is the person who said:
#643
Re: SB-220 Questions
"With 3.5kV applied, a
good tube in one socket, and +3-5V on the cathode with no RF drive,
you should have about 20mA grid current in the normal direction."
- Z
My word, did I write that? At my age, I am often guilty of mis-types
of all sorts. 20 mA is far more than I would expect, and I seem to
recall that I did the experiment shortly after writing about it here.
I probably posted the results as well. Certainly there is grid
current in the normal direction. As long as the tube is not cut-off,
it is a guarantee that some electrons will intercept the grid. Grid
current will not be zero unless the tube is cutoff.
Please do not hesitate to point out errors and inconsistencies. There
are days when I am amazed that I remember which end of a fork to hold.
Z
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