On Nov 2, 2006, at 2:49 PM, 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.
Not with several volts negative on the grid with respect to the cathode.
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.
hardly
Please do not hesitate to point out errors and inconsistencies.
Never, ever. This is what got me jackbooted off of AMPS, Zed. Examples of statements that I questioned: AC circuit analysis does not work with R/L VHF parasitic suppressors; Ni-Cr alloys (a.k.a. resistance-wire) has reverse skin effect as frequency decreases; VHF- resonant circuits can not ring when pulsed; dip=meters are unreliable, over-driving an SB-220 can produce 3x the normal pk-V in the anode circuitry, on and on in the world according to W8JI.
There
are days when I am amazed that I remember which end of a fork to hold.
Forrest Gump was right, Zed, and it definitely happens to us codgers.
cheers
Z
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