--- In ham_amplifiers@..., R L Measures <r@...> wrote:
On Nov 2, 2006, at 6:46 PM, zerobeat40 wrote:
--- In ham_amplifiers@..., R L Measures <r@...>
wrote:
On Nov 2, 2006, at 2:49 PM, zerobeat40 wrote:
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.
Did you measure it or are you still depending on the data sheet?
Both. but not with a uA meter.
#### well, I just tried it on one of my 3 x L4B's.... I get ZERO
grid current with no drive applied.... whether both 3-500Z's
installed... or just ONE 3-500Z installed...... and that's with
2650 V..... doesn't matter whether I run ZERO bias... 2.1 V
bias... 4.2 v bias... or 7.0 v bias. The grid meter is a 0-400
ma deal. I suppose one could insert a Fluke 87 dvm in series
with the grid shunt.... and take a dead on reading. IF there is
gonna be any grid current.... it's gotta be pretty close to zip.
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
Did you measure that, or are you still consulting the road map
which
may or may not agree with the roads?
What's my surname?
### I think it's still Measures.
Please do not hesitate to point out errors and inconsistencies.
Never, ever.
Glad to hear it. I'm thankful for this new group, we need never
mention the old one and we'll likely be happier.
The AMPS group is doing today what it was originally designed to
do: save Tom from the problems he caused to himself during the
parasitics debate on rec.amateur-radio.homebrew - an uncensored
Newsgroup. I got booted off of AMPS 4-times for questioning Tom's
questionable statements. As I see it, a discussion group that
allows any participant to get away with technical bologna and
censors members who ask embarrassing questions is rotten.
#### The 'amps' group on contesting.com is pretty well a dead
duck these days. Last heard, they were debating drill speeds
for drilling HARD steel. Of course, someone suggested
starting with a small bit like 1/8"... then work ur way up in
size..... and use plenty of cutting fluid. The bad advice
given was recomending a speed of 1000 rpm for the 1/8" bit....
which is WAY too fast. On my vertical/horizontal bandsaw...
made for cutting aluminum, steel, and hard steel.... speeds are
200 ft per min... 120... and 80.. respectively. Of course, our
local idiot at the local tool place sez 1500-2000' per minute is
just fine for cutting thick 6061-T6 aluminium. Ditto with
using wax on Greenlee punches. Correct glop is called A-9 cutting
fluid [for aluminium] A-9 is this green glop... works great on
drill bits too... cut's like butter... just 1-2 drops needed.
### I see we are up to aprx 158 members I think... and almost 900
posting's.
### after reading 'AMPS' since day 1.... I'm surprised at the
amount of really bad advice handed out over 10 yrs.... that never
got challenged. Some of us could separate 'wheat from
chaffe'... but I'm afraid a lot of newbies just got bamboozled.
A huge amount of good idea's too in the last 10 years.
Later... Jim VE7RF
