Hello Esteemed Fellow Coilers,
I am engaged in the long haul of building a 4x 833a coil. I have been
collecting stuff for a few years.one of my prizes are original Johnson
thumb
screw sockets in NOS condition along with Johnson heat sinks - nice
patina.
The secondary is 6" acrylic. The primary is a 8" acrylic form. Initially
it
will be running CW for tuning and power tests ( 4 used tubes cam be
toasted
alright before I turn up the new 833C's), I'll run them near red to test
my
cooling effectiveness. Duty cycle will be solely accomplished by the
staccato circuit. The secondary will be wound 24" with #21awg and will
have
a small aluminum plate on top to keep the frequency up very near 350Khz
(Fo=~348Khz) which some say is a magic number for sword like discharge.
Will
the staccato duty cycle cancel the CW hiss-like high power and cause the
CW
to behave in the aforementioned sword like discharges? I do want to
modulate
this too in CW mode (no antenna ;-^) By the way, what is the best way to
do
that sans a big modulation transformer, since we are controlling
conduction
with a SCR or? which leads to another problem- in CW filtered mode - how
do
I turn off the SCR, power off B+?
I am trying to get my head around the feedback grid coil geometry. It will
be wound on a small piece of split thin-wall PVC so it can slide up and
down
on the acrylic form. The primary is to be 3/16 soft tubing, (.1875")
spaced
by same a little over 20 turns - math looks pretty good so far. I know I
have to raise the secondary a couple of inches from the base to get K in
the
2X range (pretty tight but recommended in my readings). Cap = .003 mica in
series parallel. I may be wrong, but I don't think the grid coil coupling
to
the secondary should matter? It seems to me the field from the primary
will
swamp the secondary's influence on the feedback coil. So here's the
question
for our VTTC experienced coilers: How many turns of what size wire should
this critical grid feedback component have and should it have layers as my
former is 11"? I am fat on many wire types, magnet and PVC coated in
multiple gauges. Please keep in mind that I have a very stiff PS (big iron
and filter) that will deliver 2KW real power no sweat at full duty.
Thanks much,
Jim Mora
"The multi-tap big iron came from Tabasco Jack in San Diego, Kudo's Jack!
He
lurks here I think. It will be on its own casters separate from the coil
and
is a heavy two man/women lift! 12 taps: 3KV- 14,400.
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