On Nov 18, 2006, at 7:29 AM, pentalab wrote:
--- In ham_amplifiers@..., R L Measures <r@...> wrote:
On Nov 18, 2006, at 1:42 AM, pentalab wrote:
### Jenning's told me, IF you are going to use.. say
a FIXED vac cap... as a PLATE BLOCK CAP [don't laff... LOADS of
11m QRO amps use fixed ceramic/glass vac caps as plate
blockers... mounted vertical... connected with a special clamp,
to
the center anode typ .82" solid pin] that the vac cap has to be
DE-RATED by 60% for V. IE: For an amp with say 7 kv no load
HV supply.... use a min of a 20 kv test rated vac cap.
RICH SEZ... A 15kV - tested Tune-C would do the job - provided that
the DC blocker cap was ahead of the Tune-C. With a 7000V anode
supply, and a g-g triode, the AC anode potential would be c. +/¨C
6700V-peak. Since the RF rating of a vacuumis 60% of it's DC
rating, or 9000V in this case, a 15kV cap would do the job. -
note - The "Plywood Box" amplifier used a 15kV tested Tune-C and a
9000V NL anode supply. The Tune C did not arc.
### Rich, when are u gonna read the posts more carefully ???????
Sorry.
We are talking about using a FIXED vac cap.... AS A PLATE
BLOCKER !!!!!!!!!!
A 20kV rated C to block 7000V DC sounds like over-engineering since
the actual AC potential across the blocker is minimal.
R L Measures, AG6K, 805.386.3734
r@..., rlm@..., www.somis.org
