On Nov 19, 2006, at 7:47 AM, pentalab wrote:
--- In ham_amplifiers@..., R L Measures <r@...> wrote:
On Nov 19, 2006, at 5:08 AM, Peter Voelpel wrote:
Since I prefer single capacitors as a blocker,
RICH SEZ...Single cap DC blockers have the advantage of Not
exhibiting a VHF- resonance between two or more paralleled
capacitors.
### which never happens.... IF you parallel em with WIDE AL/CU
plates on both sides. 8 x 200 pf HT-57's exhibits no
problems at all.... ditto with 6 x 500 pf HT-57's. ....or 4 x
500 pf HT-59's.
Are you saying that there is no resonance when two caps are paralleled?, or are you saying that in the amplifiers you built you have never had a problem with such a resonance? I know of a case where two caps were paralleled for the DC blocker where the VHF resonance caused a problem, which is why I brought the subject up.
### I looked at the big Draloric's, and the UK eq. For SOME
layouts... they seemed awkward to mount... cuz of the large
diam. I think the 10 kv - 60A 2000 pf ones I was looking at a
while back were 5" diam. In my case, the HT57/59's were
easily obtainable... and the 57's come in 10/15 kv... the 59's
come in 15/20/25 kv. The 50/58's come in 5/7.5 kv.
HEC makes some reasonable sized 25A or so units.
### Dunno how much safety factor one wants in a plate block
cap.... I'd like 50% min. Use what ever is available.
Dralorics here, surplus and also used... are NOT cheap.
I think I paid c. $120 each for some 25A-rated HEC's.
Later... Jim VE7RF
R L Measures, AG6K, 805.386.3734
r@..., rlm@..., www.somis.org
