Author: "Jim Brown K9YC" <k9yc@audiosystemsgroup.com>
Date: Tue, 27 Nov 2007 11:41:28 -0800
Crew, I'm thinking of following N6LF's advice on a rebuild of my 160 vertical by tuning it low and adding series capacitance to tune out the resistance to match it to 50 ohms. Legal power will put ab
ORIGINAL MESSAGE: -- REPLY FOLLOWS -- As a general rule, I would avoid putting the caps in series because you never know exactly how the voltage will divide across them due to minute differences in l
That is only an issue with DC, which doesn't apply here. In the DC case, the standard fix is to put swamping resistors across the caps. Rick N6RK _______________________________________________ _____
Jim, I would be surprised if your 10 - 100nF 400VDC capacitors are capable of taking 6 amps at 1.8 Mhz, without excessive heating and drifting. Therefore your only option is to parallel the 100 to 50
ORIGINAL MESSAGE: -- REPLY FOLLOWS -- Not so. The voltage division vs leakage issue applies at any frequency. The capacitor responds to the instantaneous voltage at any moment in time, AC or DC. 73,
But for any frequency where the impedance of the C is much less than the leakage, it will be the tolerance of the C value that determijnes the split. Since most caps are no worse than 20%, that's pro
ORIGINAL MESSAGE: On Thu, 29 Nov 2007 09:05:19 -0800, Jim Lux <jimlux@earthlink.net> wrote: -- REPLY FOLLOWS -- Murphy is waiting. :-) 73, Bill W6WRT _______________________________________________ _
I don't understand that comment. Murphy's Law has nothing to do with it ... Ohms Law does. As N6RK said, where high voltage DC is present, capacitors in series are typically bridged by high value par
Thanks for the many excellent thoughts on this issue. Based on the contents of my junkbox, I began with two .0047 400V dipped micas in series, and pumped 1 kW through them for a few minutes. They got
Author: Martin Ewing - AA6E <aa6e@ewing.homedns.org>
Date: Thu, 29 Nov 2007 15:56:39 -0500
Let me jump in with a pet peeve. I know Jim knows better, but there are few components that know or care how much power is "pumped through" them, although people often speak as if they did. Capacitor
Except that Jim did exactly what he said he did: he ran a qualitative power-handling test of some capacitors he had on hand. He apparently instrumented only one value, RF power on the source end, and
through" Oh, but capacitors DO care (or at least WE care) what power they're dissipating. Yes, it's current and I squared R or voltage and E squared divided by R, where R is the ESR in the case of cu
--Original Message-- <snip> Back when I was building high power tesla coils and Marx banks, I discovered that capacitor prices (and sizes) tend to be proportional to energy storage. Say you needed 1
Hi Jim, Whilst polypropylene dielectric capacitors can be put to good use in RF bypassing circuits, the one point you overlooked is their capacitance shift with temperature. Whilst I have not seen th
--Original Message-- Interesting point... In tesla coil or high reprate Marx applications, capacitance stability isn't a huge issue (although.. 5% change is enough to put you "out of tune" on a TC..
ORIGINAL MESSAGE: -- REPLY FOLLOWS -- Murphy will be glad to provide you with the occasional capacitor which has considerably more leakage than another. In a parallel circuit, this may be of no impor
I don't think you get it yet. Normally I'd let it go but you're going to mislead a lot of people here if I do. The original question involved capacitors in the range of 1000 pf, which at 1.8 MHz have
ORIGINAL MESSAGE: -- REPLY FOLLOWS -- I get what you are saying. You don't get my warnings about Mr. Murphy. Food luck to you, you'll meet him someday. :-) 73, Bill W6WRT ____________________________
I'm not so sure that you do either. :) There is leakage, there is stray inductance, and there is a series loss component. ALL of these factors are at play, not just one. FWIW -- I posted the original