RE: [TCML] RQ HV RF filters on PT HV

["Lau, Gary" <Gary.Lau@xxxxxx>]

The ability to withstand voltage reversals reflects the losses in a cap's dielectric.  The ability to withstand the cap's charge being directly short-circuited reflects the ability of the cap's plates and electrical interconnects to survive huge current pulses.  While both features are desirable in caps, they are unrelated - one has no bearing on the other.

I think that Barium Titanate caps and ceramic caps in general can't hold a candle to the CD 942C series caps that we use, in terms of both current ratings and dielectric losses.  Barium Titanate caps survive in tank cap applications because many are typically used in parallel, reducing the current per each.

I use doorknob caps in my Terry filter, because the resistors reduce the current to a very low level.

Regards, Gary Lau
MA, USA



> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> Behalf Of Jim Mora
> Sent: Wednesday, December 24, 2008 12:21 AM
> To: 'Tesla Coil Mailing List'
> Subject: [TCML] RQ HV RF filters on PT HV
>
> Hello all,
>
> Lets take a trip down memory lane to "94" from "circuits" in the archives:
>
> "BC1 is a Bypass Capacitor. I use high voltage barium titanate
> doorknobs, with stacks of four or more in series. A typical
> rating for a single cap would be .003 microfarad -at- 30 KVDC, and
> using four of these caps in series I get .0007 microfarads at 120
> KVDC. Since the AC rating is about half the DC rating on these
> type capacitors, figure a series stack of four will withstand a
> kickback of 50-60 KVAC in this use.", RQ
>
> RQ also talks about using iron core 15 turn HV chokes downstream which I
> know have been jointly discontinued. I still wonder if the Barium Titanate
> caps can take the gap closures since they do take voltage reversals pretty
> well. What am I missing???
>
> "I don't know if pole pigs and PT's actually benefit from Terry filters, but
> the bypass caps will clearly benefit from the use of resistors.
>
> Regards, Gary Lau
> MA, USA" *** well put***
>
> Thanks,
> Jim Mora
>
>
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