RE: [TCML] Wanted (6) 8020 Vacuum tubes, RF filtering

["Jim Mora" <jmora@xxxxxxxxxxx>]

Hi Ed,

I'm going to buy the tubes from Jim H. as the unit is self contained
(sockets and the filament transformer is internal with the HV
transformer)The PS is from a decommissioned military installation. This will
connect to a 20" ASRG with (8) 3/8" tungsten electrodes. I guess RF won't
matter with the tubes and I have a large 3 phase EMI filter for the LV side
which will go near the 3Phase 208V wye source. I'll post a picture to my
blog space when the tubes are plugged in the supply - very Frankenstein-ish.
The top plate supply insulator(it's tiered) and output insulator are 16"
high! It was manufactured by Raytheon. The transformer oil tests below 40PPM
PCB as there are no capacitors.

If anyone recommends doing RF filtering on the DC 24KV out side I would like
to read a post!

Thanks Much,
Jim Mora

-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of Ed Phillips
Sent: Saturday, November 17, 2007 12:28 PM
To: Tesla Coil Mailing List
Subject: Re: [TCML] Wanted (6) 8020 Vacuum tubes

Jim Mora wrote:

>Hello All,
>
>I am looking for (6) high conductance 8020 HV rectifier tubes and maybe a
>spare, at reasonable pricing. New old stock would be great! Otherwise, I
>would probably want to test them for near = conduction. This is for my 3P 6
>pulse radar transformer for a stiff DCHV PS.
>
>Otherwise, I will use a stack of 6 each 7500v 4a puck diodes (which I
>already have) in place of the tubes - just about the right height. The
>output has a 150 H reactor in the tank! Will any RF get past this back into
>the diodes?
>
>Thanks,
>Jim Mora
>
    Why not just use the diodes?  Of course if you have the sockets and 
more importantly the filament transformer that's a bullet prooof way to 
go.  As for the reactor, I wouldn't depend on it to keep "any RF" from 
getting through as it will have some distributed capacitance which WILL 
result in feed through.  Good RF bypassing after an RF choke would be 
advisable, with the cutoff frequency way below your intended operating 
frequency.

Ed

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