Re: VTTC help

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "S Gaeta by way of Terry Fritz <twftesla-at-qwest-dot-net>" <sgtporky-at-prodigy-dot-net>


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Saturday, September 28, 2002 3:42 PM
Subject: Re: VTTC help


> Original poster: "Steven Ward by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<srward16-at-hotmail-dot-com>
>
> Oops, i missed this before my previous post.  Thanks for the schematic
Sue.
> Im a bit confused about the power input to the rest of the circuit.  If im
> simply using a MOT with only 1 HV out, do i simply connect the 2000v out
to
> the RFC and the ground of the transformer to basically everything else
that
> is grounded?

Yes, the minus of the DC current meter would go to the core, and the
positive meter lead to ground.

>  Do i skip the .8uf 2000v filter cap?  Do i need the .001 5kv
> cap as well going to ground? I also have a few questions about some
values.

Yes, skip the DC smoothing cap (That's 8uf) and the diodes. The .001 is part
of the filter that keeps rf out of the plate transformer. It's not a
critical value.
>
> What is the construction of the 65mhy RFC.  I have some 28, 26, and 24awg
> magnet wire around if i could possibly make this inductor.  I dont know
how
> to calculate that though.  What did you use?

I used 2 secondary windings off of HV transformers tossed at work connected
in series. I removed the core to make it an air cored choke. Each winding is
about a half an inch wide, and a half inch deep. The inner diameter is 1
inch, and the wire looks like 28AWG.
>
> What is the purpose for the .001 5kV cap going from 1200v to ground?

Filtering.
>
> What is the voltage rating of the .0035uf cap going from the plate to the
> primary?  IS this the cap that causes sputter mode?  Does this coil even
use
> sputter mode?!?!

No, it uses straight DC. The cap is a 4KV DC blocking cap. This serves to
isolate the tube (but not completely) from impedance changes at the load
(seconday) and adds a little safety too. Again this value is not terribly
critical.
>
> Whats the Voltage on the filament bypass caps?  What is the purpose of
> these?

I used 1KV micas, you know, the ones with the little color dots on them. It
provides the path to ground for the RF. These should be good quality caps.

>
> How critical is the value of the resistors on the grid circuit?  Would 5K
> ohm at 20W work?

This is a bit critical. Too much over this value would give less grid
current, and therefore less output. Too little and you will melt your grids.
You might be able to use 3K, but I never tried it even though I had intended
on trying it in the beginning because my grid current was too high when
things weren't tuned correctly.
>
> What is the diameter of the primary coil?  And what are you using as a
> secondary and top load?  What are all of the wire guages?

The primary is 4.5" in diameter, and the wire is 14AWG stranded. Secondary
winding is 11.13" by 2.1" and 32AWG.
>
> This circuit looks appealing, how big of a spark does the raw AC feed
give?

With 2400 volts, I got 8", but after 3 minutes one of the tubes went into
runaway condition and I shut it down quickly. Luckily, the tube was spared!
That was pushing things a bit!

> Sorry if im bugging you with all of this, but hey thats what the list is
> about;)  Thanks,

That's what we're here for! If you have any more questions, feel free to
ask.

Good luck,
Sue
>
> Steve Ward.
>
> >From: "Tesla list" <tesla-at-pupman-dot-com>
> >To: tesla-at-pupman-dot-com
> >Subject: Re: VTTC help
> >Date: Fri, 27 Sep 2002 12:23:29 -0600
> >
> >Original poster: "S Gaeta by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> ><sgtporky-at-prodigy-dot-net>
> >
> > > Well, this isnt my schematic....*snip*
> >
> >Steve,
> >
> >See:
> >http://community.webshots-dot-com/photo/8426665/48494920pFtYul
> >This is as simple as a Harley gets. I got the basic design from a 1952
ARRL
> >handbook.
> >If your 12v transformer is center tapped, just throw it on a variac, and
> >feed it 60v. Mine was also a 12v transformer, but it had a primary that
can
> >be configured for 240v. I simply fed the 240v primary with 120v.
> >
> >Good luck,
> >Sue
>
>