Re: 811A first light

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

Original poster: "Dr. John Gudenas by way of Terry Fritz <twftesla-at-qwest-dot-net>" <comsciprof-at-ameritech-dot-net>

Hi Brent
No argument, I should have elaborated more on "device". Note the size of my
grid leak resistor just to keep three 811A's happy and allow run time up to
4 minutes before the plates are cherry red and this is around 500 mA.
However, all is about to change. I was with Bert Hickman at a local Ham fest
last weekend and picked up a NOS  GE 4-1000A and Eimac socket. I have a
plate transformer from an old TV station and all the other parts I need (but
time). When it lights, I'll post the list. Thanks for filling in the
details.
John W. G.
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, July 10, 2001 9:08 AM
Subject: Re: 811A first light


> Original poster: "Brent Turner by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<bturner-at-apc-dot-net>
>
> Hi -
>
> Having built a VTTC myself (pair of 805's), I used a MOT from an
> industrial oven. Had two 1100 volt windings in series which paralleled
> quite nicely for 500mA output. Drives my 805's directly with no current
> limiting.
>
> You shouldn't need current limiting in the transformer anyway. The
> grid-leak bias (variable resistor across a capacitor, whole thing in
> series with the grid) establishes not only a slight phase delay, but
> also limits the plate current.) is adjusted so that plate current falls
> within the tube's plate spec's. The tubes are not driven into full
> class-C operation in the classic VTTC circuit.
>
> - brent
>
>
>
> Tesla list wrote:
> >
> > Original poster: "Dr. John Gudenas by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <comsciprof-at-ameritech-dot-net>
> >
> > James
> > The 811A can only handle 175 mA on the plate -at- around 1500 volts. If you
use
> > a MOT with out any current limiting device you will likely melt the
plate.
> > Check out my triple 811A coil on:
> > www.scifair-dot-org/hvdata
> >
> > John W. G.
> >
> > John W. Gudenas, Ph.D.
> > Department Chair of Computational and Natural Science
> > Aurora University
>
>
>