Re: VTTC operation, questions

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

Original poster: "sundog by way of Terry Fritz <twftesla-at-qwest-dot-net>" <sundog-at-timeship-dot-net>

Hi All!

    My tank supply is taking shape slowly.  The 10kv3A full-wave rectifier
is nearly completed, and I'm eyeballing some large filtering caps for it.
My supply of MOT's is slowly increasing (man I can't wait to go scrounge
after xmas).

  I am digging for the radio amateurs handbooks, from the 50's and up.  Flea
markets are plentiful around here, and by striking up a conversation about
ham radio with some booth owners, they usually guide me right to the correct
places to look for the books.  I've yet to find one in decent shape (2 in
horrid, missing chapters and whatnot, the other had gotten coffee or tea on
it, stained & unreadable).  But I have patience.

   I have all the stats for the 833 and a ton of other tubes on CD, so no
worries there.  With a total of 4 833's I'll be a bit above legal (okay,
waaaay illegal) power levels, so I'll keep an eye out for that non-descript
van circling the block.  But I'm thankful that VTTC's are pretty shoddy
antennas when sparking.  I can usually run mine with minimal interference in
the garage and barely any RFI, no TVI, in the house.   I plan on using my
signal gen for tuning and testing, but ultimately I'm wanting frequency,
duty cycle, and amplitude modulation (full control of the output).  A
regular transmitter, come to think of it.

   For the moment, it's a pretty quiet project.  Lots of learning, getting
the foundation for the coil built (secondary, primary, power supply), etc.
Once I gather all the parts and start building the various stages, everybody
will hear a lot more from me.  Probably along the lines of "The tube-based
Magic Smoke Machine" ;)  Many thanks to those that have contributed
knowledge and suggestions so far, and I look forward to picking the List's
collective brain!

   As always, questions, comments, criticism, and snide remarks are welcome!

Shad

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, December 09, 2001 3:02 PM
Subject: Re: VTTC operation, questions


> Original poster: "Ray von Postel by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <vonpostel-at-prodigy-dot-net>
>
> Shad:
> I couldn't agree more with the  suggestions that you look in Sam's and The
> Radio Amateur
> Handbook . Both are excellent sources.  As I understand it you are looking
> for circuitry for
> what they would probably call a "CW transmitter.". (CW = continuous wave).
> Don't expect to
> find construction details for something operating at TC frequencies.  They
> will talk about
> frequencies from above 1.5 MHz. to around 144 MHz.  Also, the power input,
> for Hams,  was
> limited by law to 1 KW.
>
> Since you are building around the 833-A it would be well to get a
> specification sheet for
> that tube.  It will give you the typical operating conditions for  the
tube
> being operated in
> CW service as a Class C amplifier.  Just remember, you will need a driver
> for the 833-A.
> It would have to put out enough power to drive the grid of the 833-A.  The
> driver stage might
> be driven by an oscillator operating at the frequency of the TC.  It might
> even be possible
> to use your signal generator to drive a lower power stage and do away with
> the oscillator
> stage.  Pulse modulation , keying, of one of the low power stages is much
> easier than doing
> so at the 833-A grid.  One particular tube configuration that comes to
mind
> is typical of
> some transmitters I have seen.    6V6 oscillator, 813 driver, 833-A final.
>
> My guess is that the two biggest problems you will have is the power
> supplies, yes, more than
> one, and winding the coils for the tuned circuits between the tubes.  You
> have an interesting
> project and I wish you luck.
>
> Ray
>
> Tesla list wrote:
>
> > Original poster: "sundog by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <sundog-at-timeship-dot-net>
> >
> >     Hi All!
> >
> >  Christmas is nearly upon us, with all the ritual last-minute shopping
in
> > overcrowded stores elbowing your way past the checkout lines in a
useless
> > attempt to find the shortest one.  Tip I learned last year, the shortest
[Snip!]