Modulation+Plasma Tubes(Was Stereo amplifier)

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

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

Hi Terry,

A PA transformer will probably work perfect for that application (modulaton)
as might an output transformer scrapped out of an older solid state amp.
Thanks for suggesting it.

Sorry that I digressed a little bit from the original thread, and probably
confused a few people, but I feel that an audio amp could be put to better
use as a modulator rather than a driver, since RF power oscillators are so
easy to build anyway, and require less components than trying to force feed
a coil with some type of high powered driver.

I am going to digress even further because I saw something really cool last
year that can probably be easily duplicated by a lot of folks on the list,
especially the glass blower types that can fabricate a gas filled tube with
a three inch bulge in the middle and an electrode at either end. When I
visited a short wave station last year, the cheif engineer showed me the
station owner's "Rife Tube", which is the gas filled plasma tube I discribed
above. The guy connected this device to the output of a transmitter, and
connected an audio sweep generator to the modulator. As the audio frequency
was swept from 20 Hz to 20KHz, the plasma in the tube went through dramatic
changes in both color and appearance! There was a few audio frequencies that
caused the plasma to break up into a series of beads! The RF frequency
didn't seem to matter, it was actually the audio modulation that caused the
changes! We tried 7.29MHz and 3.885MHz and got the same results. This tube
was part of some fringe science device, so the gas mixture was of course
secret, but it looked like there may have been some neon, because there was
a red glow around the electrodes, Different audio frequencies caused the
plasma to either glow a light pinkish, or green. Some gas experts may know
which gasses might produce those colors.
I took photos of this, and the station posted them at their website
http://www.wbcq.us/wbcqus_077.htm

The moral of the story is that it's fun to modulate coils, and hear music
come out of the spark, but there is also a whole bunch of neat visual
effects one can get with modulation and gas filled tubes, and possibly
globes.

Cheers,
Sue

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Friday, March 07, 2003 7:13 PM
Subject: Re: Stereo amplifier


 > Original poster: "Terry Fritz" <teslalist-at-qwest-dot-net>
 >
 > Hi Sue,
 >
 > At 06:00 PM 3/7/2003 -0500, you wrote:
 > >Hi Terry,
 > >
 > >I was just curious- Have you ever tried modulating the supply voltage of
the
 > >SSTC with those amps. I was entertaining the notion of trying it when I
 > >build that mosfet coil sometime in the future.
 >
 > No.  I just feed them with sine waves from a generator.  I never had them
 > last long enough to try anything fancy.
 >
 >
 > >I figured that all one would need to do is obtain a high powered
 > >matching(modulation) transformer to match the low impedance output to the
 > >impedance of the SSTC. One winding is connected to the amp output, and
the
 > >other winding is placed in series with the SSTC power supply the same way
I
 > >did it with my tube coil. You could use an RF choke in series with that,
and
 > >then an RF bypass cap to ground to keep the coil's garbage out of the
 > >modulation transformer. The transformer itself would further isolate the
amp
 > >from the coil anyway (audio transformers don't transfer RF too good).
 >
 > Why not just ride an audio signal on top of the sine wave and feed it into
 > the line input.  Tear out the HF traps first...  The trick is to make a
 > coil with a real low Fo.  The GMHEICSLR TC ran at only 10kHz.
 >
 >
 > >I think the problem would arise in finding a beefy enough transformer
with
 > >the correct impedance match. With my tube coil it was easy because there
are
 > >quite a few modulation transformers kicking around from old Amateur radio
 > >gear, but solid state stuff has a different set of impedances. Perhaps
 > >something could be custom wound?
 >
 > I played with those 70V PA multi-taped transformers a lot.  I think Radio
 > Shack still sells them.
 >
 >
 > >Also, an older tube type high powered tube type amp, or modulator is more
 > >impervious to RF garbage than solid state amps, but even those things are
 > >worth a lot of money to Audiophools these days!
 >
 > I only had solid state.  But toob amps may do much better.
 >
 > Cheers,
 >
 >          Terry