Date: Fri, 01 Mar 2002 09:41:22 -0700
Message-Id: <4.1.20020301091659.011ea7a8@pop.dnvr.qwest.net>
From: "Terrell W. Fritz" <terrellf@qwest.net>
Sender: owner-tssp@abelian.demon.co.uk
To: tssp@abelian.demon.co.uk
Subject: Re: [TSSP] Ion Cloud Loading
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 <4.1.20020228184944.00a0ab40@pop.dnvr.qwest.net>
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Hi Paul,

I suddenly found as I walked out the door for work this morning that the
whole town was socked in with snow.  Weee!!  Snow Day!! :-))))

I think the output impedances of the TCT and Bertan really killed the Q of
the other test so I set it up differently.

I set up the secondary driven from the HP33120a (Zout = 50 ohms, I could
have used a low-z amp but I forgot) with the Tek3012 monitoring the signal
with the antenna as is normally done.  I set a second coil and terminal
next to the first and charged them up with the Bertan:

http://hot-streamer.com/TeslaCoils/Misc/IonCloudTest/NextTest.jpg

The center and -3dB frequencies are:
263.84kHz
262.00kHz
260.30kHz

Thus the Q is 74.86.  I set the signal to 9.00 volts (I must have moved
because it was 9.04 when I started the test) giving a resolution of 1 part
in 900.  I could detect the Fo frequency change 140Hz in this way or 1 part
in 1870.  So charging the right sphere up from 0 to 45 kVDC gave the
following shift in the received RMS signal.

kVDC		Voltage
0		9.04
5		9.04
10		9.04
15		9.04
20		9.04
25		9.04
30		9.04
35		9.04
40		9.04
45		9.04  (corona)

So having the coil close to a charged object seems to have no effect on the
Fo frequency.  If there is some tiny effect down there in the noise, it
would not be detectable in normal situations unless something goes wildly
non-linear at really high voltages.

>Oh, and while we're putting kV of DC into the coil base, would
>this give a nice and accurate method for estimating the total Cdc
>of the secondary?  Charge to a few kV, disconnect the Bertan, and
>then time the voltage decay as it leaks back to ground via a 
>known shunt resistance?

I don't think so.  Switching a few kV tends to be "messy" and corona
leakage may be a big factor.  There is no reason such a test would not work
just as well at only 5 volts were normal instruments and such are very
sensitive and capable.  I don't see any advantage of doing a discharge test
for capacitance over a more sensitive and easy LCR meter as long as the
sense signal's frequency was far away from the coil's Fo frequency.

Cheers,

	Terry


At 09:50 AM 3/1/2002 +0000, you wrote:
>Further to this,
>
>It occured to me that it might be better/safer to drive the
>coil from the TCT via a few well insulated primary turns,
>otherwise fine tuning could be nerve racking.
>
>Terry wrote:
>> I found no evidence that the coil's DC potential had any
>> affect on the system's resonant frequency
>
>Oh, I see now.  If fres varied, then you'd expect a lower
>amplitude. 
>
>> The "Q" of the coil setup was about 15.8 (253/16)
>
>So not a very sensitive test, I think.  How about repeating
>it with TCT into primary, freq counter, and a much smaller
>topload (so that the 'ion C' has a greater relative effect).
>
>Greg wrote:
>> I suspect that it's the additional capacitance of the streamer
>> channels themselves which are actually responsible for any
>> measured tuning shifts.
>
>And I'm guessing that Bert would concur.  The streamer channels,
>rather than a cloud of ionised gas molecules, would be the
>major source of an 'upheld' charge.
>
>Oh, and while we're putting kV of DC into the coil base, would
>this give a nice and accurate method for estimating the total Cdc
>of the secondary?  Charge to a few kV, disconnect the Bertan, and
>then time the voltage decay as it leaks back to ground via a 
>known shunt resistance?
>--
>Paul Nicholson,
>--