Vttc

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

Original poster: "James by way of Terry Fritz <teslalist-at-qwest-dot-net>" <mustang3-at-cox-dot-net>

Hi John,  list
     The vertical coil is powered off the 240. I have a 
<mailto:240V-at-28A>240V-at-28A variac that I use on the plate xmfr. Drawing 50A 
the toobs are very hot in a minute or so. So I let it run for a min or so 
and then off for a while. The plate cap is a big mica 
<mailto:.0056uF-at-10KV>.0056uF-at-10KV. It's current is rated at 
<mailto:9.1A-at-100KHz>9.1A-at-100KHz. The cap gets too hot on long runs. The 
tubes and cap get very hot if I feed the primary full-wave rectified DC or 
filtered DC. Filter is <mailto:1uF-at-8000V>1uF-at-8000V (usually a bunch of 
uwave caps in series and parallel). The bridge is 16 diodes in a string, 4 
strings in the full-wave bridge. The corona is dazzling on full-wave and 
has that 120 Hz rasp rather than the old 60Hz buzz. On 1/2 wave the tubes 
take several minutes to get bright orange. The primary is 15' in dia. with 
24T of 2 paralled #10 THHN wires. The tickler coil is the same diameter, 25 
T of #22 wire under the primary by 2" or so. The grid leak is a 
<mailto:.005uF-at-5000V>.005uF-at-5000V cap with an adjustable 
<mailto:5K-at-250W>5K-at-250W resistor as the gl resistor. The grounds are all 
carried to the power ground. I have a external ground rod for my SG coil, 
but have never hooked it to the toob coil.
     How tuning is a real pain for a tube coil. Since we're want the 
longest corona, we tune for that. It's a trial and error sort of thing. 
When you observe the coil with a spectrum analyzer, you notice something 
interesting. As you increase the plate voltage, the frequency goes down. I 
used WinTesla and the solenoid program to find ballpark values on 
frequency, cap size, etc. I use an oscope and a spec an to to these things.
                                                                                                        Later,
                                                                                                                James