Martin Damev:Re: [TCML] Sloans high power VTTC

["Martin Damev" <mdamev@xxxxxxxxxx>]

Hi Folks,

Unfortunately Sloan's circuit described in the Phys. Rev. No. 47, 1935
isn't well suited for VTTC purposes.
A resonance transformer as described by Sloan works well as long as
the ohmic load parallel to the secondary resonant circuit (Rp) is high 
compared
to the impedance of the secondary circuit, resulting in a high Q (for 
example Q>30).
In a VTTC the ohmic and capacitive loading of the secondary circuit by the
spark is substantial, therefore with the spark growing the Qsec. drops and 
the
resonant frequency drops. This fact necessitates the used of a tuned 
resonant primary
circuit in order to obtain a useful impedance matching and energy transfer.
Sloan's circuit has only ONE resonance circuit, the secondary helix. The 
primary circuit
is not resonating at the same frequency.
Several years ago i did calculations based on Sloans resonance transformer 
circuit and I
built a test circuit using a power triode (Anode dissipation: 3.5kW). The 
results were
absolutely disappointing. Since I followed Sloan's principle of not having a 
tuned primary circuit
the oscillator always shifted to parasitic oscillations in the MHz-range 
instead of oscillating
around 150 kHz. In other words: It was unstable and the efficiency low. 
Reducing harmonics
by increasing anode conduction angle didn't really help. Performance was 
very poor (8 inch spark with
5 kVA apparent power at the HV-transformer input).

IMHO it is necessary to use a tuned primary circuit with self-excited tesla 
tube coils.

Concerning large RF power sources using vacuum tubes, the largest industrial 
RF generator I know,
was a 1000kW-induction oven built by the Swiss company BBC (Brown Boveri) 
using three BTS150-2
high power triodes.

-Martin












Martin Damev



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