[Techlunch] Winners and loosers
Thu, 06 Dec 2001 09:33:17 +1100
Was that OUR Gilbert Hughes that won box office tickets to the PM 11 cricket?
I take it that you all have heard that Wally & Meredith have tied the knot after a
few years of compatibility testing? If knot, you have now!
Technical Problem Bit:
We at the ANU have a HyForce 30kW RF Heater. Self oscillating magnetically
focused triode (STC 3RM-245G) running about 350kHz determined by tank + load L.
The normal idling parameters are 7.5kV HT @ 2A, up to 7A @ full power.
Power is controlled by +ve DC on grid, shunted via transistors to reduce power.
At idle, it has 0V DC on the grid, at full O/P approx 650V,
Problem is that it can no longer reach full output (IP = 2.4A max) and at idle IP = ~0.5A.
Grid current is a little higher than usual (75mA), grid DC control volts appear ~ normal.
How con one PROVE without substitution, that the very expensive valve has actually
gone soft, which I suspect it has?
Failing that, any other explanation of the operational phenomena would be welcome!
(Not much experience at this end).
I take it tha
Dennis Gibson, Electronics Unit
Research School of Physical Sciences & Engineering
Australian National University, Canberra, ACT 0200
Ph: (02) 6125 2607 [Intl: +61 2 6125 2607]
Fx: (02) 6125 4433 [Intl: +61 2 6125 4433]