[Amps] tetrode reverse screen grid current,

[Roger Parsons]

I would be most interested to see what circuitry Racal came up with.

In the early 1970s I was responsible for the maintenance of a number a TA184 10kW auto-tune HF 

transmitters. These used a 4CX10000D with 7500V on the plate and 1200V on the screen, driven 

by a 4CX350A which used the 1200V for its plate supply (all IIRC!). One of them had a plate to 

screen short at one point, and whatever circuitry they employed did not work. The 7.5kV took 

out literally everything on the 1200V rail including the driver stage, power supply and associated 

circuitry. The transmitter was not quite a write-off but it took weeks and weeks to get it operational again.
I was never involved with the TA1800 and any later designs but presumably they were better.


73 Roger
VE3ZI