26-05-2017, 01:16 PM
(25-05-2017, 09:43 PM)signalman4 Wrote: ... but has a ECC84 and a ECF80 rather than the P range used in TV tuners ...
That is because Jason used a parallel heater supply with 6.3V valves (E = 6.3V) whereas it was easier for TV designers to have a series heater chain across the mains, so all the valves had to be made to pass the same current - in this case 300mA (P = 300mA).
Some of the heater voltages in these heater chains were correspondingly high as greater power was required in timebases and so on.
A full breakdown of the ECF80 code is:
E = 6.3V heater
C = triode
F = pentode
80 = B9A base
You can find full details of the numbering system at:
https://en.wikipedia.org/wiki/Mullard%E2...esignation
