05-11-2018, 01:17 PM
(02-11-2018, 12:18 PM)Murphyv310 Wrote: A bag of worms then!!!
From what I've read the PL84 characteristics were taken as the HT available is less in AC/DC TV sets and that is the raison d'être for designing them in the first place. I'd suggest cutting open both types and do a comparison perhaps something will be gleaned that way. Thing is there are a number of references to say they are the same bar the heater.
My highlighting!
It's a bit drastic. One comparison tip (not my idea regrettably), is compare inter-electrode capacitances. If they are the same, then internal structure is likely to be the same. If the internal structure is different - closer grid/cathode spacing, finer pitch screen-grid, etc - then capacitances will change too.
My understanding is that UL84 = PL84 (apart from heater) and they really were designed to work well with a lower voltage HT so are genuinely different from EL84. nThe 6.3V counterpart is EL86
Differing heater 'letter' but same rest-of-the-type-number is an unreliable guide really. Counter-examples are abundant. DF91 and EF91. Or how about DM71 and EM71 where they are not even on the same base!
