Quote:
Originally Posted by ValvoStef
probably designed for EL84.
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In that case you'd expect the primary-impedance to be around 5K-Ohm.
A PCL86 in class-A, single-ended mode will need around twice that.
Two in parallel would be perfect for the transformer you've used.
If your high-voltage power-supply is up to it and you check that the screen-grid voltage is not sagging because of the second valve (reduce series resistor value or give each valve it's own), you should be expecting a neat rise in output power.
My guess would be output around 7-8Watt, obviously depending on what anode-supply voltage you are feeding the output pentodes. 300V should be the absolute max. if you want a reasonable long life from the valves. (Something the ECL86 variant ISN'T known to have in any case, possibly because it was usually run HOT and to the limit in many sets.) The ECL86 will easily develop Grid-1 current causing runaway cathode-current. I really don't know if that the case with the PCL86 as I don't have much experience with these. There should be no other difference than the filament configuration but who knows..?
Rgds,
/Torben
Edit:
Re. HOT and to the limit, see the attached.