heater voltages PCL86 types

[bikerhifinut]

I have the bits to make a push-pull amp using ECL82/ECL86 type valves.

I'll forget using ECL86 as they are rare and expensive now, but I can buy 10 x PCL86 brand new and tested for £20 including postage. It seems churlish not to give these old telly valves a new lease of life!
As I will have to use a separate heater transformer anyway due to the mains transformer not having a sufficiently rated Heater winding I wondered if my spare 2 x 12V @ 1A per secondary would be ok on PCL86 as according to Duncan amps data page the PCL86 needs 13.3V @300mA. I could of course knock up a Constant current source with a 317 regulator but that seems to be complicating things and it'd be just as easy to get a 15V transformer and feed the PCL86's with regulated DC from an LM317 which should be ok to deliver the 1.2amps for 4 300mA heaters and if I needed a preamp valve then a bit of ohms law and a resistor would drop the voltage to 12.6V for a 150mA ECC81/83.
So the question is, would I get away with 12V on the PCL86 heaters, especially as the transformer has a 230V primary which would probably get me another volt?
Yeah I know I am being a cheapskate but I hate to see stuff in the toybox not being used.

Andy.

[John Caswell]

Hi Andy,
Well 12V just comes on the ±10% limit manufacturers suggest as norm.
As you have a 230V primary on the tx and it will probably be operating on say 245V, then that is roughly +7% just try it and see it certainly will not harm.
You will probably find that with all the heaters connected you won't have to do any adjustment for the ECC** heaters. Worth a try.

John