18Watt.com

The 6p3s, no suffix, is usually a straight copy of the 6L6G and was supplied into Western markets by Brimar as the 6L6GT (T = straight envelope as opposed to "coke bottle"). Don't try to push them too hard and they work OK. After deep thought, I would say 12W is probably the limit, but I'm pushing my addled brain there.

Sounds like you're confusing 6V6 and 6L6 specs there. A clone of a 6L6GT should be good for 19W dissipation.

Not exactly - I'm thinking more along the lines of "it depends on the factory", and also of a B&O hifi amp I once had that ran 6L6 at 12W. There is always the possibility that a factory was making the lower-rated 6L6 with a glass envelope. The 6L6 / 6p3 was the original design, and had a metal envelope - I have never seen a russian one, but that is the design the US gave the Russians.

The 6L6GT and 6p3s I have seen were made in St Petersburg, and they are likely to work like you say, but some eBay sellers tend to use pictures as "illustrative" and send you anything they can get. The older the stuff they find, the more likely it is to have a lower power rating.

...and also of a B&O hifi amp I once had that ran 6L6 at 12W. ...

I would guess that was something they were doing to keep the valve running at maximum linearity and infinitesimally low THD. 12W is even low for a 6V6.

FWIW, one of the contributors at the ampage forum provided a little bit of further info on the 6P3S (if anyone else is curious about it). (He is a yankee now living in St Petersburg from what I gather):

http://music-electronics-forum.com/t242 ... post208036

6P3S are indeed close to 6L6 GT, are rated 20,5 watts, and i use some in A class under 330 volts and 96% max dssipation with no problem.