Tom Schlangen wrote:

Gentlemen,

ECL86/6GW8 or PCL86/14GW8 pentode section triode strapped data now
is available he

http://www.tubes.mynetcologne.de/roe..._as_triode.pdf

As usual, three samples (Mullard 6GW8, ITT/SEL mil spec PCL86,
EI PCL86) were measured and the data was averaged.

Thanks Tom.

The Ra = 2.5k at Ia = 30 ma, Ea = +300v,
u = 14.3, so gm = 5.72 mA/V.

( 6BQ5 triode u = 20, Ra slightly less.)

1/2 12AX7 are not regarded as good triodes any more these days for
power amps but they work OK in these tubes in a circuit like the one at
http://www.turneraudio.com.au/htmlwe...0ulabinteg.htm

Patrick Turner.





While ECL86 gets scarce nowadays, the 300mA heater versions
PCL86/14GW8 still are plenty and cheap, even from "top" brands.

The triode section of this tube is exactly 1/2 of ECC82/12AX7
(nitpickers will say 1/2 of ECC808, with even better data).

The triode strapped pentode section is very linear, it is almost
identical to triode strapped EL84/6BQ5, except that the allowed Pd
is a bit lower (9 watts instead of 12).

Like triode strapped EL84/6BQ5, the trioded pentode section of this
tube will make a bombastic SE driver stage or PP "power LTP"
splitter/driver stage.

Two of them will make a complete front end even for the most swing
demanding PP output tubes: For example use the triode sections as
a diff amp input/splitter stage, and the trioded pentodes as sort
of diff amp / driver like the third stage in the Williamson.

The combined gain of the sections is very high (expect easily up to,
say, 500 times in real world apps). Thus take care to prevent
parasitic oscillations ...

Here is a tip I got from an old HAM: Have a close look how the
sections are wired to the base pins and you will see, that using
a very tiny earthed metal sheet at the socket at the right place,
acting as a static shield, would .... ;-)

Tom

--
When in doubt, use brute force.
- Ken Thompson