PCL85/ ECL85 ratings

[CambridgeWorks]

Not wishing to hijack the current threads wirh PCL82, I started this one.
I was going to post on that one that I have some ECL85 currently offered on ukvrr, just in case any experimenters here might be interested
My reason for starting this is that just looking up the ECL85 on r type.org, I do not understand the pentode ratings,so clueless as to any audio amp suitability.
I can only assume that the anode being a lot lower voltage than screen and rated 200mA max is something to do with ffame output tv service rating?
The 6.3V current is also stated as 30mA, not 900mA.
Any ideas why these particular ratings given on r type.org?
http://www.r-type.org/exhib/aai0510.htm

Thanks,
Rob

[Mike Watterson]

The PCL85 is 300mA and the ECL85 is 900mA, reflecting 17.5V vs 6.3V

The anode being lower than screen volts is why the Pentode/Kinkless Tetrode/Beam Tetrode was invented, either having a 3rd suppressor grid or electrostatic plates connected to 0V or cathode. A pure tetrode has a kink or negative resistance region and originally called SG or Screen Grid tubes/valves, used for first RF stage or a mixer or an oscillator.

The r-type site seems to have put the PCL85 current.
https://www.radiomuseum.org/tubes/tube_ecl85.html
https://www.radiomuseum.org/tubes/tube_pcl85.html

The PCL85 seems to have been more common (and TV). Audio more often used ECL82, ECL86 or EL84. I can't imagine the ECL85 was used much for TV, so the r-type page seems edited from the PCL85. The PCL85 page seems correct http://www.r-type.org/exhib/aaa0382.htm

Some French TVs may have used the ECL85. Almost all the models I looked at with ECL85 in "popular" years seem to be TVs and mostly French. These would have had a massive 6.3V supply? https://www.radiomuseum.org/r/clarville_dx59dx_5.html and https://www.radiomuseum.org/r/ribet_603_...ffret.html

A rarer audio application of the ECL85 https://www.radiomuseum.org/r/bang_ampli...i_610.html

[Mike Watterson]

Very late Czech radio with ECL85
https://www.radiomuseum.org/r/tesla_lyra...327_a.html

Mostly ECL85 does seem to have been frame osc and vertical/frame drive in French TVs, the PCL85 being in series heater TVs.

[Mike Watterson]

The Va and Vg2 are both rated about 170V on some diagrams.

I imagine there are more mainstream audio valves with plenty of design examples. You'd be a bit on your own unless you found a schematic for the B&O, which is likely push-pull, so a centre tapped or dual winding mains transformer will work for audio out. Maybe 20W to 30W depending on class AB bias level for push pull if really 9 W Pa. I'd imagine it gets hot with 5.7W heater too.

[CambridgeWorks]

Mike, those Va, Vs make more sense. I realise the 0.3A was only the P series version.
Thanks, Rob