EL300 = 6FN5 / PL300 = 35FN5 tube

[hidnplayr]

Anybody here knows this tube, or better yet, has used it in audio?

datasheet: http://www.mif.pg.gda.pl/homepages/frank/sheets/020/6/6FN5.pdf (in french)

 

[Kay Pirinha]

Hi,

as for all TV sweep tubes I suspect poor performance when considering single-ended class A mode. However, push-pull should work.

 

[Yvesm]

Some make amazing triodes . . .

 

[hidnplayr]

Some make amazing triodes . . .

Exactly what i'd like to find out..

 

[Yvesm]

Unfortunatly I've no curves available for this tube.
Just look at one of its cousins: EL/PL36
Not worst than a 2A3, no need for DC heater and a bit easier to drive

Yves.

 

[hidnplayr]

Yes, I am familiar with the PL36
Is it possible to create the triode curves from the pentode curves?
Or is the only accurate method to measure them?

 

[Yvesm]

The data sheet does not tell anything above 200 Vanode and only for 3 screen values, I fear that extrapolation be very approximate !

If you aren't lazy, 2 adjustable power supplies and 3 DVM is just what you need to measure . . . along with pen and paper . . . or a calc sheet

 

[hidnplayr]

Ok I measured the characteristics with my scope (with individual grid settings)
Now I need to combine those characteristics into one, I could use excel, but maybe you know a better program for this?

 

[hidnplayr]

Tadaaa!

Left most curve is 0V, from there on i used 5V increments.
Dissipation curve drawn is for 22,6 W (17,6+5) but I believe this tube can handle some more...

Now how do I calculate mu, rp, ideal plate load etc?

 

[Yvesm]

Hey, you're going fast ! !
Do you have some numeric series as f.e.
Ua, Ia, Vg
50, 80,0
100, 270, 0
150, 480, 0
. . .
50, 10, -10
100, 75, -10
etc ... (values roughly estimated from your picture)

?

 

[hidnplayr]

It was indeed a quick measurement and very rough, but it should be good enough to find some things out..

Here is the excel file: