OS70/1750 datasheets

[chipie]

I'm searching for the data sheets of the Tungsram OS70/1750 tube. It's said they are equivalent with the 828 but I questioned that because filament of the OS70/1750 is rated at 7,5 Volt 2,5 Amperes (radiomeseum.org) while the 828 is rated at 10 V 3,25 A.
I searched the internet but could not find a data sheet for the Tungsram.

[tricomp]

FWIW,

This : http://frank.pocnet.net/short/054/4/441.pdf and the attached.

rgds,

/tri-comp

P.S.
You'll have to be able to understand a little Italian

[FullRangeMan]

Frank Tube datasheet database are offline now, nut you can search later:
http://www.mif.pg.gda.pl/homepages/frank/vs.html


OS70: http://frank.pocnet.net/short/054/4/441.pdf

[FullRangeMan]

Frank is online again:

http://www.mif.pg.gda.pl/homepages/f.../049/8/828.pdf

[tricomp]

I promise you that you didn't see this before.
This is a page from the 1941, July issue of OZ, the Danish Magazine for Radioamateurs.
What is says about OS70/1750 is basically:

OS70/1750 is a modern universal Pentode for work as a modulator or TX tube until 4 meter (~70MHz) with a high efficiency.
2 tubes in Class AB1, Push-Pull yields 300W LF-output and by applying NFB the distortionfactor can be kept below 1%.

No curves, sorry

rgds,

/tri-comp

[chipie]

Thx Tricomp, you also answered my next question for curves. Yes I'm planning to build a PP with those tubes. I would like triode connected but no triode curves to be found. So penthode connected is what is done in the schematics I saw till now ( STC 250 watt ) but I would like to do ultra-lineair with a 43% tap. BTW 300 Watt I don't need at all.
To get back on my original question, the OS70/1750 is equivalent with the 828 only filament is 7,5 V 2,5 A. Looks like Tungsram did a better job for getting the tube into emission than the RCA peepz.
Btw put the schematic with the post. It can be found at Dennis Grimwoods site Tubes

[tricomp]

Data found in old Czechoslovakian tube manual (Russian language)
Please note filament-data!
Still no curves.

rgds,

tri-comp

[chipie]

Thx Tricomp, at least that clears out the filament question. So radiomuseum.org puts the wrong filament voltage and current.
For the 828 are some curves but not specifically for audio use, seems to me it will get an experimental project