Start by identifying the pins. Usually just a little bit of deductive reasoning is all thats required.
See this article here as a guide: Identifying a Mystery Tube
See this article here as a guide: Identifying a Mystery Tube
Then you'll need to wire it up and check its characteristics. The process is simple.
Identify some candidate tubes.
Start with the filament to get its IV characteristic.
Then try some low level operating point checks.
Identify some candidate tubes.
Start with the filament to get its IV characteristic.
Then try some low level operating point checks.
No way,
this tube has a 6.3V 150mA indirect heater.
Tubes for hearing aids had 1.25V 25mA filaments or so ... and were DHT.
this tube has a 6.3V 150mA indirect heater.
Tubes for hearing aids had 1.25V 25mA filaments or so ... and were DHT.
I was not aware that the little tube had those heater characteristics, which would make it unsuitable for a hearing aid.
Believe it or not, but a Sovjet 6n16b has 6.3 V 400mA heater power, in the same envelope; the 6n16b is a dual triode with plate curves similar to 6SN7.
The tube in question - marked F511 - seems to be a 5840 pentode.
Pinout and characteristics match 5840 aka EF732 spot on.
Va = Vg2 = 100V / Vg1 = -1.5V --- Ia = 10 mA
Va = Vg2 = 100V / Vg1 = -2V --- Ia = 7 mA
Va = Vg2 = 100V / Vg1 = -2.5V --- Ia = 4 mA
The F511 marking is still a mystery though ...
Pinout and characteristics match 5840 aka EF732 spot on.
Va = Vg2 = 100V / Vg1 = -1.5V --- Ia = 10 mA
Va = Vg2 = 100V / Vg1 = -2V --- Ia = 7 mA
Va = Vg2 = 100V / Vg1 = -2.5V --- Ia = 4 mA
The F511 marking is still a mystery though ...
Most probably a part marking from either, what ever it came out of, or was intended to go into. Doesn't matter. Remark and move forward. Mystery solved.