Lowest V at which damper diode tubes work

[dimkasta]

Does anyone have any info about what is the lowest V at which these tubes start conducting?

Do we have to push them hard or just get past their forward voltage drop?

I am mostly interested in 6CT3 and 6D22S families, and want to try them on low voltage and low current line level circuits (10 - 35V at a few 10ths of mA).

Thanks

PS
Please do not waste your energy suggesting a solid state bridge or diodes. It is what I am currently using.

I want to try tubes for various reasons, most of which are rather controversial

 

[Yvesm]

Hot cathode vacuum rectifier has no threshold voltage but has a serie resistor which diminishes with the forward voltage.
Look at here (last page):
https://frank.pocnet.net/sheets/030/p/PY88.pdf

Yves.
<edit>
Up to 50mA, the MUCH smaller 6AL5 can do the job without wasting watts just to light heater !
https://frank.pocnet.net/sheets/093/6/6AL5.pdf
</edit>

 

[DF96]

Most vacuum tubes start conducting with a small reverse voltage. Forward voltage then greatly increases the current. Have you looked at datasheets?

 

[DavinCarter]

I did not find a datasheet that has any sort of curves.
Vacuum diodes usually start conducting at 0 forward so there is no concern about minimum voltage.

Mercury vapor and xenon like the 3b28 have a starting voltage.
The 6CT3 and 6D22S should be OK at any voltage within reason.

 

[smoking-amp]

Vacuum diodes generally follow near the 3/2 power law. I = k V^1.5
Here is a graph for one:
https://frank.pocnet.net/sheets/127/6/6CD3.pdf

https://frank.pocnet.net/sheets/049/6/6CT3.pdf
For something like the 6CT3, which does not give a graph, there is typically a datum for one point on that curve. 6CT3: 350 mA @ 16V

So 350 mA = k 16^1.5
solve for k
For any other point: I = k V^1.5 or (I/k)^.6666 = V