[ARC5] 3A5 Filament Voltage Question

[neilb at ihug.co.nz]

> The filament on the 3A5 is parallel wired.
>
> The spec sheet says 1.4 VDC, Max. A current alkaline battery will put out
> significantly more than that.
>
> I want to run the thing off an adjustable DC supply, and allow some 
> margin.
>
> Does anyone know roughly what the minimum DC filament voltage to apply for
> enough emission to work reasonably well? I just want to test the operating
> frequency and get a rough idea of the modulation deviation.
>
> Thanks,
>
> -John

Is your problem how to obtain 1.2 - 1.4 VDC from a power supply?
What about two 1N4007's in series, fed from a dropping resistor?
About 1.2 - 1.3 volts will appear across them, and this voltage will
remain constant, much like a zener diode circuit.

Sorry if I've misinterpreted your question. I found it difficult to see
what you're driving at.

73 de Neil ZL1ANM