>Impedance at 150 Hz (sine wave) using a signal generator with 50-ohm
>output: 1.0 Vrms --> ~25 mA so ~40 ohms.
>Impedance at 1000 Hz ditto: 1.0 Vrms --> ~9 mA so ~110 ohms.
>My generator couldn't maintain a square wave while driving the valve
>because of its higher output impedance (result was a set of spikes
>with smoothly declining tails) but the numbers at 150 Hz were similar.

To clarify...the voltage at the valve was 1.0 Vrms.  Voltage
indicated by the generator was much higher because of the high
generator impedance.

Yrs,
d