High Voltage Heater info

[mashaffer]

I am intriqued by high voltage heaters. Does anyone know of some good sites for information on different tubes with heaters running on a couple dozen volts or more? Would be interesting to see how various tubes compare to the more common low voltage heated types.

mike

 

[jnb]

As far as I know they are otherwise the same and were made that way for specific matters of convenience.

One benefit I could see is that a larger portion of the heater would be more positive than the cathode in grounded heater applications thereby improving heater supply rejection.

For those of us that float our heaters for this reason, it may actually make it slightly more critical when keeping within Vh-k limits.

 

[mashaffer]

I would think that the lower heater currents would also make induced hum easier to avoid. My thought is for AC heater drive from seperate transformer.

There is probably a lot of NOS for many of these tubes available but I doubt that there is any current production which could be a problem in the future.

mike