Anybody use the QB5/1750 as a modulator tube

[KM1H]

Its the size and base/socket of a 4-1000A but a bit similar to a 4-500A that isnt as fussy about airflow.

I just picked up a new pair of 90's production for next to nothing and Philips has some info on modulator use (4000/5000V only) but call it Class B even tho the idle current looks pure AB2.

Id like to run at around 2500-3000V as I dont need 2KW of audio and a sky high PP load.

Carl

[KM1H]

What...nobody has used them.

Timtron told me on 75 a few days ago that he had bad experience with reliability at RF but thought they should do OK at audio, especially at reduced levels.

Here is a size comparison between a PL-175A (4-400A sub) and a 4PR1000A.

[John K5PRO]

I guess not. Reckon you're on your own with those bottles. Let us know how they work out.