QB3/200 seems to be more or less the same as a 4-65A:
https://tubedata.altanatubes.com.br/sheets/030/q/QB3-200.pdf
I can't see anywhere in the datasheet a recommendation running theses tubes at cherry red plate, but I can't see the usual flash getter on the tubes.
From the Philips DS, there is an example of LF amplification at only 600V / 30mA per tube: 18W plate dissipation at idle.
When looking at Eimac DS:
But there are operating points like 1000V / 60mA (for 2 tubes) so 30W at idle.
I suppose there won't be any red glow at the plate, from 18W to 30W, right ?
Do you know if it is mandatory to run these tubes at cherry red plate glow? if so, why did they provide these operating examples?
Thank you
https://tubedata.altanatubes.com.br/sheets/030/q/QB3-200.pdf
I can't see anywhere in the datasheet a recommendation running theses tubes at cherry red plate, but I can't see the usual flash getter on the tubes.
From the Philips DS, there is an example of LF amplification at only 600V / 30mA per tube: 18W plate dissipation at idle.
When looking at Eimac DS:
But there are operating points like 1000V / 60mA (for 2 tubes) so 30W at idle.
I suppose there won't be any red glow at the plate, from 18W to 30W, right ?
Do you know if it is mandatory to run these tubes at cherry red plate glow? if so, why did they provide these operating examples?
Thank you
It does appear that these QB3/200 tubes are very similar to Eimac's 4-65A. But these have a thicker graphite anode as quite a few European industrial equivalents have. The thin zirconium plated tantalum plates are the type that will glow cherry red. The graphite types do not get bright red. They may run a barely precipitable dull red at maximum plate dissapation in a darkened room, but you should not force them to glow red like their thin plate counterparts.