8BQ5

[boots]

I ended up with a couple 8BQ5's from a box of junk I picked up at a salvage yard. I found a few good tubes I can use, but I don't want to mess with the 8BQ5's.

They are identical to a 6BQ5 (aka EL84!!!) except they have an 8 volt filament.

Anybody want them? Free for the taking. They are not tested, but I could probably pop them in a SE EL84 amp briefly to see if they are functional. I have 2 in my hand and I think a couple more somewhere.

I have a growing collection of other oddball tubes too, so let me know if there is something in particular you need. I hate to send them to the dumpster, but they are starting to take up too much space.

[Leo_Gnardo]

I could probably pop them in a SE EL84 amp briefly to see if they are functional.

Try it, you might like it. "Browned down" EL84's, could be just the thing.

A cheap experiment that might produce a useful result. I'm sure not the only one who would like to hear what happens if you give 'em a go.

[martin manning]

Running at 6.3 or maybe a bit more they will be ~80% of spec voltage, and probably work fine. Experiments I ran with the uTracer back that up.
https://tubeamparchive.com/viewtopic.ph ... 104#337104

[boots]

Do you think running tubes on lower than spec filament voltage would promote cathode stripping?

[martin manning]

Someone here ran an experiment using low filament voltage as a volume control, running them at around 2V for a couple of days straight with no adverse effect.

[Phil_S]

Here: http://www.ebay.com/itm/NEW-HAMMOND-160 ... SwrklVYNNV Git to work!

[martin manning]

No good Phil... The 8BQ5 heater needs 600 mA, so that means 4.8 VA for each one.

[Phil_S]

Eeeks! I thought it said 4A, not 4VA! Sorry ;-/

[boots]

The 8BQ5 works OK in place of a 6BQ5. Seems to break up pretty early compared to the 6BQ5 though. That would be expected.

I have a good stash of sweet EL84's here, and will probably never mess with these 8BQ5's. So if anybody wants them....

One is a Tung Sol and is a little noisier than I like, but sounds great. The other looks like a Sylvania but says WE (Western Electric?). It was very quiet, but not quite as much output as the TS.

Up for grabs.

[shoggoth]

[self-deleted]

[Phil_S]

I've got a 48V PT that would be perfect for a sextet of 8BQ5's. Anyone want it? (It's heavy.)