On May 9, 3:03*pm, "N9WOS" wrote:
A subject that has been getting under my skin recently.

The proper name for specific tubes

It seems that people, even the manufacturers can not figure out exactly what
type of tube they own, are selling, or even producing. You have various
people call the exact same tube all of the above (Beam power tetrode, beam
power pentode, or pentode). You have manufacturer data sheets calling it
something that on actual inspection, it is not.

For example. The tubes..

6AG5

6AH6

6BC6

6CB6

6GM6

6BZ6

...(on and on)..

Second section of..

6AM8

6GH8

6U8

All of them have an electrode structure that upon close inspection that
looks like/is a beam power tetrode. But the sales pages, and even the
datasheets call it a pentode. The datasheets show it with a suppressor grid,
where it actually has beam forming plates. What gives?.

Yeah, I was surprised when I first noticed this. Little TV IF tubes
with beam forming plates! And always drawn as a pentode and called a
pentode. Maybe somebody will make a headphone amp with 6CB6s and call
them beam power tubes.

You have a few people that have determined what they actually are by direct
visual inspection, and actually call them what they are, but that is few and
far between.

Is it just that the curves are close to a pentode, so the manufacturers are
trying to avoid confusion to the average end user?

Well to me, a pentode is just a tube with 5 elements. Cathode, plate
and three something-elses. Historically those were three grids, but I
don't know why the 3rd element has to be a grid.

And as far as people calling them beam power pentode, unless they actually
have three grids, and beam forming plates, then I don't consider it to be a
beam power pentode.

I think the descriptor "beam power" is similar to "sharp cutoff" or
"remote cutoff". A remote cutoff pentode isn't a pentode with an
extra element, but a pentode about which the description gives
additional information. Same with beam power pentode. But "beam
power tetrode" is much more common. So just listen up to the "beam"
word and then ignore the rest.

Is it just a big international conspiracy to confuse me?

Hadn't thought about that before, but I think you're probably
right.