Peter Dettmann wrote:
On Tue, 09 Oct 2007 15:07:36 -0500, Raymond Koonce
wrote:

Some photos of an unusual tube I got in a box full. It appears to be a
triode. The only numerical marking I can find indicates a Type 488. I
can't find any information on the usual spots on the web. I made a shot
from the front showing the mesh plate structure and a shot from the
top. I tested it in my tester as a 26 but with 6.3V on the filament and
it tested well in the "Good" zone. Testing as a 45 @ 6.3V on the
filament increased the purple glow and it still tested in the "Good"
zone. Does anybody know what this tube is?

Raymond

I assume that testing did not involve anything except emission, so
Alan may be right that it may be a diode.
But it seems from the photo that there may be a grid there?
Certainly it is gassy, so not really useable.

Peter Dettmann


Hi Peter,

I have some higher resolution photos and there is definitely a grid
visible behind the mesh. I assumed it to be a triode and gassy. It's
nice to look at anyway.

Raymond