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