20-06-2020, 09:40 AM
(This post was last modified: 20-06-2020, 09:41 AM by Mike Watterson.)
Actually the P8 and Octal bases are only nearly the same. The m pin and f- are swapped as are f+ and the usually no connection on direct valves, or cathode on indirect.
So it's possible to mess up swapping. The Pinch leadouts are the same, though normally f- and "m" would be shorted at the base.
Later many octal use a button base, but the P8 long gone then.
Also later most signal valves use an outer mesh tube or solid tube as an internally fitted screen to the m pin or f- or g3 or cathode, thus removing the need for metallising.
So it's possible to mess up swapping. The Pinch leadouts are the same, though normally f- and "m" would be shorted at the base.
Later many octal use a button base, but the P8 long gone then.
Also later most signal valves use an outer mesh tube or solid tube as an internally fitted screen to the m pin or f- or g3 or cathode, thus removing the need for metallising.
