Picture of the all-glass p-type socket tube in an article titled “Eenige eigenschappen van ontvanglampen bij korte golven,” by C.J. Bakker, Philips Technical Review, June 1936, pp 171-177
These very rare all-glass p-socket tubes are owned by Adri de Keijzer. He bought them in an open air booth-sale some 15 years ago. The pentode has a dark anode, the anode of the heptode is reflective (nickel?). There is no bottom view of the heptode because the glass is not transparent enough. The top grid connection has a diameter of 6.4 mm in contrast to the 9 mm which was used for normal p-type socket tubes.
Picture of the all-glass p-type socket tube in an article titled “Eenige eigenschappen van ontvanglampen bij korte golven,” by C.J. Bakker, Philips Technical Review, June 1936, pp 171-177
Heptode tube
Heptode tube
Pentode tube
Pentode tube
Pentode tube