09-09-2021, 12:22 AM
Thanks for the information Trevor, the comparison between the types is interesting.
I'm actually very surprised at your comments about the rod pentode being microphonic I have found them quite good in that respect, though at massive gain even the interconnections in a circuit can become microphonic.
Tracy... Yeah, I see your point about the valves working on beam principles, I have planned a comparison, I have one or two subminiature RF pentodes (straight) that I want to try as comparison with the Ruskies...
I did try their, (1j24b), sensitivity to an external magnetic field: it did not seem to work as an introduction of signal, also bringing a tiny bar magnet near it stopped it working completely, I'm assuming that the rods are nickel, and became magnetised, as I had to put a coil of wire onto my old solder gun and degauss the valve to get it working again... I could see how it could work if I'd found a way to sensibly introduce the field but it could only be AC and low frequencies, as they seem to retain magnetism...
I'm actually very surprised at your comments about the rod pentode being microphonic I have found them quite good in that respect, though at massive gain even the interconnections in a circuit can become microphonic.
Tracy... Yeah, I see your point about the valves working on beam principles, I have planned a comparison, I have one or two subminiature RF pentodes (straight) that I want to try as comparison with the Ruskies...
I did try their, (1j24b), sensitivity to an external magnetic field: it did not seem to work as an introduction of signal, also bringing a tiny bar magnet near it stopped it working completely, I'm assuming that the rods are nickel, and became magnetised, as I had to put a coil of wire onto my old solder gun and degauss the valve to get it working again... I could see how it could work if I'd found a way to sensibly introduce the field but it could only be AC and low frequencies, as they seem to retain magnetism...
