Russian rod pentode circuits

[Mike Watterson]

So is there actually a 1ж24п or this a typo and 1ж24б what was meant? I see references to both, plus Mike saying to avoid the  1ж24п as "it's a monster", but elsewhere I see someone admitting it was a typo when they wrote of 1ж24п. I can't find a datasheet etc for 1ж24п and only maybe half a dozen mentions of it on google, all in Russian.

To be clear, my interests are for mains powering them, including the heaters, and size, power consumption etc is N/A.

…
what I really want to experiment with is whether or not the somewhat odd characteristics of the rod pentodes could be put to use for hi fi pre amplifiers, microphone amps and phono stages etc. ie may they, under the right conditions, give markedly less distortion and or lower noise than conventional valves.

Yes, you can use a 1.2V DC supply and multiple HT rails from 45V to 200V depending on model from the mains.
All amps need some negative feedback to be linear. The Rod pentodes have no "real" grids, being electrostatically focused beams, so very very low noise. They are inherently sharp cut-off and fairly linear, so pentode designs like for EF80 or EL84 will work. The g2 can be tied to anode for a more triode like performance, but unlike real pentodes the g3 must be tied to 0V, f- or f+ or some LT voltage. Note that Beam Tetrodes and Kinkless Tetrode are more like pentodes, and really the g3 "beam plates" is electrostatic rather traditional grid like an EF50 or EF80.

1ж24n is Cyrillic. Transliterates to 1j24p. The ж is also transliterated to sh and zh as well as j.
But a typo. Should be 1p24b, or 1П24Б
My mistake earlier. It's been a few years!
Data Radiomuseum 1p24b-v
The suffixes are variations of robustness.

Really unless you want batteries an EL8x is better choice than a 1p24b.

And for mains powered audio the EF86 for preamps. EF80 (common as muck) everywhere else. You can maybe get 500mW+ audio on an EF80, and you can use them as triodes, or maybe 2W class B push-pull.

Another good mains valve is ECH81 / ECH83 (often the same valve marked differently). It, ECC82, EF89 and some others will work at 11V to 14V HT. While the ECH81/ECH83 has a common cathode it can be used as a separate pentode (just fixed biased Hexode) and triode. Thus an ECH81 can be Pentode preamp and triode phase splitter. It also can do moderate listenable power direct.

There is almost no point to using the Rod Pentodes on mains only, apart from the monster 1p24b, but many mains valves make more sense. The 1p family was mostly used in short life proximity fuse and earlier versions in some early satellites inc actual sputnik. I have a bunch of 1p24b, but only for testing. I think pointless. I have many of most Rod Pentodes. I also think the 1j37b is only of historic interest. A PIN diode is a better variable gain (and an 1N4007 works at HF!), and plenty of better mixers.

Hence I only bought more 1j24p and 1j29b. The 1p2x other than 1p24b are just older models.
The 1j17b is very old, replaced by 1j18p, replaced by 1j24b.

Main Radio Museum thread and list of known types with links to data

See also https://www.radiomuseum.org/forum/rod_tu..._1960.html Link to translated PDF

I got a couple of 1j42a to test, but can't imagine making anything with them.

The last one to be found AFAIK is the EM10, electrometer valve. Seller is in Ukraine.
Seller also has miniaturised versions of the 6.3V indirect filament valves close to Rod Pentode appearance. Also there are EMxx series miniature Electrometer valves that are not Rod Pentodes. I have a Russian schematic of an Electrometer maybe using the 1j42a and 1j24b, not sure.

I also have the USA/UK sub-miniature vavles used in military, hearing aids and some japanese pocket radios (unless earphone only, they used like a DL91 or similar B7G for audio out). They are inferior to the rod pentodes, though there is a triode-pentode mixer. I have some NOS nuvistors which were a crazy idea. Only widespread consumer use was VHF tuner-heads in mains equipment. Too expensive. Quickly replaced by VHF Germanium and then Silicon.