Anyone Tried Russian Miniature Pentodes?

[Yorkie]

There appears to be a growing interest in the dinky ex military wire-ended Russian pentode valves, not least I guess because not only are they small, but very cheap to buy, as in often well under £1.00 each. I've no idea what the differences in performance and suitabilty for making radios is as tere seems to be a wide range of types, with differing anode voltages, but most commonly they seem to have 1.2V heaters. They mostly seem to be sold in lots of ten, but you can have 50 for £21.00!

Here are a few links:

150V anode:

http://www.ebay.co.uk/itm/10x-1P24B-V-Ru...tronics_R2&hash=item2c6618155c

60V Anode:

http://www.ebay.co.uk/itm/10x-1J24B-1Zh2...tronics_R2&hash=item2ec555259c

120V anode:

http://www.ebay.co.uk/itm/8x-6P30B-Sovie...tronics_R2&hash=item2ec50153c4

50 for £21.00:

http://www.ebay.co.uk/itm/1J18B-1Zh18B-R...tronics_R2&hash=item2ebbbdb44b

Any thoughts anyone?

[Steve_P]

Modify the circuit and they might make reasonable replacement UL41's. 4 Watt Output. Surely we can find the heater volts from somewhere?

Cheers,

Steve P.

[Joe]

This seems pretty definitive but is way over my head: http://www.radiomuseum.org/forum/russian..._id=200277

- Joe

[Yorkie]

This seems pretty definitive but is way over my head: http://www.radiomuseum.org/forum/russian..._id=200277

- Joe

Thanks for that Joe - strewth, it went whoosh over my head too -looks like the basis for a PhD thesis! A bewildering assortment of types.

It certainly answers my initial query 'does anyone know about these little valves'? Given their very low price, I guess the surplus market must be awash with them. Nice 'pantry transmitter' potential, or funky little i-pod docking amplifier or what not? In the late 60s in Practical Wireless (when it was both 'practical' and about 'wireless' - not just an amateur radio mag), there was an article about converting NHS surplus 'Medresco' (Medical Research Company) miniature valve hearing aids, which used three tiny wire-ended valves. For a few years I used one that I adapted for use as a baby alarm - very sensitive.

[Joe]

Quite agree, David, but practical circuits seem thin on the ground.

- Joe

[John M0GLN]

I've not used any myself but this chap has used similar wire ended valves with apparently good results.

http://g4oep.atspace.com/xfy/xfy.htm

John

[Yorkie]

Thanks for reading the post John, and for pointing us to the link. Excellent website too, with lots of stuff worth looking at!

Take a look at the Phillips 'Superinductance' ('Ovaltiney') bought for a bargain price, but then - as in so many cases - the cabinet has been stripped and the two dark bands of toner, which look like a darker veneer but aren't. have been removed and the cabinet French polished, thus destroying its originality. I'm sure that in many cases, with the original lacquer flaking off, the 'restorer' starts to strip the cabinet, not appreciating that the two dark bands aren't - as he may have believed - a darker veneer, but dark toner. By the time that's realised, it's too late. Almost all of the Superinductances I've seen have been got at in this way. Shame really, given that the older and more classic the set, th3 more care it deserves, and the more important that 'conservation' rather than 'renovation' is called for. The set in question hasn't been 'restored' it's been modified, and thus, downgraded in a very noticable way.

I wonder if these sets ever find their way into the hands of top class restorers rather than enthusistic dabblers?

http://g4oep.atspace.com/oval/634.htm

Right off the topic of minuature valves, but relvant neverthess to the website in question.

[Refugee]

I have already grabbed one web link for these.
What I intend to do is to create a preamp for a modern magnetic gram cartridge so that i can use a posh turntable with a pair of very nice 25W valve amplifiers like the one in my avatar.
This is being held up by lack of a circuit diagram for the amplifiers taking up time to reverse engineer one to create my own circuit diagram.
I have an audio source in the form of a modified music center and would like to go for the next generation of my creation.
I do not need to modify these amplifiers as there is a jack socket on each one that all my bits plug into.
I will be starting a new thread in a week or so for my project and have been collecting know how from the only place I know there is a small number of practical circuits. I will have to re-engineer one of these for a start.