Russian rod pentode circuits

[Jez]

Nuvistors are virtually the holy grail of valves for a start! Absolutely superb for many of my applications. getting the sockets is an issue though.

I reckon 1ж24б  and 1ж29б -в then plus there's a few others I've been meaning to get for a while such as some 6с17к-в and 6ж52п so I'll have to search for a store that has all and can combine the postage.

Prices seem to vary considerably and delivery time up to 3 months! all looks a little dodgy....

Добрий вечір

Although I have not used any yet, apart from a few tests, the Russian Nuvistors I bought have long leads so can more readily be used directly. I have to say though they follow the usual Russian practice with leaded valves in having them all over the place (although it does follow the specification) so it does take some deduction to determine which lead is which. A not uncommon trait is to have a lead shown on the diagram but is actually cut off on the base, although I cannot remember if that was the case with these.

I have bought some valves from the Ukraine since the war started but I decided to track down a supplier away from the front line. Some appear to be within a few miles of the strife. The supplier I used was in Odessa and the valves were delivered promptly (I remember not how long but maybe 1 to 2 weeks). This was Just before the Russians started targetting the grain silos in Odessa but I think you would be unlucky to get poor service.

Russia is obviously out of bounds and the only ones I have seen from there, which appear to have been stopped when I last looked, were routed through China.

Prices seem to have increased, as might be expected, but the best I have seen seem to be from the Ukraine. Sellers do seem to keep an eye on the market though.

Tracy

Ah yes I do recall seeing pics of Russian Nuvistors with flying leads. The RCA ones that need socketing also have many leads cut off flush on the bottom as they form the structural support for the electrodes internally but not all are needed for connection to external circuitry. The RCA ones can have very low noise and microphonics which suits the audio work I do.

I had a quick google for possible sources the other day and in fact the two most prominent search returns (for rod pentodes and other types) were for Russian suppliers and they were offering them for 72p each which is about what I was expecting having briefly googled them maybe 6 years ago and before I had learned any more about them here of course. There are obvious ethical problems with buying from Russia and then the issues likely over banking sanctions etc so I always intended to try and get them from Ukraine of course. Ukrainian and Bulgarian suppliers seem to be only on ebay, not sure if that's good or bad! Probably puts prices up but gives a little more peace of mind I guess.

It is all a bit confusing though as they have very much gone up in price from ebay, £1.50 - £2.95 each from what I can see and some suppliers seem to have listings for £1.50 ones and for £2.95 ones with the same descriptions and they look the same in the photos.... also there are several potential ebay shops for them and having never imported valves from Eastern Europe, never mind during a war, I don't know if a specific supplier is one of the good ones or not....
I'm probably a bit paranoid but another worry is that if ordering say £60+ worth of various valves to keep postage down then it's not as if I could go and bang on the door of the supplier if I never receive them!

Ideally I want to find a supplier that is both trusted and has all the valves I want. The 6C17K-B (in Cyrillic. I prefer Cyrillic for such valves as there can be a few interpretations of Cyrillic lettering and mistakes in translation can also occur) is interesting for a start. A disk seal planar frame grid triode for UHF/low microwave frequencies, I believe directly heated but not sure from descriptions if they mean indirectly heated but cathode and heater are connected, around 22mA/V Gm and Mu of around 180 with reputedly zero microphonics. Very small. Connecting them to anything could be fun... hoping soldering directly to the ring terminals would work, and avoiding them taking off at say 1GHz may be a problem. Only about £2 each though and promise very low noise for low level audio amplification. I have seen them put to this use in a few places on the internet so not my idea no. I saw some on ebay from a Bulgarian or Romanian supplier that were only something like £8 for 12 (but around £11 delivery!) but although described as new they appear to come without boxes (not sure on that) and appear rather "dirty" but I think that could just be blackening of oxidising silver as all the "terminals" are silver plated. The £2 ones from Ukraine have boxes and look shiny.

If anyone has specific recommendations for suppliers that can be trusted that would be great.

(must re-read Mark's post about quoting!)