1J26A Rod Pentode

[Murphyv310]

Thanks Michael.
Those links are very interesting.

[BusyBee]

Thanks for the updates Michael.

Tracy

[Murphyv310]

Hi.
The valves arrived today. It might be a week or two before I get the chance to do anything with them though.

[Kalee20]

Look forward to your results, Trevor!

[Murphyv310]

Hi.
The main issue is lack of info including the pinout.
The filament is 130ma @1.4v, likely to be a hot running little valve. No doubt it can be under-run for longer life. So I'll need to get details before doing anything.

[Murphyv310]

Hi.
After a lot of searching including the pinout on the original sale I'm no further forward.
The pinout on the Russian sellers page is for the 1j36b not the 1j26a
The 36 has a centre tapped filament whereas the 26 doesn't, the filament pins are not adjacent with one other connection in between, there are 7 altogether suggesting all electrodes and the screen are available.
I'll dig out the microscope and see if I can identify the connections in that way, although I'm not that confident.

[Mike Watterson]

It's not listed in the copy of Berg I have.

1) To find g1
Put 1.2V on filament and then have +9V via 10K Ohms with -ve to either filament pin. Which ever pin has the most current is g1.

2) To find g2
Put 1.2V on filament and then have -3V via 1M Ohms with +ve to either filament pin on the pin identified in 1. Have +30V via 100 K to each unknown pin with -Ve to either filament pin. Highest current is probably g2.

3) Strap unknown two pins (one is anode and one is g2). Verify with 33K load and +30V that the current is more than g2 and varies with g2 and/or g1. If this is true, then g2 is correctly found.

4) Anode may be identifiable by inspection, otherwise connect the g1 found to -1V to -5V (adjustable). g2 to +30V via 33K and try one unknown to 0V and the other to +30V via 22K. See which way round works best like a pentode.

[Murphyv310]

Hi Michael.
Many thanks for the help and tips. I'll certainly give all the suggestions a try over the next few days and report back.

[Mike Watterson]

I think the vendor confusion is:
1Ж26А - пентод ВЧ повышенной удаpопpочности. Выпускался недолго, заменен 1Ж36Б.

1Ж26А - high-impact high-frequency pentode. Produced for a short time, replaced by 1Ж36Б.

High Impact usually means for "fuze" application. i.e. high on a firing a shell, not the actual impact.

Does it have a top wire or not? It does look on ebay as if there is no top wire.

[Murphyv310]

Hi Michael.
Here is one of the valves, no anode connection on the top.