1J26A Rod Pentode

[BusyBee]

I too have that Nasa schematic. I also have a copy of the document that it came from, if anyone is interested. It does show four circuits, if I remember rightly.

Yes, please.

But you could run two with filament in series, 16 mA to 18 mA and the  gm is squared.

I did a very low power TRF AM radio once by using very low collector currents, which means low gain, but the gains multiply and the currents add. Ran for over a month with no on/off and a crystal earphone off an AAA cell. Matchbox, small rod aerial and no aerial wire. MW & LW. Penalty is it's noisier.

Me too if that's possible Tracy.

Here is the document, as I have it. It may have come from archive.org. I also attach an extract from a valve data book I have which has the electrometer valve types mentioned. There are more in the range which I have information on but didn't want to make the filesize too big.

Thank you for posting the other information Trevor 


Tracy

  Electrometer_amps.pdf (Size: 548.56 KB / Downloads: 6)
  em7_to_10.pdf (Size: 3.94 MB / Downloads: 4)

PS: I probably have lead diagrams but these are elsewhere in the book.

[Mike Watterson]

Thanks BusyBee aka Tracy, so my memory that it was somehow a NASA document with Russian sources was correct. I wonder what Electrometer circuit NASA are using today on Mars? Yes, at least on Rover has an Electrometer.

I have an old Japanese VVM with 100 M Ohm input impedance. Some DVMs are 1 M, some 10 M and some are 100 M.

The datasheets suggest only the ЭМ-10 could be a rod tube and all may use a top wire for g1 rather than the anode. However the ЭМ-9 may be an interesting dual triode for a mains based, or car battery amp. The ЭМ-8 and ЭМ-9 seem to be 6.3V 100 mA heaters and run on low anode voltages. Though many "mains" valves to work on 12V HT, see car radios. The ECH83 is actually just an ECH81, either can use 12V or 150V HT as they are just labels.

[BusyBee]

It would be interesting to know what they use although we can problably be faiirly certain they don't use valves. Maybe their equipment is encapsulated though so semiconductors inside a valve envelope?

I attach here for completeness the lead diagrams. The others of the эм series which I have data on are the эм4 which is a directly heated triode, эм5 and эм6 double anode / grid indirectly heated tetrodes and the эм11 and эм12 indirectly heated tetrodes. I only have some эм6 which are standard (B9a type) bases and эм7 wire ended subminiature triodes which have their grid lead at the top. I have only utilised them for electrometer type / DC applications.

(Read 'рис' on the data page for the relevant lead diagram number).
  Electrometer_leads.pdf (Size: 2.64 MB / Downloads: 6)

As far as I am aware none are 'rod' type.

Tracy