Russian subminature Pentodes & Triodes

[Neil Purling]

I haven't seen any on-line when I have been searching. I have some 1j24b and I wanted another type. Have they all disappeared?

Right now I am having more luck finding 1920's Cossor 2 volt valves than the Soviet military rod pentodes & triodes.

Advice wanted on the most effective search method, I am not asking for any member to sell or otherwise part with their components.

I want to buy my own from wherever I find them, with the help of any advice I receive from you.

[Mike. Watterson]

They are all available on ebay
See my site http://www.radicalvalves.com/russian...od-pentodes-1/
I hope to add more information.
To replace old 2V valves you should use the high power 1p24b

Valve 	Cyrillic  f mA	IaVg1=0 Vg2 	HT	Pa	gm 	IkMax	RL1 	RL2	Notes
1p24b 	1П24Б 	198 	18 	120 	150 	2500 	2.5 	25 	5 	22 	CT filament @ 98mA Series. 1W G2 and 800W peak

Use the filaments in series with a 10nF ceramic and 20uF to 33uF capacitor at centre tap to filament - supply on the adaptor.
Put a coffee tin cut up sleeve to screen it, connected to f- / LT-
Ukrainian, Bulgarian, Russian sellers on ebay.
try 1p24b and also 1p24b-v
see pentodbg in Bulgaria.
If selecting "international" doesn't result in "hits" on ebay search, then try ebay.ie and then ebay.com rather than ebay.co.uk
Ebay international search gives different results on different domains.

Buy 10 off

There are NO rod Triodes!

To use as a Triode
g3 must connect to f- or f+
g2 connects to Anode.

The 1p24b data has triode curves.

To replace old 2V types the filament should be run off 2V lead Acid, or if using 2x NiMH in series, then add series resistor or 1N4007 per adaptor to under run the filament. Two NiMH are nominal 2.6 (to 3V fully charged on a trickle charger). 2V valves are meant to run 1.8V to 2.2V (and never while lead acid Battery is on charge). The Rod Pentodes work fine at 0.9V or 1.8V.

Under running the filament reduces bias needed and reduces gain to late 1920s early 1930s value.

For later 2V types I use the 1j29b. I have successfully replaced dual octal 2V Pentode with a pair of 1j29b running from 2V. A series resistor and capacitor was added in the adaptor to reduce Vg2 which made it work properly off the existing Vg1 bias. Otherwise a much more negative bias is required.

For non-output 1929 -1931 model 2V types the 1j29b triodesed with series filament may be a better choice than 1p24b, so buy 10 of them too.

I can furnish all the datasheets.

[Neil Purling]

I was wanting the Russian valves for a Homebrew, not to replace absent 4 pin battery valves in something.
Is the 1j24b the best choice as a regenerative detector?
I have a circuit which seems to use entirely 1j18b type, detector and three in the AF stage off 18V of HT.
You could not use the 1J18 to try my favourite Hartley type of circuit as g3 is internally connected to cathode/filament.
What circuit may be reccomended as simplest? I have never used these valves before.

[Mike. Watterson]

The 1j18b is early type. Not recommended.
The 1j24b is third generation. It's only limitation is really power.

Use them as you would a DF92. They are sharp cutoff.

They are NOT 1.4V like DF series, but 1.2V NOMINAL.

You can use them in any Pentode direct filament. For common grid you simply put a ferrite, dust iron or laminated transformer (depending on frequency) wired as common mode choke to f- and f+ from LT- and LT+ connected so DC passes and it's thus AC choke. The start -finish so the f- and f+ currents cancel in transformer (note the g2 and Anode currents don't cancel!).
Put two capacitors in series between f- and f+ and then centre point is RF (or AF) input. This is standard for direct filament common grid mode. In common grid mode the g3 must connect to LT- (or LT+ sometimes). For triode mode, connect g2 to anode. But g3 must still connect to f- or f+ or LT- or LT+, unlike triodising a DF97 (behaves like a DC90).

g2 controls gain and effect of g1 bias. At g2 = 25V the gain is low and bias can be nearly 0V on g1. At g2 = 55V gain is about maximum and g1 bias needs to be more negative. g2 can thus be L.O. input direct from anode of an Oscillator to use valve as a Pentode Mixer.

g3 can also be used to control gain or as mixer input at certain g1 & g2 conditions.

These are not really Pentodes but dual electron beams with electrostatic lenses. But they have a Pentode characteristic.
Simply using a resistor and a capacitor to set g2 volts as on a real Pentode can have unexpected results (it's possible) as below the pentode "knee" the Anode and G2 behave like a current mirror. Above the Pentode knee the g2 current is miniscule.

They have no screening. So I cut up Lidl coffee tin to make earthed screens.

The 1j29b with one 1/2 filament is about equivalent to DL96, but with DF97 frequency response! With both parts of filament you get x2 gain and x2 power. More power than DL94 and still DF97 RF performance.

2 x 1j24b in push pull class B needs about -6V or more negative bias and gives 500mW, but only using about 22mA filament current total.

2 x 1j29b with only half filament in push pull class B needs about -6V to -10 or more negative bias (depending on G2) and gives more than 1W, but only using about 54mA filament current total. Use both halves of filament (108mA@ 1.25V) and it's a little over 2W. Audio, or 50MHz depending on design! If careful you may be able to have over 1.5W and 3W. In theory if you are happy with less than 1000 life you can even have sustained 2W and 4W.

The 1p24b is mad. A pair in class B RF push pull can be close to 20W. Paralleled and triodised you can mimic early PX4 /PX25 etc to restore robbed Models.

[Mike. Watterson]

P.S. a bit mad to use ANY battery valves other than military stock esp, pre 1940 types for home brew. There are mains valves still made and some types plenty of stock. The 2V types are rare and needed for restores.

[Mike. Watterson]

The 1j37b is higher filament current. It's 2nd generation type. It allows AGC & mixer action as it's dual grid. Differential signals are not amplified much and common mode to both grids are amplified a lot. It's really quite strange. You can tie g2, g3 and anode to ground and use the two grids in Gammatron mode. One is input and the other output.

[Neil Purling]

How about some pointers to simple but effective circuits?
It's been snowing & I don't feel like venturing very far.
Stuff I can make from raiding my boxes of bits.
I have the mortal remains of a Pye P123BQ. Wanting to scavenge it for the variable capacitor. Was it's value any less than 500pf?

[Mike. Watterson]

Check the links
http://www.radicalvalves.com/russian...od-pentodes-1/
Also search on the Radiomuseum
Copy a Vidor Vanguard AM parts as it uses triodised Pentode as Local Oscillator and Pentode as Mixer on AM.

You only need up to 270pF if you have suitable coils and minimal stray capacitance. A capacitor out of a £5 pocket radio is fine.

See
http://www.radiomuseum.org/forum/hom...adio_help.html

[jim_jobe]

There's a nice regenerative RX design in the current issue of Sprat the G-QRP club journal, which uses two 1J18b and a 1J29b, plus lots of other interesting designs. At only £6 per year membership I can highly recommend it.
I've tried putting 1J18b valve into ebays search box but got nothing - you need to enter 1j18b tube!
Jim
M0JBJ

[David G4EBT]

Neat little three-valver design here with a nicely drawn circuit, covering 720kHz - 8 MHz, with coil winding details etc:

http://www.m0dgq.co.uk/images/rod.pdf

Tempting!

[David G4EBT]

Originally Posted by jim_jobe

I've tried putting 1J18b valve into ebays search box but got nothing - you need to enter 1j18b tube!

Yes, if you enter '1j18b' you'll find them, presently £5.35 for ten + £7.32 P&P from Ukraine.

I think the actually numbering and lettering of the tubes is in 'Cyrillic' so maybe the translation into Arabic letters & numerals causes a bit of a hiccup?

Dinky little things - there must be millions sloshing around I guess.

[Mike. Watterson]

But the 1j24b and 1j29b are both superior.

There are millions. The 1j17b and 1j18b are best avoided as lower performance. The internally tied g3 to filament limits 1j18b use apart from it and 1j17b being earlier types.
The 1j18b was last made about 1977. The 1j24b and 1j29b up to 1990.

Substitute 1j24b for 1j18b. Check bias and anode current. tie g3 to f- and put a screen sleeve on each tube wired to f-.

If you use Alkaline AA cells or PP3 for HT+, then ditch the pots and tap the g2 on V1 and V2 to about 45V and V3 to 54V. I'd go for 67V HT for more volume /gain. A 45V HT is possible, then all g2 connections just go to HT+

[Neil Purling]

Has anyone done a signal tracer with these that gives a decent audio o/p?

[Mike. Watterson]

That seems pointless. 45V 5mA HT and 33mA LT for 3 x 1J24b vs about 2mA @ 3V for a transistor tracer.

You could use just an 1N60 and 1 x 1j24b and 67V HT, a large 32 Ohm earpiece or small 16 Ohm speaker and about 4mA HT, 11mA LT from an NiMH AA cell. I've built that and it works.

http://www.radicalvalves.com/herge-radio-1/
Originally 1j18b, but replaced with 1j24b

See also
http://www.radicalvalves.com/tatiana/


(P.S. that's my site, I must add more updates!)