1p24b-v (1p24b-v) also 1p24b

This valve (tube) while only slightly bigger than the other 1.2V Russian Rod Pentodes (10mm dia rather than 8mm and also only slightly longer) is about 2.5W in Class A or possibly nearly 20W for a pair in class AB push pull. It's designed for RF P.A. output, at least up to 60MHz.

While the 1j29b is roughtly a miniature replacement for DL91 or DL96 in function, but able to work for RF, the 1p24b (or 1p24b-v) is more similar in power to an EL42 or EL85 but designed for RF. The extended data shows Triode connected curves (maybe 3W Class A) as well as Pentode curves.

My own Triode mode measurements

G1 is connected to f+, f- and then -5 below f- (i.e. regard f- as OV)

There is also specified a shorter lifetime 800W rating (no mistake!) for pulse operation and also driving grid to +5V. Did the Russians make a miniature Shortwave (HF ) or low band VHF Radar with it?

These are cheap (under 1.50 € / $2.00) including postage on Ebay in small to big quantities. Perhaps an interesting Audio amp?

For the 2W+ of course it doesn't use the regular 90V battery HT but between 140V to 200V depending on power and lifetime.   The G2 Screen Grid is rated at 1W.

The 1p24b-v purchased have an unusual "ribbed" glass envelope. The ribs are depressions rather than raised.

 

1П24Б-В  (=1p24b-v) Longer life more endurance than standard (This is common on Ebay)

1П24Б-Р  (=1p24b-r) Longer life more endurance than standard

 

Filament

Like the 1j29, the 1p24b has a centre tapped filament for 1.2V or 2.4V operation. Like all the Russian Rod Pentodes the filaments seem optimised for NiCd rather than Zinc Carbon of the European D or USA "1" series. A small series resistor dropping 200mV when using Alkaline Cell seems reasonable.

The typical filament current at 1.3V is 110mA series or 220mA parallel for the 1p24b-v. Not nice compared to an DL96 (25mA series 50mA parallel) or 1j29b (30mA series 60mA parallel) or even DL91 (50mA series 100mA parallel). But a better comparison is with heater power of EL42 or EL85 (1.2W vs 0.145W!)

Fifth element on Russian Tubes (valves) post 1950

The 5th element is optional. It consists of a dash ("-") followed by a single character or a combination of characters, and denotes special characteristics (if any) of the tube:

• V (Russian: В) - increased reliability and mechanical ruggedness (such as low susceptibilty to noise and microphonics).

• R (Russian: Р) - even better than V

• Ye (Russian: Е) - extended service life.

• D (Russian: Д) - exceptionally long service life.

• I (Russian: И) - optimised for "pulsed" (i.e. switching) mode of operation.

 

See the Article on Russian Subminiature Tubes.

 

Attachments:

• 1p24b triode mode (4 KB)
• rod filaments (15 KB)

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1p24b-v 1П24Б-В

Cross-section with diagrammatic view of two "f-" filament feeds at top.

Glass (shown grey) is aproximately 10mm diameter and has 4 dimples.

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