Hi.
I've ordered ten of the above from a seller in the Russian federation. These are capable of delivering more power than many of the other Rod Pentodes, the spec is available on the Radio museum site.
I've got a couple of projects in mind.
They are supposed to be here mid June but I'd imagine that could be longer due to Covid-19. Watch this thread over the next few weeks.
As a consequence the filament power is about 10x the 1j24!
I have some, but the 1j29b do more power than a DL94. I did make a single ended amp and a push pull amp.
You can triodise them and use two to replace the earlier PX4s, or the later ones if running life not important. Also work to VHF in class C or push pull. An earlier version was used in the Sputnik in class B/C push pull.
Also were used for pulse radar 800W on shells and bomb proximity fuzes. Life of minutes.
Hi Michael.
Yes I read about the use of proximity fuses, some how I don't think I'll be pushing them that much. I've learned a lot with other rod Pentodes and want to experiment with these ones. Looking forward to getting them.
Is there some Ra-a data for push pull I’ve got a few transformers hanging around and probably got some 1j29b 1J24b and 1p24b here somewhere.
I can post you a couple if they don't materialise!
A friend has a couple of very old radios, probably used bright emitters or very early coated triodes. No tubes. One is a 1926 superhet. So one idea is to run the series filaments off 2V lead acid (which lowers gain) and fit the 1p24b in a holder made from car headlamp bases (pull out the 3 blades, fit 4 pins) and a glass globe from small pear shaped bulbs that are large enough for the rod tube. I sprayed the inside of one to simulate "black" and one to simulate "silver" getter deposit.
Triodise them. I've verified at at 1.8V (a near flat 2V Lead Acid) the performance is if anything a little better than the original triodes.
I've got some too, aiming for AF P-P amplifier!
I built up the voltage amplifier and phase inverter as a separate matrix-board module, also using Russian rod pentodes, but not moved on to the power stage yet.
Specs for the 1p24b do look impressive...
I will keep my eyes open here as I have yet to investigate their use, other than looking at the data sheets.
For reference, although things may oviously vary, I put in an order for some parts from a location mid Russia which was confirmed on 18th April. It arrived this morning. I received a similar order, placed the same day, from a supplier in the Ukraine yesterday. I was thinking there was a bottleneck but it may have relaxed a bit now.
Tracy
Hi.
They turned up today. They are slightly larger than other rod Pentodes, they have a larger diameter with four grooves in the glass envelope to no doubt stop deformation of the glass in severe heat and improve strength.
I've made a small test rig up to see what RF power can be obtained from these valves. I picked a random crystal and made up an oscillator using a 1j29. Then followed by a PA stage again using another 1j29 into a pi tank circuit to my RF power meter and dummy load. at 40v HT RF output just lifted the meter and using a 6.3v dial bulb lit it just above half brightness. Raising the HT to 100v made the bulb glow very brightly. Although hard to decipher on the meter I was getting around a watt. Parallelization of two valves doubles output to approximately 2 Watts. I now have tried one 1p24b, running with 150v at the anode it gives approximately 5 watts, it runs hot around 80c so I have no idea of life.
The circuit could be adapted for amateur radio QRP applications, assuming amateurs still construct projects.
Incidentally I added modulation and have to say quality is very good. I don't want to upload a circuit as this project could be used for non licensed use, it though was only made for the feasibility of these devices for RF low power circuitry.
Power supply is from 12v via two DC to DC converters for HT & LT. So if modified for amateur use it could be easily used as a portable or mobile TX.
The construction on copper clad board is idea for RF and wideband prototypes.