1j42b Valves

[pwdrive]

Cheers Trev.

Lawrence.

[Mike Watterson]

Here is maybe the Sputnik's (wanderer) transmitter

   

[Pat Pending]

Hello gents, interest whet by this topic I've just found my "stock" of rod pentodes and they are 1j29b's, are they useful at low anode voltage's like the 1j24b's? I've tinkered a couple of nice syncrodyne/re-gen hybrid radios using a Franklin oscillator topology with a JAN6418 as an input device and an 18volt ht, these are very good, but are photo sensitive (not a problem) and very microphonic (problem!) Would the rod pentodes be an improvement I'm wondering?

Cheers, Andy.

[Mike Watterson]

No, the 1j29b are power devices, up to 150V anode volts. They will just about work at 30V. The 1j24b ( Less than £1 each in quantity!) or even 1j18b are far better at low voltage (18V is possible, though 24V is much better). They will be usable to replace B7G audio out in a 45V battery set, but far better in 67V and 90V sets.
More powerful than DL94 audio out, yet better at RF than DF97 or DC90

You only need 1/2 the filament on a 1j29b to replace a DL91 / DL92 / DL96 in a 1.4V set!

I mount the metal screen on a foam pad. I've not tested them for microphonics as such, but they are designed to survive vibration (not same thing).

Here is a subminiature very low power magic eye to suit.
http://golbornevintageradio.co.uk/forum/...p?tid=5891&pid=61978#pid61978

Note that ECH81 (=ECH83), EBF89, ECC82 and many more work off 12V to 14V HT and were used in car radios where heater current didn't matter. Used with transistor audio out. Earlier car radios used transistor inverter for 120V HT and before that they used vibrator to get 120V HT, so valve audio out was used.

[Pat Pending]

Thanks Mike.
If I try another set like those I mentioned, I'll get a few  more of the 1j24b's and give those a try (dunno where the others I had went, recommend a reliable supplier?), the car radio types I have tried, but for portability it means a heavy SLA battery,

Cheers, Andy.

[Mike Watterson]

I've had no problem with any of the Ukrainian, Russian, Bulgarian suppliers of ex USSR gear on eBay. Your own mileage may vary.

All the types are really different filament currents, like old Telefunken Y8 series metal can battery vales/tubes. Not designed for overall series mode like D9x series.
All are designed for 0.8V to 1.3V rechargeable cell operation (nominal 1.2V) rather than the 1V to 1.6V of the normal dry battery valves (nominal 1.4V).
Very long life if filament voltage is carefully set. Useful operation down to 0.7V

They had several applications:
Proximity fuses in bombs, shells, missiles.
MiG fighter radar and two way radio
Early satellite and spacecraft beacons and two way radio
Military man pack and vehicle radios
At least one commercial two way radio for forestry workers.

No Domestic stuff known.


1j17b: Older version of 1j18b, not worth buying unless stupidly cheap.
1j18b: medium filament current, lower performance, older type. Good for old 1920s to early 1930s circuits. Cheapest.
1j24b: Very low filament current, about 12mA, can replace DF97, DC90, DF96, DF91 etc, but really no AGC, sharp cut-off like 1U4 or DF92. About 24V to 70V HT. Screen grid Vg2 is best gain at 55V and very low gain at 20V, so Vg2 can be used for amplified AGC in or DC gain control, like 1U4.
1j29b: higher current, series or parallel for the two filaments or even just use one for 1/2 power and 1/2 gain. Better performance as RF preamp or RF or AF power out. RF power, but can replace DL94 but at close to DL96 consumption. Can be up to 150V HT, OK at 45V.
1p24b: Very high filament current. Can be used linear, but designed for up to 800W peak! Probably three in parallel can simulate an earlier PX type triode.  Really unless you are building high power class B push pull RF transmitter. HT 45V to 200V

1j37b: Simplified version of 1j18b (less shielding rods), but both g1 plates brought out rather than internally connected. Mixers, AGC, DC volume control, frequency doublers and active AM detectors etc. Simulated remote cut off. Quite high filament consumption. 12V to 90V HT. Can be used as a gammatron.

1j42a: Last ever design. Optimised for 6V HT. Works 4V to 12V, similar but not identical filament current to the 1j24b, about 12mA. Completely different design to suit the low HT. The g1 plates brought out separately like 1j37b to facilitate Mixers, AGC, DC volume control, frequency doublers and active AM detectors etc. Simulated remote cut off. Can be used as a gammatron.

1e4a: Magic Eye at about 12mA filament current. Not a rod tube and very small. Intended for use in Military sets using the Rod Tubes.

IV15, iv15: Really unrelated to Rod Tube radios. Similar idea to the DM160 VFD, http://www.radiomuseum.org/tubes/tube_dm160.html designed to be a long life lamp replacement but with on/off electrode for transistor voltages, unlike a neon. Two in series will run off one NiMH cell as they are 0.6V filament. Medium current. They will work as a low gain triode amp. Pretty.


There are also some neon based bargraphs!

[Pat Pending]

Thanks Mike, I may speculate on some to try out. Thanks for the summary also, it will help when picking the bones out of the published data for an application.

Cheers,
Andy.

[Murphyv310]

   
Hi.
This is what I use for my experiments, simple breadboarding!!
Saves damaging the valve and makes changes easy.

[Pat Pending]

Clever! Is that a strip of copper laminate Trevor?

[Mike Watterson]

I use a regular IC breadboard
   

Then sometimes veroboard
   

But small terminal blocks with leaf contacts below the screws work.

I also use a plastic sheet with holes poked and point to to point wiring.
Push-Pull Class B using 2 x 1j24b and an iv15 indicator as phase inverter.
   
The second iv15 is just an indicator, they serve as scale lamps, filaments in series off the 1.3V NiMH
The transformer is a 110-0, 110-0 to 6V or 9V 3W type.



Two Vero style tag strips stuck to coffee tin, which is also earth, wide enough apart for anode end to the base. Then the next tube mounted in the opposite direction.

I did also cutout vero mounted in small Eddystone box, to gain space: