herge-radio-1

 Russian Rod Pentode, Uncategorized  Comments Off on herge-radio-1
Apr 042018
 

 We’ll call this 1 valve Regenerative Radio “The Hergé” in honour of his research and attention to detail. (fun stories too)

Hergé wrote that strip (in French) for the Belgian newspaper in 1934 or 1935 just after the Japanese invaded China and blew up the Manchurian Railway.
Tintin is picking up Japanese transmissions to/from spies in China in Morse.
Note DF loop aerial.

The Japanese lodged a protest with the Belgian Embassy after it was published!

It was later coloured and published in English as “The Blue Lotus”. You can buy the full story in most bookshops and online.

The Hergé will be a one valve regenerative Radio running off batteries (3x PP3 = 22.5 / 27V, 6x PP3 = 45V/54V or 8 x PP3 = 60V/72V ). Optionally a second 1j18b can be added as an audio amplifier, especially valuable if you want to use 27V. You can even use 2 x PP3 (16V to 18V) if you add and amplifier. The valves (or Tubes) used are Russian Sub-Miniature Rod Pentodes made entirely for Military use.

Also you can add a 3 x 1j18b Headphone amplifier for ordinary 32 Ohm “player” ‘phones (18V to 45V, 3 x AA cell LT)  or an amplifier with 2 x 1j18b and 1j29b for a loudspeaker (45V to 90V).

You can wire it for LW, MW or SW, or fit a switch for two bands or more.

Unusually much of the wiring will use plastic screw terminal blocks.

Testing the design concept

Valve on IC breadboard!

Basic Radio Concept

The actual  radio “front” is regenerative Tuned Radio Frequency (TRF), The regenerative feedback (using coil labelled Yellow & Blue) cancels out losses in the tuning circuit thus making the tuning sharper and signal stronger. Too much feedback and the circuit is a small MW transmitter! 

Basic concept schematic

Early version of radio. Current version is a little different.

Basic concept. It’s using a valve made in 1980s that was designed in mid 1950s.

Specification

Approximately 170KHz to 270KHz on LW and 550KHz to 1200MHz on MW.

4 x AA Alkaline nominal 6V LT @ 21.5mA  (about 120 hours),

4 x PP3 Alkaline nominal 36V HT @ 700uA  (about 250 hours)

4 x 1j18b valves. (Cost under 3 Euro total excluding postage)

No external aerial or earth required.

Warning!

Note that higher voltages are dangerous, especially above 50V. There is also risk of fire and burns or even explosions if NiMH are used to make higher voltage packs.

Comparison

The latter half 1950s Battery portable radio sets used a loop aerial in the lid. They used 125mA LT 1.5V and about 6.5mA HT from 90V pack. Line up filament Heptode frequency changer / oscillator / mixer. From 1954.”>filament Heptode frequency changer / oscillator / mixer. From 1954.”>DK96, filament direct oxide cathode. Replaced earlier 1T4 / DF91″>filament direct oxide cathode. Replaced earlier 1T4 / DF91″>DF96, DAF96 and DL96. Usually LW & MW.  The earlier 1950s and late 1940s miniature valve sets used filament direct oxide cathode. Equivalent with RCA 1T4. Replaced by 25mA DF96 “>filament direct oxide cathode. Equivalent with RCA 1T4. Replaced by 25mA DF96 “>DF91 which is twice the filament current. They had more variation of valves and design and up to 250mA LT 1.5V current.

The “Hergé” uses 24mA from 4 x AA cells (6V) and about 1mA from  4 x PP3 (36V)

Experimenting with 1j18b

 Experiments, Russian Rod Pentode, Uncategorized  Comments Off on Experimenting with 1j18b
Apr 292014
 

Experimenting with Russian Rod Pentodes

Here is Russian 1j18b (aka 1zh18b, 1sh18b really 1Ж18Б ) on IC breadboard. The 1j24b and 1j29b are actually better purchases.

Testing 5.4MHz Hartley Oscillator at 16V and 25V.

Dscf2010

1j18b with 1.2V NiMH for filament and  +15V to +32V test bench PSU

This valve concept  was invented in 1950s but many models only entered production in early 1960s and used up to 1980s in MIG fighters and portable Military radio. Superior frequency response to many Germanium transistors (120MHz vs 3MHz), more stable, high impedance lack of Silicon Transistor production is many the reason for long term use. No recorded Domestic/Consumer application.

Heater filament power is from 12mW to 50mW depending on model compared with 2000mW for typical US/European domestic valves (tubes). Recommended HT typically 45V (max 60V) to 150V for 4W “transmitter” versions. But operation at 16V upwards is definitely feasible. Apart from the 4W models, the valves are so low power that in some application circuit the power consumption is similar to transistors and the valves can be mounted direct on PCB or stripboard (veroboard). The 1j37 is unusual as although it has single anode it has dual control grids at the same place. Read the Radio Museum article to see how this is possible. Regular valves with a single anode and cathode can’t be made like that. It is like a dual gate depletion mode cascode MOSFET. (A pentode with suitable voltages on the 3 grids behaves like cascode circuit. I think the 1j37b is a pentode with a 2nd identical control grid, not a hexode)

Original circuit from German Website (scroll down)

hartley_orig_dl1adr

For operation at 16V to 32V move R1 grid bias from ground (f-) to +1.2V (f+), makes grid closer to 0V of cathode.

Do not exceed filament)”>filament)”>1.2V filament. These are not 1.5V filaments. For NiMH battery which is a bit more voltage than a NiCd, a 10 Ohm series resistor gave about 1.17 to 1.2V on filament.

See Radio Museum Article

Dscf2009

5.4MHz, 3V RMS on 25V HT (about 1V RMS on 16V HT)

Grounding the Anode and using G2 as anode with 42V HT operation as a Colpits oscillator up to 100MHz is possible. So using it as a triode is possible,