One valve radio

This is a one valve [tube] radio that believe it or not I constructed 48 years ago. It remained lost but was discovered again during a recent house move. The valve used is a battery R.F. pentode dating from around 1948 on a B7G base. The type number is DF91 or the American equivalent, the 1T4. This valve was used extensively in radio equipment during the second world war and was widely available for a few pence on the government surplus market. The receiver is a simple detector with reaction [feedback]. In simple terms reaction brings the valve into a high state of efficiency improving selectivity [being able to seperate stations] and sensitivity [able to pick up very weak signals]. This simple circuit dates from the 1920's and can be used with any type of radio valve with slight modification. The filament supply [1.5v] is supplied from a single cell and the H.T. supply for the anode from three 9v batteries in series. Surprisingly the circuit will operate with an anode [plate] voltage as low as 18v and weak signals can be heard as low as 9v! The volume in the high impedance telephones is very good but I have connected to an old valve amplifier to demonstrate its capabilities. Thanks for watching.

Category:

Science & Technology

Tags:

• One
• valve
• radio.
• Old
• Valve
• Tube

[tubesclan]

hello I would be interested to rebuild the beautiful circuit shown in this video. Would it be possible to have the scheme? thanks hello Claudio

[vinylseat]

@tubesclan Hello Claudio, I'm not sure what you mean by 'Scheme'. The circuit is printed and explained on another posting on my pages. Please let me know if you have any specific questions about it. J.

[ccronn]

I am really loving that amplifier you are using! Is it a mono amp?

[vinylseat]

@ccronn Hello! The amplifier was a kit I built in the 1960's ECC83 preamp/ driver, EL84 output, EZ80 rectifier. Nothing special but like all valve amplifiers, sounds great. The output is 5 watts RMS so adequate to fill a large room. The valve line up is conventional but much older amplifiers using valves such as the 6SN7, 6V6G and 5Z4 will give identical performance. Circuits and valves from the 1930's will give similar results. A lot of hype exists around valves and amplifiers. Mostly rubbish!

[dh1ao]

beautiful. love it. Really nice audio from such valves

[LZ2SM]

Where can I find the circuit diagram?

[sweetgyy]

very nice . i miss those old radios

[tubesclan]

@vinylseat

Ciao J.

thank you very much

I have now seen the wiring diagram of your beautiful radio

thanks again and congratulations

Claudio

[vamtim]

Nice video, great little radio and gorgeous amp!!

[protelboy]

Very nice project, good thing you found it after all these years! I love old tube technology, it is so much more interesting than solid state and sounds much better too. I built a 300b stereo amp a couple of years back and the sound is brilliant, much better tan any transistor amp I have ever heard.