Portable Radio using Vacuum tubes / Radio Valves

Create a radio receiver using vacuum tubes (aka radio valves). It will be portable, using available parts, and will look cool :)

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The aim is to create a radio receiver using technology from the dawn of electronics (approximately 1920 onwards when amplifying vacuum tubes were invented).

My project will use "old style" electronics but will try to use parts that are available. The radio receiver should be portable and it should actually work (meaning it can receive radio stations). Most importantly it should look good, featuring polished wood, shiny brass and glowing radio valves!

Key features of this project

  1. Use "old style" electronics. These can be original electronic components (sometimes known as "NOS" or New Old Stock), or could be modern reproductions of old components. It can also include hand-made components that date from the time. A radio experimenter from the 1920's could wind a coil (inductor) so we can do the same.
  2. It should look artistic in a technical kind of way. Polished wood, shiny valves, brass terminals, and unusual looking components should all feature. The wiring should not look complicated and there should be no "rats nests" of wires.
  3. Parts should be available. I can't promise parts will be cheap or easy to find - but it should be possible to make, adapt or buy all the parts from somewhere.
  4. It should not need advanced skills to build, nor should it need metal working skills. It should be buildable using hand tools, a basic knowledge of electronics and a multi-meter.
  5. The radio receiver should be portable. It will be in a self contained case with batteries, a loudspeaker and a handle.
  6. It should work on long waves, medium waves and possibly short waves.
  7. To make this work, the radio will have a tuned circuit with a regenerative detector (triode or pentode), followed by an audio amplifier that drives headphones or a loudspeaker. Low voltage batteries are needed for the vacuum tube (valve) filaments, and higher voltages for the detector and the amplifier. The radio is built on a wooden "breadboard" to make construction easier and to avoid metalwork (although it may need a metal front panel). These techniques are known to experimenters from the 1920's.
  8. The design process will be iterative, this means I make it up as I go along . But there should eventually be a "useful working version" that can receive radio stations. Anyone following along should be able to reproduce it themselves, and will hopefully understand the design decisions that were made.

Background Information

  1. "RCA Receiving Tube Manual RC-19", (c) 1959 Radio Corporation of America. My copy is a reprint, but any original or reprint from about 1950 to 1970 should do. It provides the pinouts and details of the tubes / valves in use.
  2. "Secrets of Homebuilt Regenerative Receivers", C. F. Rockey, (c) Lindsay Publications Inc 1996. This has good information on construction techniques and some sample circuits from publications of the 1930s.
  3. Use to look up details of individual tubes / valves

Tools and Equipment

I'm new to hackaday and just spotted a "components" section which I will use. It's important to write up the other tools and equipment needed, so here we go:

  1. Basic wood working tools such as a handsaw, set square, ruler, and a sanding block and sandpaper. Use these to make a "breadboard" and wooden runners that go underneath.
  2. [Optional] Wood varnish and a paintbrush, to cover up scratches on the breadboard and to make it look nice.
  3. A hand drill and drill bits. Use these for "starter" holes for wood screws. Also if you have an aluminium front panel you need the drill to make the holes for the components on the panel.
  4. Soldering iron and solder
  5. A multi-meter, any kind will do.

Circuit Diagram

Since this is an electronics project I should publish a circuit diagram soon!

  • 1 × 1F4 pentode Type 1F4 pentode with 5 pin base and 2 volt filament
  • 1 × 1A4P pentode Type 1A4P vari-mu (variable gain) pentode, with 4 pin base and top cap, and 2 volt filament
  • 1 × 1H4 triode Type 1H4 triode with octal base and 2 volt heater. This is a later and cheaper version of the type 30 triode
  • 1 × 19 double triode Type 19 double triode with 6 pin base and 2 volt heater
  • 2 × No.6 battery 1.5 volt This is a large 1.5 volt battery (2.5" diameter and 6" high). These are difficult to obtain so a D cell can be used instead.

View all 6 components

  • 29 May 2023 - Tube Sockets

    Will05/29/2023 at 16:06 0 comments

    Tube sockets (also known as valve sockets) come in two main forms: chassis mounting which is where you make a circular hole in a metal chassis and fasten the socket to it, or breadboard mounting where you fasten the tube socket to a wooden breadboard. The majority of tube sockets are chassis mounting because the metal chassis helps screening between circuits. But the breadboard mounted sockets are easier to work with because you don't have to make a large circular hole. Here they are: 

    You can see the 4 pin sockets at the back of the photo, and the 5 and 6 pin sockets at the front. These were difficult to find, and if you're building this project it's perfectly fine to use chassis mounting sockets and spacers, to hold the socket above the breadboard. But I think the breadboard sockets look better.

    The 4-pin sockets are called UX-4, the 5-pin UY-5 and I think the 6-pin is UZ-6. Actually I'm not sure about the last two, you could probably call them UX-4, UX-5 and UX-6.

    In early radio construction you didn't need a soldering iron because the sockets used thumb screws and the circuit could be built by wrapping solid core wire around the thumb screws and nuts and bolts. But I couldn't find any using thumb screws so I will have to use the soldering iron.

  • 17 May 2023 - Beauty Parade!

    Will05/17/2023 at 21:29 0 comments

    I bought most of these a while ago but here they are:

    Presenting from left to right:

    • 1A4P - a pentode with a 4-pin base, the top cap is the control grid.
    • 30 - you can just see the "30" on the glass, this is a low power triode with a 4-pin base.
    • 1F4 - a "power" pentode with a 5-pin base, able to put out 0.5 watt of audio at maximum ratings :)
    • 19 - a double triode with a 6-pin base. This can be used as a class B audio amplifier to deliver a mighty 2 watts of audio!

    Some interesting facts I learned:

    • The earliest vacuum tubes had a two-digit numbering system (30, 19 etc etc).
    • In the 1930's was a "newer" system number letter(s) number where the first number is the heater voltage (approximately), the letters are arbitrary and the last number is the number of electrodes. The 1F4 uses a last number of 4 because it has the filament, control grid, screen grid and anode, and the suppressor grid is internally joined to the filament.
    • All these have 2 volt filaments designed to run from batteries, either a lead-acid cell or a higher voltage fed through a fixed or a variable resistor. When a variable resistor is used, it was called a rheostat and it was adjusted to allow for declining battery voltage during use.
    • The filament is very thin and it runs red-hot (or nearly red-hot) and emits electrons, usually just a few milli-amps. A common mistake when using these valves is applying too much voltage to the filament, which burns them out and makes the valves useless.
    • Any of these could be used as the regenerative detector, or as a low power audio amplifier to drive a pair of headphones.
    • The "power" pentode and the double triode were designed to drive loudspeakers using audio transformers. 
    • Some simple radios used the 19 double triode as a regenerative detector AND an audio amplifier. Thus making an entire radio from one vacuum tube.

    And some terminology:

    • These battery valves are directly heated, meaning current is passed through a fine coated wire causing it to heat up and to emit electrons. This heated wire is the cathode and is also called a filament (USA) or a heater (UK/AUS).
    • Vacuum tubes (USA) or radio valves (UK/AUS) are different names for the same thing. Sometimes I use one and sometimes the other.
    • Valves have an anode which is positive, similar to the collector of an NPN transistor. The anode (UK/AUS) is also called the plate (USA) and collects the electrons emitted by the cathode. 

  • 15 May 2023 - Low Voltage Batteries

    Will05/15/2023 at 21:17 0 comments

    Every project starts with a single step and I have been thinking about this project for a while. The vacuum tubes / radio valves in this project have 2 volt filaments, although alternate tubes/valves can be used that have 1.5 volt filaments. The 2 volt valves were "early" valves designed for lead-acid accumulators and the 1.5 volt were "later" valves invented around the 1940s for dry batteries. So I decided to order two "old-style" 1.5 volt batteries to cover both scenarios - if I use the 2 volt valves I will put the batteries in series and use a resistor to drop the voltage to 2 volts.

    I think these are called No.6 batteries because they are 6 inches tall:

    You can read more about them here:

    They are also used in electric clocks and I bought these from

    It's perfectly OK to use 1.5 volt D cells and buying these No.6 batteries was a bit extravagant. But they look suitably retro! 

View all 3 project logs

Enjoy this project?



Will wrote 05/29/2023 at 16:12 point

Thanks for the feedback! I am doing my best to avoid "scope creep"

  Are you sure? yes | no

74hct04 wrote 05/24/2023 at 19:46 point

Interesting reading!

Looking forward to seeing this project progress :-)

  Are you sure? yes | no

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