Prayudi's 12AF6 / LM386 Radio built in Indonesia.

My idea is a tube radio that I can play as an ordinary radio, so I made this 12AF6 AM tube radio with mini amplifier to drive audio. I am using a LM 386 circuit as audio amplifier and a power supply rather than battery as the power.

I started with make a pinewood box. I choose pinewood because the wood texture looks good and easy to work with.

I bought a sanded pinewood board and started my project on 17 May and finished on 22 May. But because my friend and I aren't craftsmen, the box we have made was not very good. It looks unsymmetrical. I didn't varnish it yet because I like the plain color of pinewood. I use FOX glue (a special glue for wood work) to make the box, except the front part I used screws so I can open it and install the parts.

First, I drilled some holes in the front cover part to mount the variable capacitor and speakers. The holes in the top for the tube socket, volume control, regeneration control, antenna ground plug-in, and coil part.

Wheuuh, it's a long weekend for us! But we finished it!

Then I mounted the power supply transformer and adapter circuit in the base. The socket, potentiometer, 12AF6 tube, and audio amplifier came later after I glued the box. To get the antique nuance I use a five-strip terminal to mount all electronics part of receiver, but I used a PCB to make a LM 386 mini amplifier. At first I made a push pull amplifier with a pair of 2SB 178 and 2SA 175 but it didn't work (2 times),so I decided to use an IC. As you can see in the picture the side part is messed up! I placed the tube outside the box as I was inspired by the jargon: a real radio glows in the dark! It's risky to have the parts on the outside because they could get broken. I placed everything on the outside the box to show everyone that this is an unusual radio!

The stereo plug-in in the top right is used as aerial and ground connection, the red for aerial and black for earth. The left knob is use as volume control and the other is for regeneration. My coil form was made from a paper towel cardboard tube. The coil looks dirty because I use cyanoacrylic glue to make wires stick tightly.

At first I built this set on a used disc box and battery powered. The reception is very good and clear. With just a 5 meter high antenna wire I can hear 22 AM stations in my local area and get 2-3 more overseas stations (mostly from Vietnam, Thailand, Kampuchea) when evening comes. But after I placed in the box and used the power supply, the sound is now distorted by hum noise. I guess it came from filter capacitor in the adapter part. I should increase capacity, mine used 1000 µf and a 350mA adapter transformer for 12 volts output. The hum noise is ruins the reception quality too, I lose stations, especially the overseas stations. I don't know why. But it doesn't bother me because cause I've hypnotized and mesmerized by the glow of the tube! So I named this project as: REAL RADIO GLOWS IN THE DARK!

2 Tube ARRL 1930
Regen built by Chris, KD4PDJ

This receiver was featured in the January 1930 QST, just a short while after the type 24 tube was introduced. It uses a 24 for the detector and type 27 triode for the audio amplifier. Both tubes have 2 volt filaments- the 24 uses 45 volts on the plate and the 27 uses 135 volts on the plate.
I am using 5 pin plug in coils made from forms I got from Antique Electronics Supply. With other sets I have built I have had good luck using bases obtained from blown 807 tubes (I used to work as a radio engineer and many of our old AM transmitters used 807's as drivers).
The coil is wound from litz wire, and the front panel is black lexan bought as scrap from a plastics/glass shop.
This set uses both a potentiometer and a capacitor for controlling the regeneration. It takes some getting used to, but most of the regen action is taken care of by the capacitor.

David Williams in England

Here is my first crystal set. It is based on the cigar box set but i could not get hold of one so I used a plain jewelery box from Hobbycraft, a local shop.
   I have also fitted 4 feet which started life as miniature drawer knobs. The whole thing has had 3 coats of walnut stain and then 3 coats of matt varnish.
Editor's note: Those are very nice homemade thumb nuts. Homemade parts always increase the appeal of a set.

William Nielsen's Utah Built Crystal Sets

I got interested in radio when my son asked me to build a one tube radio for a school project. I have an old electricity text that had a set that called for a # 30 tube.I knew nothing of how to even find a tube let alone the rest of the parts. Well, after lots of research and 5 years later, I have collected some parts so I decided to build something other than the ones I collected on Ebay.

The circuit for the crystal radio is from the Radio receiver projects book by Homer L. Davidson. The face and bottom are made of 1/2 inch plexyglass. The dial is an original Atwater Kent dial I found in a friends junk pile, With the variable cap still attached. The crystal set is project #4 The permeability-tuned set in the project book. The coil has 2 windings L1= 25 turns #24 enameled and L2= 97 turns same wire.

The crystal detector is completely hand made from the design of the pacient detector. I turned all the brass on a lathe and the round bottom is plexyglass also. I added the diode later and its from an old military receiver also from the junk box.

The small black dial for the grounding cap. was salvaged from an old thermal resistance meter. Lots of great parts on those things. The ground and aerial posts are also original Atwater Kent parts also.

The coil slider coil is wound on a PVC form. I threaded brass rods to hold it together and the contact is made from a cabinet door bullet catch, Most hardware stores have them.

Last of all, The baldy phones were found at a local garage sale, I think brand new. Nathianel Baldwin radio works was located just 5 miles from my house. The building is still standing and is now converted into many small shops.

I think its great to receive a radio signal LOUD, Without batteries. Thanks again,

William.