Ruben's Maiden Journey of the Radio Shack Special

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In June 2004, Sir Ruben sent pictures and text of his maiden journey of the Radio Shack Special...

CONGRATULATIONS...Sir Ruben...my hat is off to you ! ! ! The many experiments you have done with the little jem, shows that just making the project verbatim...is sometimes, just not enough. Your continued quest of seeing what the little marvel can accomplish...is testimony of your laborless love in the world of Radio Frequency!

My father has always believed, as I do, that it is not the beauty of an image that makes it good...but the functionality of how it performs!

Below is Sir Ruben's own pictures and documentary of his successful maiden journey...

I had been looking for nice simple receiver projects both in books and on the Internet for some time. I had built some of them, but was generally dissappointed by the result. One day I discovered this little circuit called the Radio Shack Special on the site...http://www.somerset.net/arm/fm_only_lowtech.html and immediately decided to build one. There was only one problem...Radio Shack stores are not found in my country and I did neither have the MPF102 FET or any other FETs in my junkbox.

Faced with this problem, I went by train to the closest electronics shop I knew and bought two BF246 J-FETs. This J-FET, I believe, is almost the same as the MPF102 used by Patrick.

The few other components needed were already lying ready in my junkbox! Very rapidly I printed out the PCB layout for the project on a transparency and put it onto my home-made PCB exposure equipment with an empty copper board. I turned on the UV-lamp and waited 10 minutes. After first having the board in the developer 30 seconds and then in the etching solution half an hour...the board was ready. I was hurrying so much that the board had got the text that was on the layout...even if this wasn't the meaning!

Notice the word COPPER in the layout to the left. This showed up on my PCB...which is pictured below.

The big moment had arrived! Would the receiver work or not? I connected a small 9 volt battery and listened in the earphones...but nothing happened. I was disappointed. Was this another unsuccessful project? I disconnected the battery and took up a 12V-battery pack. And when I connected this time, I heard some noise! I turned the tuning capacitor a bit and then I suddenly got the local radio into my ears. Wow!!! How nice! It sounded like stereo...even if it wasn't.The sound was so clear that it was just like connecting earphones to Hi-Fi equipment. I was really impressed by this simple superregenerative design!

The day after I had finished the project I found out that there would be a big air-show in my area two days later. And since I knew that the airplanes and the airport communicated a few megahertz higher than the radio stations on the FM band, I found out that it could be possible to listen to them. But there was only one problem here...the planes' signals modulate on AM and the Radio Shack Special was a FM receiver. How could this AM demodulation be done? But then I found out something interesting. A superregenerative receiver can receive AM modulated signals as well as FM signals... and this receiver was a superregenerative one!

There was only one thing to do...and that was to experiment a little bit with the DRAIN coil. I removed some turns from it, and restarted the receiver.After carefully adjusting the capacitor I heard someone talking.This is sola information...Foxtrot..Transition level 8-5.......bla-bla-bla .

This was the continuously talking information channel at the airport. I then turned the capacitor forward and backwards...and soon heard someone talking again. This time I was sure that it was either a pilot or the tower at the airport. I then asked myself "Wasn't it harder than this to get airport signals into the ears?

I thought that one needed an expensive radio scanner to do this...but obviously this wasn't needed. I went to the airshow with my receiver in my bag and it became an amazing air-show. Both the amazing planes and this amazing receiver made impressions to me!

Thank you Sir Patrick! Even if these pictures show that I didn't make the receiver very pretty (bad soldering joints and ugly coils)...the receiver is working perfect. I connected one quarter-wave wire (60cm) to the antenna connection and the sensitivity became quite much better with this simple antenna.

In spite of that I now have made my first superheterodyne receivers, I still put the RSS on the table every now and then and listen to different things through it. It is still the most impressive little thing I have ever built.

Should you decide to venture out and make this unique little project yourself, do not hesitate to call upon me...to whatever questions you may have!