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Crystal Radio #78 — with a Contra-Coil

Dave's crystal radio #78 main picture.

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This radio has been previous published in the December 2010 and January 2011 issues of Monitoring Times Magazine. This page will show only the highlights of my receiver.

The Basis Of This Design

Hello radio friends. My last 77 sets have been a combination of pretty simple radios up to the overly complex projects. In other words, there is something there for everybody.

Everyone remembers their first crystal set they built. I do, and that was over 50 years ago! But my kid-built sets were kind of rustic to put it nicely. In my later adult years, I decided that I would build the crystal sets that I would be proud to display, which I have done it on this website. While many builder would just take a couple snapshots of their radios, there was no information available for others to reproduce the radio.

My #78 radio was meant especially for the homebuilder to reproduce the radio themselves. This is why I took my radio to Monitoring Times Magazine for first publication. The article, split into two issues, has very detailed descriptions. I did this as I considered the article to be a stand-alone publication effort and therefore everything had to be contained within the article. It was my greatest publication effort.

This radio is based on my last radio effort, my #77 set. The main difference is the use of a contra coil to boost the high end of the band efficiency.

My dx radio also uses a dual coil tuning system, consisting of an antenna tuner section, as well as a headphone matching transformer. This end-to-end attention to performance detail is what makes this a worthwhile project.

All the parts are available for this project, but not as a kit. Just individual parts. If you have trouble locating some of them, I may be able to show you where you can get them. Mike Peebles at Peeblesoriginals.com may have some. The hardware is available from McMaster-Carr.

Here is another view of this project, as well as the schematic. Good luck with your homemade crystal radio.

Dave's  Handmade Crystal Set #78 Rear View
Crystal Radio #78 Schematic

Crystal Radio #78 Schematic

73 and good crystal DX. Dave - N2DS

Closeout Radio Parts Available