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April 10, 2009

Comments

Scooby214

Looks like it could be a good buy.

I haven't purchased a battery powered radio in quite a while, as I've been distracted by building crystal radio sets. Here are a couple of links to photos for the set I most recently built:

http://i711.photobucket.com/albums/ww119/scooby214/CrystalRadioSpring20091.jpg

http://i711.photobucket.com/albums/ww119/scooby214/CrystalRadioSpring20092.jpg

With my outdoor antenna and ground, I get surprisingly good DX with this set.

Jeffrey McMahon

Any man who builds his radios gets serious Man Points.

Ed

Great sets Scoob. I started with crystal sets too, even used a "cat's whisker" detector. My grand-dad was a pioneering radiophile back in the 1920's. He built his tuning coil from the proverbial Quaker Oats box... tuaght me about "bussbar" and condensers.

Scooby214

Thanks for the compliments. The two boards inductively couple to each other to make one radio. I built it with two dialspread settings, meaning when the switch is in one position the set tunes only the upper portion of the band. This makes it much easier to tune the crowded portion above 1200Khz. The wire used to wind the coils is 175/46 Litz (middle of the road when it comes to Litz wire). The ferrite core coils are coated with polyurethane. The tuning dials are actually mini DVD discs. I printed the scales on adhesive labels, cut them down to fit the discs, then coated them with clear acrylic so the labels would be protected. The knobs were NOS, originally intended for an old console radio.

The third board in the set is an inline wave trap that I had previously built. It is used to block a local flamethrower so I can DX a distant station on a nearby frequency. I built the wave trap using basic magnet wire, as the Litz wire is very expensive. While the ferrite core coils use 10 to 15 feet of wire each, the cylindrical coil uses significantly more wire. It would be expensive to wind with Litz wire.

I built the headphones as well, using sound protection muffs with large piezo elements inside.

Jeffrey McMahon

Ed, say happy birthday to your son for me. Jeff

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