I was in a gas station one day and they had these cheap watches on sale($4.99) for Christmas.The watches were junk, but they were in a nice thin gauge aluminum case with lid. My eyes widened as I thought...I could put a radio in that!!! So I bought one, threw the watch away and kept the box.
The Swiss Sport was about to be born...
The Swiss Sport is based on the Tiny Tornado with PTO by KA8MAV. It's basically a Pixie with a (P)ermeable (T)uned (O)scillator. Which means a variable inductor is used for tuning instead of a variable cap. The inductor uses a brass screw for the slug. Brass is used because of its permeablity rating.
A piece of RG-174/U connects the PTO to the radio. I'm going to install a wall of double-sided pcb between the to circuits to provide shielding and then feed the coax thru a hole.
Not quite finished yet. She still needs the output filter section and a little more LM386 wiring.
...Not so bad. A good layout helps. It should kinda flow. This is my favorite method of construction. I love knitting ckts together. I guess you would call me an "Old-Skool" Builder. Make solid connections first, then solder. Keep all connections short and direct. Always figure out your mounting scheme before installing parts.
The inductor can easily be made and is very forgiving. I used a 0.5" long piece of a BIC™ pen body epoxied to a piece of circuit board. A nut is soldered to the backside for the screw. By using another board with a nut, smoother tuning can be achived.
I'll eventually cut the head off and install a knob for tuning. After trashing that mounting hole, I decided it was better to punch the holes into the box rather than trying to drill this thin material
Aren't small radios great!
...did I say small? This is the T37-6 output filter toroid
Goofy Loves Chasing QRP DX !!!
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