Wooden Box Radio

 

This project grew out of something that was being sent to the dump. It seems like ages ago the XYL got a present for Christmas that involved burning some candles to which you add these nasty scents and the whole kit and caboodle is called Aroma Therapy. Well as with many of the useless gifts it got put in the back of the closet where finally after many years the XYL ordered me to Clean the Closet! Well imagine my surprise when I discovered that the Aroma Therapy stuff came in a wooden box with two small side pockets.

When I saw the box my mind drifted back some 50+ years ago when I remember seeing an article about a small hollow state (battery powered tube) transceiver built into a small wooden box. I guess the idea of taking radios on camping trips and outdoor hikes has been around since the early spark days. Well I always had that idea tucked into the back of my mind. But the big problem was where to find a wooden box. Shazzam! Here was that wooden box staring me right in the face.

Not wanting to totally start from scratch I took an existing 20M CW transceiver that I built several years ago and simply repackaged the radio to fit in the box. The original radio can be seen here.

The repackaging took about two days and what you see is the finished product. Basically the radio is a transmitter and receiver and the only common elements are the VFO and the TR switch. The transmitter puts out three watts.

The receiver employs a broad band RF amp, the mixer is a TUF-1, followed by a 2N3866 post mixer amp. The output of the 2N3866 is fed first to a 3 DB pad and then on to a homebrew 4 pole 9.0 MHz crystal filter. The IF amp is a MC1350 followed by the Product Detector/Carrier Oscillator which is handled by a NE602. the Audio Pre-Amp is a NE5534 and the Audio Amp is an 8 Pin LM-380. During transmit a VNK10 MOS FET is used to mute the MC1350 utilizing the AGC input, Pin 5.

The transmitter uses a 9.0 MHz crystal oscillator that is keyed by a PNP transistor. This is fed to another NE602 where it is mixed with the 5.0 MHz VFO. The output of the NE602 is fed to MPHS10 to amplify the output and then on to the Band Pass Filter. The driver following the BPF is a 2N5109 which drives a 2N2075 to about three watts output. TR switching is done with NE555. The keying is automatic break-in. The receiver is not totally muted during transmit and it is possible to hear the 9.0 MHz oscillator being keyed. This provides a convenient means of setting an appropriate offset and to provide side tone during transmit.

Keying is clean and no back wave. My first contact was with KD5RRD, John in Los Alamos, New Mexico. My report was 559. Roughly speaking that is about a 1300 mile hop from my QTH which is 50 miles NW of Seattle, WA. My second contact on 10/01/2009 was with Toni, CT1GND at Nabais, Portugal at 2120 UTC on 14.060 MHz. Toni was 579 and my report was 559. QRP works!!!!

My 50 year old dream has come true!

Pete N6QW