It was a homebrew receiver built from parts that had been part of lab experiments that came with a radio-tv repair correspondence course that my father had taken in the early 1950's. It was, in fact, watching him solder and work on assignments that first stirred my interest in radio.
After he completed the course, the materials, including parts and printed lessons were stored away in a closet and when he figured I was old enough to know what to do with them, I was given the boxes of goodies. I was eleven years old at the time and already DX-ing with table radios and had begun poking around in them, trying to improve performance and hoping to get something going that would tune the short wave bands.
Among the boxes of parts and papers there were chassis with holes punched and chapters on designs for various circuits used in superhet receivers. It was a matter of putting the pieces together to get the receiver transferred from sections of lessons to being an operating radio. There was one experiment that detailed making an H.F Converter to tune from about 6-18 MHz that would convert those signals to be tuned in by a regular broadcast receiver tuned to just above the high end of the broadcast band. That design became the front end of my first receiver to tune higher than the 160 meter amateur band ( I had previously gotten a standard broadcast receiver to go that high by pulling out the tuning slugs and loosening the trimmer capacitors as far as they would go).
With the help of the head tech and owner of Lawson's Radio and TV repair shop I managed to get the thing assembled and working. I am not sure how many times I had the chassis in the basket of my bicycle for the two mile ride from our house to his shop, but with his help and parts from his parts stash and junk box, the radio became a working reality.
The basic radio was a six tube superhet that tuned the broadcast band with one RF stage and one IF stage. It had an AC/DC power supply with a double section capacitor and choke filter. The RF stage was modified with a double tuned input aligned to 1650 kHz with another fixed tuned circuit on its output. The HF converter consisted of a 12K8 pentagrid converter circuit with its own filament transformer supply that lifted B+ voltage from the basic radio. The converter had its own two gang variable capacitor with the original radio set up fix-tuned to 1650 kHz.
|Under chassis wiring of the receiver. The HF converter chassis is to the left.|
Closer top view showing the chassis top near the tuning capacitor for the base BCB portion of the receiver. The coil to the left of the larger variable capacitor is part of the fix-tuned 1650 khz IF circuit. The two silver cans are the electrolytic power supply filters. The clips on the rear of the chassis are the connections for antenna and ground. The small transformer on the rear of the HF converter chassis is for filament voltage for the 12K8 converter stage. The other six filaments are in series and operate like a conventional AC/DC receiver.