Scratch Built Transmitter in 1968

By Bob Mosley

 

I shared this old photo with Steve Belknap showing a transmitter I scratch built in 1968 when I was in 9th grade and he asked if I would write up something about it.

 

Bobs TX

 

I built the 3 channel transmitter from a schematic in MAN (Model Airplane News).  I bought the electrical components from Shanks & Wright, Milo and Western Radio (they were located on Kettner Blvd and India St. and are all gone now). I measured the lead spacing and drew a PC board trace pattern on quad paper.  I etched the PCB with ferric chloride after covering the copper with electrical tape and cutting it with a #11 and straight edge, then drilled the holes after etching.

 

 

The stick was a Rand that I mounted two Allen-Bradley pots to and the third channel was a reed switch. The Tx box was an aluminum LMB project box I got from one of the electronic stores that are no longer in existence. I didn’t have a nibbler or broaching tool so I had to drill and file the trim tab slots. The tacky looking wood finish is shelf paper. The Tx was 27MHz, note the center loaded antenna. The crystal alone was larger than a modern thumb drive.

 

When the Tx was completed I was surprised it actually worked. The receiver and servos were kits offered by Royal (and they were a Royal PITA, but I’m OK with that because I learned how to solder tiny stuff building those things). Then 72MHz became the new ‘air’ frequency and it was a lot safer than sharing 27MHz with CB operators.  At around that same time Heathkit came out with radio kits so I built those to get into 72MHz.

 

During college I worked in the evenings at Lindberg field as ramp crew for Delta Airlines (DC-8’s). I studied mechanical engineering with a minor in electrical engineering. That, along with my hands on experience with RC gear, helped my career in aerospace and defense designing and manufacturing electronic hardware used in aircraft, spacecraft and missile systems.

 

By the mid 70’s and after college I phased out of RC and into motorcycles, sports cars and motor racing. After 10 years of racing I got married and raised a family. One day in 1999 I was on Sea World Drive and happened upon the SEFSD field. Everyone was friendly and it was interesting to see the advancements in electric flight. Thanks to SEFSD I got back into RC and have enjoyed several forms of RC flight from gliders to turbine powered jets, however most of my model planes are electric powered.