|The October 2013 issue of Electric Radio Magazine includes my article showing how to convert a basic "All American 5" broadcast radio into a simple 2-watt 75 meter AM transceiver, named "All American 75." MCRN members as far as 300 miles away have heard its Heising-modulated QRP signal.
The AA75 conversion consists of adding an external power supply to eliminate the hot chassis shock hazard and building a simple crystal controlled transmitter using a 35L6 that replaces the original rectifier tube in the series filament string. Re-tuning the receiver from the BC band to 75 meters provides about the same performance as an S-38 type receiver which is good enough to hear any station that can receive the AA75s QRP signal.
I was motivated to try the AA75 conversion after finding an AA5 radio with a hopelessly broken plastic cabinet in an antique shop for $5. As a result, this rig is housed in a homebrew cabinet made of scrap wood and plastic (note how the dial has been carefully calibrated for AM operation!) I hope others will be motivated to try similar conversions and with their own innovations. Since the basic AA5 circuit was used by hundreds of manufacturers, the AA5 was possibly the original Open Source Design!
Unfortunately, a couple of errors crept into the 35L6 transmitter schematic that appears on page 19 of the article, and I urge anyone wishing to give this idea a try to use the following corrected version of 10/13 instead of the one published in ER.