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Gallery: Wall-Hanging Transmitter

My friend Pierre K9EYE is a visually-impaired ham who would like to add to his ham radio experience by making a transmitter himself.   Considering the difficulties involved with conventional chassis construction gave me the idea of returning to a breadboard form and when Pierre heard about the idea he named it the "Wall Hanging" transmitter because it could hang on the wall instead of taking up space on his operating desk.   

The frame is made of oak, with a plywood bottom that is covered with galvanized "tin" sheet metal from the furnace aisle at the home improvement store.  This stuff takes solder easily and provides a good RF ground.   The circuit is my "HT-4U"  six watt Heising modulated AM transmitter that appeared in my my Electric Radio article, just repackaged and moved from 75 to 40 meters.    Octal relay socket bases and Euro-style screw terminal barrier terminal blocks take care of most of the interconnections, and the few solder connections needed are to the metal ground plane.   You can basically assemble this transmitter with a screwdriver!  

Conenctors, the PA tuning capacitor, and a few other components are mounted to a metal bracket and a clear plexiglass cover is fitted over the top to prevent contact with any high voltage connections.   Large diameter holes are cut to provide clearance and ventilation for the four vacuum tubes.

The power requirement are 300VDC at 100mA and 6.3VAC at 2A for filaments.   I suggest using one of the cheap eBay HV boost converters to generate the 300 volts so that HV is only present in transmit mode - safety first!

VIEW Image #1

W9RAN's "Wall Hanging" transmitter for K9EYE

Posted: 10/14/2019 (ranickels)
VIEW Image #2

Another view of the 75 meter version

Posted: 10/14/2019 (ranickels)
VIEW Image #3

Breadboard wiring method

using Euro style terminal strips and octal relay sockets

Posted: 10/14/2019 (ranickels)
VIEW Image #4

HT4U Schematic

the basis for the Wall Hanging Tx

Posted: 10/14/2019 (ranickels)