Class E AM transmitter- 40M

JohnFreeman

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I finally finished a Class E AM transmitter kit (about 1"x 3") with a homebrew modulation transformer fed with a 50 Watt Chinese audio amp (12.50 postpaid). The metalwork to add switches, relays, power connectors , BNCs, boards, etc took forever but I didn't end up with any extra holes (there is one that's oversized however)

Makes a very nice 100% AM modulation waveform @ about 140 V ptp (maybe what, 40 watts PEP...I don't have my calculator) .

Winding one 40 foot length of wire for the secondary and 30 feet for the primary onto a T200 toroid for a modulation transformer takes some patience

The waveform below is a 1Khz tone into a 50ohm load at 7.290 Mhz. Vertical axis is 20v/div.

Fun stuff!
John



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Nice. Haven't done anything like that since some college laboratory classes and even then it was far less roll your own.
 
Thanks.... I'll try and get a shot of the box. The transmitter board is about 1"x3", the whole rig is about 5x7". Class E is really slick, with efficiencies on the order of 85-90%. I get about 13 watts of carrier out for 1.2- 1.3 amps of 12V in .
 
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