40 meter 100 watt Transmitter

The 40m receiver was complete and it wasn’t long before the old girl was beginning to look forlorn. It was obvious she needed a mate. Hmmm....perhaps something tall, dark, and handsome? Nope. She would have to settle for something short, wide, and solid state.

This transmitter can operate on the 40m band without time limit at an output power level of 100W carrier on CW and RTTY, 100W PEP on SSB, and 25W carrier on AM (100W PEP with 100% modulation). The final amplifier stage runs a pair of Motorola MRF150 high-voltage RF power TMOS-FETs in push-pull configuration, biased for class AB linear operation. Although the PA stage is capable of substantially more power, limiting the output to this level is an act of kindess to a pair of very expensive transistors and provides a “standard” output level for driving legal-limit amplifiers.

Some highlights:

You can download the schematics (200K) for this transmitter, viewable with Acrobat Reader. The ten pages of schematics were produced using VISIO Technical. February 28, 1998
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