this would be a 2 piece unit with the modulator and oscillator indoors and an active final rf stage located remotely outdoors. it would use a gps or high stability crystal oven locked DDS oscillator feeding a balanced low noise op amp modulator stage and balanced buffer stage feeding a remote final rf stage consisting of balanced high voltage (class C,D,or E) mosfets feeding a rf isolation transformer, matching transformer/LPF which then goes into a Talking House Type Automatic ATU but something designed around a low loss and slightly higher "Q". it would also use a solid state low noise linear power supply rf filtered on the hot and neutral and would employ a 3 prong grounded plug. both indoor and outdoor units would employ aluminum housings for superior RF shielding. units should employ high tolerance components, fiberglass pc board and silver board traces. rf filtered audio inputs. the input to final would also be automatic power controlled to 100mW so no input adjustments would be needed.
any comments or additions to the design idea.
in theory this arrangement would have very efficient output stage and could be modulated to 150+%
There are some good ideas in this proposal. The idea of having everything except the final RF amplifier and tuning components indoors has appeal in terms of frequency stability and adjustments if needed.
Using a high efficiency final amplifier which has automatically controlled 100 mW power input could be a plus because the input power can change with weather conditions.
Neil
the gittings built unit i have is based around this type of design. except his is built designed and optimized for operation on 1700 khz only even it will go to other frequencies