*********This page is under
construction*********
Beware of Errors!
I
recently constructed and tested a pair of Transverters for
Thru-the-Earth
Voice Communications. I made modifications to Ian Drummond's
design
to increase the receive dynamic range. I retained the original audio
power
amp IC design, but added a second amplifier in parallel with the first
to increase the output power. The Design can be used as-is for 45-185
KHz
SSB or FM, but would not produce much AM output due to the high peak
power
demands. The IC's work excellently below 100 KHz, and with
reduced
output to 185 KHz. For FM, it would be better to use a high efficiency
switching power amplifier rather than this linear design. For optimum
performance,
each winding of the three transformers (L4, T1, T2) should have a
reactance
of 5 to 10 times the impedance of the circuit it is connected to, ie a
reactance of 250-500 ohms for the 50 ohm windings.
So far I have posted the
block diagram, schematic, and parts list for the Transverter. I will be
including construction hints, photos and antenna designs in the near
future.
I did not use PC boards for my prototypes. I have antenna design
software
that I will be using to predict antenna impedance and radiated fields,
etc.
