Useful documents by Peter Hall (VK6HP) and others
Fully integrated PA using a G0MRF push-pull Class D module, integrated power supply and doubler. The PA system is driven at 475 kHz from a 1 mW (0 dBm) source.
Very fast, low jitter comparator based on an LT1016 IC. The comparator is particularly useful in single-ended and push-pull Class D/E amplifiers. It enables a push-pull PA module to be driven directly from a 0 dBm source, eliminating the usual frequency doubler and divider. Input dynamic rage is at least 20 dB and complementary output square waves are highly symmetrical. With good high-frequency construction techniques, observed near-in PA phase noise is ~10 dB better than with typical CMOS logic elements in common sine-square conversion schemes. For compatibility with 50 ohm systems, mount a terminating resistor at the input BNC socket.
All original material is copyright by Peter Hall unless otherwise stated
July/August 2024 QEX article by Peter Hall (VK6HP) describing the VK6MJM LF/MF station at Manjimup, Western Australia.
Reprinted with the permission of the ARRL. Copyright ARRL.
The Adventures of Little Bertha (Coming Soon)
Little Bertha is the new VK6MJM 2200 m loading coil. The 2.6 mH coil is 410 mm in diameter and wound on a stiff cardboard former, with about 90 turns of PVC covered, 7-strand, building wire. The former was coated with shellac and winding taps were made using a very simple loop and cable tie method. The intention was to see how well a coil made using basic techniques and common materials would perform relative to more optimized inductors. In the end, a Q of about 400 was measured: not stellar, but adequate for the intended application.
VK6HP tests an eBay RF power amplifier with potential LF/MF and lab applications.
Presentation by Peter Hall (VK6HP) to PerthTech 2024.