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 HamSCI, 17 April 2025.
Presentation to PerthTech, 21 September 2024
This article was originally published in Amateur Radio magazine, Vol.93, No.4, 2025, pp 28-35. Copyright (c) Wireless Institute of Australia 2025