SOTA is great portable operating concept, and many activators like to pair it with another challenge — working DX from mountain tops, CW only, 23cm or low power. My interest is homebrew. Some years ago (2015) I started my line of homebrew QRP rigs, known as ‘summit prowlers’. These rigs reinvigorated my love of homebrewing and radio craft, and gave me some great activating moments on southern Australian summits in summer and winter.
Note that these rigs are all scratch built one-offcreations for my use only, not kits or attempts to create a transceiver that others can reproduce. Having said that, they are derived from openly accessible proven designs and can be reproduced in part or full by a moderately experienced maker. If you’d like to discuss any aspect of these radios post a comment on the appropriate page.
This is a compact four-band pocket CW transceiver with fixed frequency channels on the 40, 30, 20 and 17m SOTA CW calling frequencies. It is modeled on the KD1JV MTR-5 but with my own preferrences in the Arduino , filtering and control areas of the design. It uses three BS170 FETs in parallel to deliver up to 5 watts in a class E configuration, amazingly miserly on battery power! Full write-up with video and schemativs here.
Summit Prowler 9 (SP9)
This rig is a compact five-band SSB/CW rig in a walkie-talkie styled case, optimised for SOTA/portable, and made to slide vertically into the pack, with 5 watts SSB and CW power. This project spanned 18 months from initial planning to completion. A full description with schematics is here.
Summit Prowler 8 (SP8)
A compact 28MHz SSB-only monobander that incorporates a 2m transverter in the same case. This rig provides two new bands for SOTA fun, 10m and 2m. A full description with video and schematics is here.
Summit Prowler 7
This SSB and CW transceiver, SP7, was designed for operating portable in a sunspot minima — it covers four of the most popular portable, Parks and SOTA bands (80, 40, 30 and 20m) at a power level of 5 watts, but with an in-built switchable 50 watt power amplifier, so that you have the option to call up the extra power if the going gets rough. The rig weights in at around 1 kilogram or 2.2 pounds, about the same as an FT-817, and is similarly sized. It’s a rig for a wide range of portable situations, and is equally at home on the shack bench. Full description with video and schematics here.
Summit Prowler 6
I was inspired by the many compact scratch built HF transceivers by Peter DK7IH. He has taken the crafting of radios to a new level, combining physical, mechanical and RF design and construction and delivering tiny rigs that meet respectable performance for analogue radios. Summit Prowler 6 was the result, another multiband SSB/CW superhet rig, this time based on DK7IH’s Micro42 design, and using my Arduino script and si5351. For a detailed description, video and kicad circuit, click here.
Summit Prowler 6b
Back around April 2019 some of the VK SOTA people came up with a proposal for a VK QRPp SOTA Challenge, in Spring 2019 (Sep to Nov). The Challenge was to reward QRPp power levels, so I wanted to come up with something in the 200mW range, with an IRF510 afterburner for when no contacts are made. This pocket rig uses the old Motorola MC3362 radio on a chip from 1996, and a K1EL PIC-based single-IC keyer. The rest of the design is conventional. Description with schematic here.
Summit Prowler V
Summit Prowler V is a hand-held 2 band SSB and CW rig (2 watts on 40 and 20m) with built-in push-button keyer. The concept picks up on the ‘walkie talkie’ form — hand-held, light, built in keying buttons and microphone, able to be cabled up to battery and antenna quickly, but without compromising on receiver quality. I achieved the first two activations with this rig at Sugarloaf Peak near Buxton and Mt Strickland, Yarra Ranges in October 2018.
Homemade #QRP SSB/CW #hamradio transceivers for the fields, parks and mountains #SOTATweet
Summit Prowler IV
Summit Prowler IV is a 6 band SSB CW rig (5 watts on 160 to 17m), my most versatile homebrew rig to date, with built-in keyer and a number of other ‘improvements’, I christened it with a pile of SSB and CW contacts at Mt Buffalo, Falls Creek and Mt Hotham in Victoria’s Alpine region in February 2018. I’ve been impressed with how well this SA621 based simple superhet works. No IF gain, no RF amp, just Gilbert cell mixers and audio stages.
Summit Prowler III
The annual 160m and AM VK SOTA activation day in April 2017 provided the incentive I needed to finish off a project I’d been working on for a while, a small 160m AM/CW transceiver (Summit Prowler III). This rig combines a superhet receiver with 470kHz IF and three-pin MK484 AM detector, and another VK3XU designed 160m AM transmitter, using a 50 watt kit audio amplifier, crystal oscillator and BUZ90 class D PA for 30 watts of CW and AM. I activated Mt Gordon near Marysville with this rig and a 160m inverted-L antenna, working VK2s and 3s on nearby and distant summits and home stations.
Summit Prowler II
Next came Summit Prowler II a Wilderness SST monobander for 30m CW. This little rig was designed by Wayne N6KR of Elecraft fame, and was very popular around the turn of last century. I added a K1EL keyer and an IRF510 QRP afterburner for 5 watts CW and made quite a few nice VK and ZL contacts. Pictured above at Mt Tabletop, Bogong High Plains, Feb 2017.
Summit Prowler I
I returned to scratch-building portable SSB QRP transceivers after many years with Summit Prowler I, a build of Drew Diamond VK3XU’s Twin Crystal Filter (TCF) transceiver. It’s a 40m superhet with 8.867MHz IF and a 16MHz SuperVXO, with SA612 mixers and a 2N3866/IRF510 PA, with modifications. Shown above at Mt Strickland, Yarra Ranges, September 2016.