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 thing is homebrew. A few years ago (2015) I started my line of homebrew QRP rigs, affectionately 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-off muppet style rats nests for my use only, not kits or attempts to create a transceiver that others can reproduce. All 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. Thanks for reading!
Summit Prowler I
I returned to scratch-building complete portable SSB QRP transceivers after many years with Summit Prowler I, a build of Drew Diamond VK3XU’s Twin Crystal Filter (TCF) transceiver, a 40m superhet with 8.867MHz IF and a 16MHz SuperVXO, with SA612 mixers and a 2N3866/IRF510 PA, with modifications.
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.
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 (CW) with this rig and a 160m inverted-L antenna, working VK2s and 3s on nearby and distant summits and home stations.
Summit Prowler IV
The latest in the series (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 and Mt Hotham in Victoria’s Alpine region in February 2018. This will become my primary SOTA rig for the foreseeable future.
And the next Summit Prowler…
What’s next? I’ve been thinking about a smaller Summit Prowler — with 3 pluggable bands — probably 80, 40 and 20, SSB and CW, using an ADE-1 receive mixer, two MOSFET IF stages and a simple AGC circuit, SA612 product detector and transmit mixer, 1496 balanced modulator, and a low height LCD on an 40mm (not 50mm) angle chassis. A pair of RD16HHF1s should give 10 watts across all bands on 13 volts from the 4S LiFePO pack. With a bit more care in the design of the boards, I reckon I can make this one about three quarters the size of SP-IV, whilst still using predominantly homebrew boards and thru-hole components, and without losing my eye-sight or my sanity!