Category Archives: SummitProwlers

SP-8: a homebrew 28MHz SSB transceiver for a UR3LMZ 144MHz transverter

Ten meters or the 28MHz band is showing glimmers of life from sunspot cycle 25. Even so, its not an obvious choice if you want to build a portable SSB monobander and have lots of contacts. But 28MHz is the IF of choice for VHF and UHF transverters. After noticing the 6, 2 and 70cm transverters available on eBay from the workshop of UR3LMZ and the good reports from buyers, I cooked up the idea to build a 28MHz ‘transverter IF’ transceiver, to be paired with one or more VHF or UHF transverters.

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SP-X, a pocket rig for the CW activator in a hurry!

I’ve long been interested in compact and fairly minimal SSB and CW rigs with good performance. I’m not into bells, whistles or menus. Menus are for restaurants! When hiking, walking or bouncing around summits I want to minimise things that are not absolutely necessary, things that can go wrong. Less is more when it comes to a transceiver for portable work.

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Something old, something new: A four-band 5W/50W SSB/CW transceiver (‘Summit Prowler 7’)

‘Summit Prowler 7’ is my name for this scratch-built multiband SSB and CW transceiver. This rig 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.

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Pocket-sized homebrew 40m CW QRPp/QRP transceiver

In May 2019 I activated Mt Dandenong VK3/VC-025 with my latest homebrew rig. It was a CW only activation, five QSOs completed, but while I was handing out 599s, the reports coming back to me from the chasers were well down. Over the next few days on OZSOTA (the VK SOTA discussion group) several chasers made comments to the effect that they could hear other VK3s but nothing much from me. When regulars Tony VK3CAT, Ron VK3AFW and Gerard VK2IO reported the same thing, the evidence for a problem at my end mounted.

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Summit Prowler 6: A pocket-sized SSB/CW transceiver for 80, 40, 30 and 20m

Peter DK7IH is a master of compact homebrew transceivers. I’ve been reading his excellent blog where he chronicles more than half a dozen homebrew HF transceivers and related projects. Most are compact SSB superhet transceivers with digital VFOs, AGC, metering and PAs in the range 5 to 50 watts. A few of these rigs are just so remarkably tiny I wonder how he has the persistence and patience, not to mention how he gets them stable. With Peter’s fine examples in my head, I started daydreaming about a compact SSB/CW transceiver, hoping to go a fair bit smaller than my slightly chunky attempt at a hand-held from last year.

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A scratchbuilt G6LBQ BiTx ‘Walkie-Talkie’ for 40 and 20m SSB/CW

After completing a 6-band SSB/CW QRP transceiver (Summit Prowler IV) I found myself thinking about a more compact QRP SSB/CW rig for SOTA, with two of the main day-time SOTA HF bands (40/20m). The design driver this time was to try a different ‘form factor’ — I wanted a rig with a narrow and long case, such that it would easily slide inside a backpack, and on a summit sit vertically against a rock or be hand held. All my SOTA rigs so far use both front and back panels for connections and controls, so they need to sit level on a horizontal surface. As most rocks or tree stumps are low, you can’t easily read the display. Some designers get around this by putting the display on the top of the box, a sensible adaptation but one that makes the rig look like a flounder. Because I spend a lot of time building and using these radios at home on the shack bench as well as on a summit, I wanted a design for use in both situations.

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‘Summit Prowler IV’ — Homebrew 160m to 17m QRP SSB/CW transceiver for portable and SOTA use

‘Summit Prowler IV’ is a scratch-built six-band SSB and CW transceiver, designed for portable and SOTA activations. It is based on Leon VK2DOB’s MST3 (Minimal Sideband Transceiver, third version) from 2016, with alterations to support multiple bands, my Arduino-based digital VFO/controller and keyer, and a few extras to support portable operating. The transceiver is a conventional single-conversion superhet with 12MHz IF and an si5351 and Arduino Nano-based digital VFO. This project comes after having done more than 50 activations with my 2013 MST Mk I kit radio on 40m SSB. This rig has performed well on 40m SSB (and CW after I added it) and has launched my interest in SOTA activating, turning me into an occasional weekend ‘summit prowler‘.

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Homebrew 160 meter AM/CW transmitter receiver

The VK 160 and AM SOTA event (1st April 2017) provided the deadline pressure needed to complete this build. The rig is a separate transmitter and receiver, so seeing as there are no shared modules, I shall call it a trans-receiver rather than transceiver. The designs for both transmitter and receiver are by Drew Diamond VK3XU. See Drew’s Projects Volume 3 book for full details, available from the WIA or RSGB. I posted details of the 160m AM receiver when I first built it, a year ago. At that time I also built the transmitter and power supply. I got the transmitter going but blew up the PA FET (BUZ90). During the long wait for replacements, I shelved the build and moved onto something else. Now, thanks to SOTA, it is finished.

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A scratch-built 30m CW transceiver (Wilderness SST 30)

The Wilderness SST was designed around 1997 by Wayne Burdick, N6KR of Elecraft fame.  It was kitted (by Wilderness Radio) and sold well to excellent reviews.  On eHam the rig scores 5.0/5 from 33 reviews.  It is an exercise in minimalist design, and there is obvious lineage to be seen in how certain aspects of the SST design found their way into the Wilderness range of QRP radios, such as the way the receiver is coupled to the PA output and monitors the transmitted signal, and the audio-derived AGC.  It was respected among the QRP crowd in the USA (it appears in a list of QRP kits on Wikipedia, most of which are from US sources) but was not widely known here in VK. Fortunately, all of the resources and more to build this transceiver are easily found online.

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‘Summit Prowler One’: A homebrew 7MHz SSB QRP transceiver for SOTA

It all started 18 months ago with the completion of the MST400, a 7MHz SSB QRP transceiver in kit form. I’ve used this 40 meter 5 watt monobander for 34 SOTA activations to date.  It is the radio that appears in every one of my activations in this blog till this weekend. Following the pleasing performance of the MST receiver I wanted to scratch-build an SA612 based radio, to see if I could reproduce the performance of the MST400 but with a few changes to make it even better for activations.  I christened this radio the ‘Summit Prowler One’.  Summit Prowler?  Last year my First Harmonic and friends went through a huge ‘Magic The Gathering‘ stage.  MTG is a mythical strategy card game full of weird characters with strange powers.  When I first saw the MTG Summit Prowler card it occurred to me that there was a link to SOTA there, somewhere.  First Harmonic has moved on to other games, but my first Summit Prowler has been born!  Here it is, in its first incarnation, on the bench, around May 2016.

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