Category Archives: homebrew

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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QRP by the Bay, Saturday 5th November 2016

QRP by the Bay is a regular homebrew, experimenter’s and portable ops show-and-tell hosted by Peter VK3YE at Chelsea Beach. This was my second event, which followed in the now established tradition.  This year it attracted about two dozen people and a variety of projects appeared on the tables. The weather was not ideal, it was very windy and cool, but the squid poles went up nonetheless.  Peter’s video of the event is here, and another one of the 160 meter bayside portable QSO here.

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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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Mt Little Joe (VK3/VC-027) and Mt Strickland (VK3/VN-030)

Sunday 23rd October 2016 promised to break a cold and wet spell in Victoria’s Spring weather that had deposited heavy rain, hail and snow down to 800 meters.  The night before, a bunch of keen activators had braved the weather to participate in a VK-ZL-G-Eu joint activation timed to capitalise on grey-line propagation.  Hats off to those who did go out because Melbourne’s weather was atrocious and a summit was about the last place most people would have wanted to be.  The next day, Sunday, dawned dry.  I considered going up to Lake Mountain for Federation Range but the snow cams showed a fresh coating of powdery white stuff, not enough to ski on but plenty enough to make it cold. What I really wanted was to christen my recently completed homebrew 7MHz SSB rig, codenamed ‘Summit Prowler One’.  The design and build story for this project in another post.  Mt Little Joe promised a good activation experience and a fresh mountain walk.

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Superhet crystal mixing schemes

Homebrew superheterodyne receivers/transceivers using a computer crystal ladder filter, BFO and  VXO offer the combination of simplicity and stability.  The key to this receiver pattern is the VXO.  I know VXOs are so ’90s, and that I should embrace digital and start banging out DDS VFOs with Arduinos, eBay AD9850 cards and AdaFruit si5351‘s.  I will soon, I promise.  In the mean time I just want to explore computer crystal mixing schemes a little longer.   Scratch-building a DDS VFO necessitates some new practices, such as getting the script you’ve picked from dozens online to compile and download to the controller, for the particular combination of display, Arduino and DDS chip in use.  I’m not saying it’s too difficult, I’m just observing that it isn’t trivial, and if you get stuck you may find yourself limited in your options to unpick it.  Crystals, on the other hand, are real, physical things, remarkable for their sharp resonant characteristics.  And these days they’re almost literally a dime a dozen.

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2.4GHz Wifi corner reflector 

First Harmonic (FH) was getting patchy wifi coverage to his desktop computer in his bedroom.  The obvious thing would be to invest in a new multiband wifi modem/router, one of those things that looks like a UFO with spiky antennas for its multiple bands.  But the situation presented a good opportunity for some basic UHF antenna experiments over this short unlicensed duplex data link. Discussion of the popular Cantenna suggested lower performance than many have claimed due to the small size of Pringles/Milo cans at 2.4GHz. A repurposed satellite TV dish of diameter 1.2m or more seems to be the best option.  Not having one, and needing a solution that would not turn FH’s bedroom into a junkyard, I opted for a homebrew corner reflector based on one of the many online designs.

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Artisan Printed Circuit Boards

I have been hand-making printed circuit boards since I was a teenager.  In the late 1970s I started with ‘proper’ PCBs, hand-drawn, hand-drilled, then painted with resist (bituminous paint) thinned with turpentine and applied with a tiny brush to form the copper traces, drilled holes on the copper side, etched in Ferric Chloride, cleaned and sprayed with a clear enamel to stop tarnish.  This was the way all circuit boards looked at that time, including commercially made ones in kits, and those inside transistor radios, digital clocks, televisions and ham radio transceivers.

Sometime in the 1980s I tried a ‘copper side up’ board, dispensing with the drilled holes, free-hand drawing on the copper side, painting and etching, then soldering the components directly to the copper pads. I’ve been making them this way ever since.

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A 160 meter homebrew superhet receiver for AM

On the workbench at the moment is the receiver part of a 160 meter AM trans-receiver. So called because it will be a separate transmitter and receiver in the same box. Both designs are from Drew Diamond VK3XU’s Radio Projects Volume 4 (available to WIA members here or GQRP Club members here). I have built one of these receivers before, and it performs well as an AM receiver. The VFO is stable enough for AM and usable for SSB with the accompanying 470khz BFO. The lack of selectivity in the IF doesn’t really matter on 160m because the band is never crowded, other than you do of course hear all detected audio frequencies. Even so, the listening experience is fine for such a simple receiver.  And it sounds just like those AM receivers with barn door selectivity that I used as a young bloke.


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Peter VK3YE on QSO Today

David VK3KR tipped me off over the long weekend that Eric 4Z1UG interviews Peter VK3YE this week for QSO Today, Eric’s weekly ham radio interview podcast.  Eric interviews notable people, and people who just do interesting things in the hobby, and has a global audience. This is another recognition of Peter’s remarkable work over the years with all things QRP.   Eric’s interview primer:

The local city dump was the source of parts for Peter Parker, VK3YE’s first ham radio projects. This humble beginning made Peter one of the most prolific contributors of videos and articles on the art of amateur radio. Peter builds his own gear, operates QRP from the local beach, and gives valuable advice on how to be a successful operator. VK3YE is 4Z1UG’s guest on QSO Today.

In the podcast Peter talks about early days in VK6, working with two AM receivers to resolve SSB in the 1980s, finding the balance between simplicity and capability, and some other interests, including a novel way of illustrating Melbourne’s public transport timetabling.  From Eric’s promotion email:

In this week’s QSO Today with Peter Parker, VK3YE, Peter discusses how he converted the railroad schedule to sound, in Melbourne, Australia, where he lives and works. The schedule was designed to sync the trains and buses to minimize passenger wait-time in transit. A very clever idea, especially since he explains, in the podcast, where the rhythmic patterns were regular, the transit times were more efficient.

I have learned from my QSO Today guests to be open to new ideas that they introduce to me. Be sure to check out the link to CYMATICS: Science Vs. Music – Nigel Stanford – YouTube Channel, mentioned in the podcast. In the video, the artist, Nigel Stanford uses sound from a speaker to modulate physical objects to create some very interesting visual effects. Exposure to different art forms opens my mind to solutions to other problems by causing me to think more creatively, in all areas, including ham radio.

Eric has 88 interviews on his site, 80 of these are American hams, of the remaining 8 Peter is the only VK. Congratulations Peter!


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EMDRC Hamfest 2016

Sunday was the annual EMDRC Hamfest. I had a table with David VK3KR.  It’s the second time David and I have shared a table at this event and on both occasions we were individually clearing out saleable shack stuff that had been previously liked, appreciated and admired, even loved, kept for a rainy day, cached to be dug up acorn-like in our antipodean equivalent of a snow storm… in our hour of homebrew need.  Of all our accumulated goods this was stuff which had passed the interest threshold. None of it was without some kind of appeal and most items had a potential use.  But all of the items had fallen down the priory list relative to other stuff.  In a ham’s middle years there is a dawning that ones’ days as an active key (as opposed to a silent one) will not go on forever, and that there are more potential shack projects than one mortal life will allow one to complete.  On that basis, some items just have to go.


David VK3KR at our table.

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