Category Archives: QRP

2016/17 rollover party on Mt Disappointment VK3/Vc-014, and the christening of ‘Summit Prowler Two’

I left my plans for 2016/17 rollover late, and when I checked sotawatch alerts 24 hours out, there must have been 15 summits manned. From lunchtime on I was due at my brother’s QTH in Doreen, north of Melbourne. So I chose Mt Disappointment, which is an hour’s drive from my place and 45 minutes drive from the lunch destination. This gave me time for a leisurely activation on the picnic table near the summit. This was also to be my first attempt to activate a summit on 30 meters CW with the newly finished Wilderness SST rig.  It all went to plan. With 4 CW QSOs on 30 meters bagged, I switched to 40 after rollover for a bunch of hunt-and-pounce QSOs. Here’s a video that offers a taste of the CW and SSB signals heard and worked.

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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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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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Mt Donna Buang (VK3/VC-002) and Mt Ritchie (VK3/VC-003)

A clear winter’s day was forecast on August 5th 2016 and with arrangements made I headed out early to Mt Donna Buang VK3/VC-002 with plans for Mt Ritchie VK3/VC-003 afterwards.  I left Melbourne’s eastern suburbs by 0710 and arrived at Donna Buang around 0845 to a frosty, clear, cold and calm summit, distrubing no fewer than 5 lyre birds on the final few kilometers before the car park.  A bonus for getting up there early was spectacular morning sunrays cutting through the mountain mist.

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Mt St Leonard VK3/VC-006 for the VK1 SOTA QSO Party 2016

The VK1 SOTA QSO Party is in its fourth year.  Mountain Goat Andrew VK1AD ex 1NAM does a fine job of promoting it and rallying VK1s onto hilltops.  On Friday 5th August he posted that there were 19 planned activations recorded at SOTAWatch involving activations across VK1, VK2, VK3, VK5, VK7 and ZL1.  It worked out that if I left early for a nearby summit and kept moving I could join the party on Mt St Leonard VK3/VC-006. Mt St Leonard is not much more than an hour’s drive from the eastern suburns of Melbourne.  I left at 0710 and arrived at the car park just over an hour later.  On the Yarra Glen-Healesville Road I passed the morning balloon departure.  I was on the summit by 0830, plenty of time.

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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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FYBO 2016 at Kangaroo Ground

Sunday was the inaugural Freeze Your Butt Off (FYBO) context, devised by Ian VK5CZ to encourage portable (parks and SOTA) activity during the SOTA winter bonus period. The timing could not have been better for freezing one’s butt off, as an Antarctic blast of cold air swept up the east coast of Australia on Friday, just two days earlier, resulting in record low temperatures and snow falls down to 500 meters from Bathurst to Ballarat. Melbourne shivered through the coldest June day in almost 20 years on Friday with temperatures as low as 2C on Friday night. It was 4C at 9am Saturday. This is unseasonably cold.   I considered activating Melbourne’s nearest SOTA summit Mt Dandenong VK3/VC-025 (2 points) but my time was so short I opted for old favourite Kangaroo Ground which gives a clear take-off in all directions, has facilities, and can be reached in 30 minutes.

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