QCX CW decoding

One of the aspects I’ve been surprised and impressed with is the quality of the CW decoding while sending. While playing with the onboard microswitch as a morse key I felt I needed to emphasise the length of the dashes for the encoder to resolve my sending. So I was pleasantly surprised at how well the decoding worked with a straight key and a sideswiper. These keys didn’t seem to impose the same timing expectations as the microswitch – which is odd because I believe they are wired across each other.

In any case, the decoder was able to present a pretty reliable rendition of what I had sent with both keys. Other systems I’m familiar with are only successful with keyer generated CW sent on a paddle. I’ve only seen sideswiper CW decoded by the Begali CW Machine which is a bit more expensive than the QCX but essentially built around a tiny AVR Butterfly.

Decoding in receiving on the QCX sometimes seems to be jeopardised by noise and static, although some quite clear and strong signals occasionally would not be decoded. I need to experiment more to do it justice and check what impact the speed adjustment has because ultimately it all must be using the same microcontroller code to decode the morse, sending or receiving.

QCX enclosure

One topic on the QRPLabs discussion group is the ideal enclosure for the little radio. The designer Hans G0UPL planned for all controls to be mounted on the small 10 x 8 cm PCB and provided for those who prefer to mount it in a protective enclosure.

As mounted on the PCB the shafts of the AF gain control and the rotary encoder are slightly different lengths and the tiny momentary switches are a long way from any front panel.

Part of the appeal of such a small radio is being able to show it off to friends so in one sense especially for this prospective audience an enclosure denies this pleasure – unless of course its transparent.

For the moment at least I think I may stumbled on to a neat solution. On the kitchen bench.

A suitably sized plastic container

The price is right and it’s tasty too!

Almost made to measure!

This way I can keep tweaking the radio and store it with a degree of protection. I started out with this 40m version with the pot and encoder connected by headers with a view to finding an enclosure later, but this solution feels a little neater and safer. And there may even be space for a battery.

QCX CW transceiver

I plan to use this category of my blog as a kind of sub-site to track the building of this delightful new transceiver kit from Hans Summers G0UPL and his QRP Labs. Since its launch in late August when all stock sold out in a day, sales of the QCX CW Transceiver continue at a pace that still surprises the developer as he prepares his fourth batch of 500 kits.

This is my QCX in action receiving and decoding signals during the Oceania DX CW contest this past weekend

It is a feature packed design focused on delivering an up to 5-watt single band CW transceiver. It includes built-in test equipment to be used during alignment and the QCX can be used as a WSPR beacon.

It’s such a compact design – the PCB is 102 x 81mm with a hard working blue 16 x 2 backlit LCD display – and with its tiny onboard microswitch that can be used a key, it should probably be renamed the QTX!

It boasts a long list of design features that seem amazing for the modest price of US$49. They include a Class E power amplifier, 7 element Low Pass Filter, CW envelope shaping free of key clicks, at least 50dB of unwanted sideband cancellation, a sharp 200Hz CW filter, Si5351A Synthesized VFO with rotary encoder tuning down to 1Hz, Iambic keyer or straight key option, CW decoder, displayed real-time on-screen, S-meter, Full or semi QSK operation, Frequency presets, VFO A/B Split operation, RIT, configurable CW Offset, Configurable sidetone frequency and volume and can be connected to a GPS interface for reference frequency calibration and time-keeping (for WSPR beacon)!

Also super impressive is the quality of the 138-page long assembly instructions that make Heathkit style instructions seem abrupt! Nothing else comes close to the thoroughness of this document. As well as getting a radio that works, Hans clearly wants builders to understand how it works and why he chose the components he did. Prospective builders can download it freely from his site.

Firmware for the ATmega328P microcontroller is up to version 1.00B and available from the QRP Labs groups.io group. It is not open source.

Sputnik 60 years ago today

One of the clearest memories of my childhood is being taken up our steep driveway to the roadside out the front of our house from where there was a commanding view of the western and the southern sky. Sixty years ago today the Russians launched Sputnik and it would have been a few days after this that my father took me as a seven year old boy to watch as the satellite passed over Sydney. He must have chosen a clear night because I do remember seeing it as a fast moving bright light. What was even more impressive was that then my father took me back inside and turned on our radiogram and switched over to the shortwave bands and seemed to know exactly where to tune the radio to pick up the beeping sound of the satellite’s radio signal. The Sydney Morning Herald has just republished its coverage which captures the local mood at the time.

A Russian 400 kopeks stamp showing the Sputnik’s orbit around the Earth

There are youtube videos online claiming to reproduce the actual sound of the sputnik.
Wikipedia links to this sound, but the authenticity of this too is challenged. From the wikipedia entry on Sputnik 1 I learned that there is a direct link between the satellite and the internet. The launch was brought forward to sync up with and maybe upstage the IGY – International Geophysical Year – which began in July 1957. The Soviet success and the US failure with Vanguard led to a major reassessment of the US approach to science & technology. One of the first responses from the US to this challenge to their technological and scientific prestige was to set up ARPA Advanced Research Projects Agency, later DARPA in February 1958. Australia followed the US lead. My generation saw a boost to science education. One of the scientists quoted in the Sydney Morning Herald report, Harry Messel, went on to edit the amazing ‘Science for High School Students’ textbook for high school which I devoured and almost memorised by heart.

The science textbook Harry Messel convened in the wake of the Sputnik crisis for Australian students.

I stumbled across a 55 minute long documentary on Sputnik ‘The Story of the Sputnik Moment’. It’s full of contemporary footage that really evokes the time from the US perspective. From this doco I learned that ‘Leave It To Beaver’ premiered on the same day! This was a popular program in our home – my parents thought I was a double for Beaver, but so did many others as I do remember there was a Beaver lookalike competition even here in Sydney! Anyway this video includes sound of the sputnik. It also echoes in reverse the current impasse with North Korea. There is almost identical footage of marching Soviet troops, admittedly with slightly less energetic steps. But the threat is the same. And the issues impingeing on the technological struggle such as the US civil rights fight remind us the civil war didn’t ever really end.

This is a flight-ready backup of Sputnik 1, on display at the Kansas Cosmosphere in Hutchinson, Kansas

If anything my father seemed more impressed by the achievement than fearful for what it might mean about global nuclear war, but really what would I have known as a seven year old!?! I do remember he had a friend at his work, Tullochs a railway rolling stock and steel building material manufacturer, who was a radio amateur. It was most likely this ham who gave Dad the info he needed to tune into the signals, although I believe it was probably included in newspaper stories. This was probably the same man he took me along to meet after I had started building radios as a 12 year old. I think his name was Bob and he lived in Ermington or thereabouts. I don’t remember his call but I do remember that he had built all his gear and operated exclusively CW on 20 metres into a dipole in his modest backyard, to keep in touch with friends back in the UK where he’d emigrated from.

What I know now as well is that 1957 coincided with the best radio propagation conditions ever. It was the high point of the best solar cycle, so the few feet of copper wire hanging in the air as an antenna would have had no trouble pulling in the 1 watt signal from Sputnik. And of course background interference would have been minimal compared to today. So maybe I’m mostly nostalgic for the quieter and yet more lively radio conditions of times past.

What’s great about this memory is that it’s clear my father had a strong sense of the significance of the event and my potential interest. Even though he wasn’t a technical person he was quick to sense my interests and encourage them. Maybe it would have been hard to miss noticing the young me in the backyard hammering away at a piece of metal downpipe trying to fashion a rocket nose cone! From this day on I remember being given How and Why Wonder Books about rockets and science, and avidly collecting cards from Nestles chocolates for their ‘Adventure in the Sky’ album.

Cover of ‘Adventure in the Sky album published by Nestle to encourage kids like me to buy more chocolate bars to collect images of planes and rockets!

From reading about the launch it’s apparent that what we probably actually saw was the larger remnant of the R-7 rocket that followed the satellite into orbit. It was first magnitude compared to the Sputnik’s sixth magnitude size and brightness in the night sky. That knowledge however doesn’t dim the excitement I remember.

Falling squid poles

Or how Stephen just realised the error of his thinking for the last few years…. again.

Recently I’ve been thinking more about the perennial problem of using squid poles as antenna supports – the fact they all too readily collapse into themselves. This is probably more of an issue with permanently set up poles, but it also can waste valuable operating time in the field. Insulating tape works for a while, but it removes protective paint from the pole and is pretty messy.

Only this past weekend I had set up my 7m squid pole near the small lighthouse at Henry Head on Botany Bay. The winds were so strong and constant I could have got away with not bothering to tether the distant end of my end fed half wave antenna, as it was blowing horizontally from the tip of the squid pole – just like the original end fed Zepp antenna would have looked behind the airship that gave it its name. But of course just as I was about to answer someone’s CQ, it collapsed!

For some years now – at home – I have used an idea that I think originated from Peter Bogner of DX-WIRE in Germany where he recommended using a cable tie nestled inside a square section rubber tube to secure the sections to each other. I have always assumed the cable tie and rubber sleeve are positioned at the overlap point between two adjacent telescoping sections of the squid, that is around the lower (and larger diameter section). This approach leads to a more resilient antenna pole which is more likely to survive windy weather, but it is by no means guaranteed to stay up indefinitely.

This is the rubber profile from DX Wire acting as a stop

I have just checked his site, specifically the page about this “rubber profile” and realised I have been using it incorrectly. His intention was to use these as “stoppers” and as a cheaper adaptation of the rubber padded stainless steel clamps of the larger Spiderbeam poles (see below) for shorter telescopic fibreglass poles.

There is a pdf file linked to from this page which visually confirms the use of the rubber profile and cable ties as “stoppers”.

This is the MAB34 support plate that can be used to guy say a 7m squid pole

Peter Bogner’s DX-WIRE also sells a handy “support plate” that can be used on our 7m poles as a way of attaching guy lines to the pole at the handy height of about 2m from ground. It sells for 3.5 Euro including VAT.

I have been forced to think more about this topic after needing to re-assemble my collapsed 10m squid pole almost every week or two.

I happened to be looking at the Spiderbeam site and also looking at the DIY info to help build your own version of the spiderbeam antenna. I have also looked at their own more robust version of the squid pole, the Spiderbeam pole available in 12m and 18m!

One of the rubber covered clamps used to keep the Spiderbeam 12m pole upright

The device of choice these days appears to be the pipe clamp or what the British call the Jubilee clip. The beauty of these clips is that they can be tightened and later if necessary untightened. Seems a little more sound than using up tens of long heavy duty cable ties every time I work on the pole. The clips also make it more practical to dismantle the pole in case of particularly high winds. This would be even easier if pipe clamps with butterfly handles were used in place of the screws.

The clips are available in stainless steel and feature a worm gear driven by a screw thread to adjust the size and pressure of the clip. Spiderbeam offer a set of clips for their Spiderbeam telescopic towers, 11 for the 12m pole. They are sold along with sections of rubber to be used underneath the metal band of the clip to protect the pole.

I have read elsewhere a recommendation to insert the metal band inside a piece of heat shrink for extra protection.

For me though recently, the main question about these clips has been where precisely should they be installed on the pole.

The Spiderbeam company’s advice is clearly to install them not at the overlap but around the thinner upper section to prevent it slipping into the lower section.

Simply put one clamp at the very bottom end of each tube segment and tighten the clamp. Here it will act as a stopper and prevent the tube from sliding downwards into the next bigger tube segment. The rubber padding is made of a thick flat rubber band, protecting the mast against any damage from the clamps.

This advice is quite a surprise to me. It makes sense only if it’s assumed that the pole has been assembled in the normal (?) way of extending the sections and tightening each of them before installing the clips.

On reflection the approach of using the clips more as a stop than a clamp makes more sense. I have always had qualms about compressing the outer tube against the inner tube when they are both rather rigid. The pipe clamps are able to exert quite a deal of compression but that would be unnecessary in the recommended ‘stop’ mode.

My next task is to measure the various diameters of each and every section of my 7m and 10m squid poles from Haverford’s and my 12m Spiderbeam pole, so I can obtain the most appropriate sized pipe clamps for them. TTS Systems, the Australian distributor of Spiderbeam, sells the clamp set for A$44. You can buy direct for 15.55 Euro but postage I think is a lot more.

UPDATE: I purchased the clamp set from TTS Systems. They were easy to assemble. The kit is the set of clamps, a 1.2m length of 3mm thick by 12mm wide rubber strap and black heatshrink to hold the rubber in place.

The completed set of clamps for the 12m Spiderbeam pole

In case you’re wondering – the pipe clamps / jubilee clips sizes for the 11 sections are:

40-60mm x 2, 32-50mm, 30-45mm x 2, 25-40mm, 23-35mm, 20-32mm, 16-27mm, 12-20mm, 10-16mm

As you can see from the photo you need to open the clamps out to install the protective rubber strip and the heatshrink. I suspect the larger, lower clamps are doing the most work.

I installed them on my Spiderbeam pole on a site in the southern highlands. It’s holding up a vertical for 40m, one of a number of antennas to be used in some upcoming contests. Returning after four weeks and strong winds, three of the lower sections had collapsed, so those clamps were tightened. I may have been too tentative/cautious on the initial installation.

Here is the 12m Spiderbeam pole enjoying a clear day in the southern highlands!

Oscilloscope music

The other day I was pottering around Facebook and stumbled across an amusing story via BBC News I think about a young couple who had decided to set themselves the challenge of visiting every one of the over 2,500 railway stations across Britain. I later discovered it’s connected to a Kickstarter project and has a website http://allthestations.co.uk. Reading some of the comments to the video – always a risky activity – I discovered a reference to the videos made by Geoff Marshall (of the same couple) exploring the secrets of the London underground and another youtube video – via https://www.youtube.com/user/geofftech2 – where he talks about cassette tapes. He also has a website at http://geofftech.co.uk.

In the comments to this clip there were a number of pointers to another youtuber who focuses on old analogue technology called ‘Techmoan’ – https://www.youtube.com/user/Techmoan. One of the first videos of his I watched featured what Techmoan described as his holy grail of 1970s consumer electronics – something that featured both Nixie tubes and an oscilloscope to visualise the music – a bizarre old silver SAE hi fi amplifier you can see on https://www.youtube.com/watch?v=ZkCIdufSGS8.

About half way through the video he demonstrated the way the small oscilloscope worked. Normal music resulted in an animated but pretty fuzzy trace jumping about the screen. Then he put some different audio into the amp and the oscilloscope which resulted in regular geometric images appearing on the small screen. Quite amazing! I was aware of the neat regular waveforms that can be created with different frequency ratios on the X and Y plates. The Australian ABC’s logo was created by using a 3 to 1 ratio many years ago. But what I was seeing on the screen was lightyears beyond that.

He got a lot of comments pointing him to resources on oscilloscope music and a follow-up youtube video had pointers to a number of clips and sites, most notably Jerobeam Fenderson’s site at http://oscilloscopemusic.com.

a random screengrab from one of Jerobeam Fenderson’s piece for oscilloscope music – planets

You can view a number of his pieces on his Youtube channel – https://www.youtube.com/user/jerobeamfenderson1.

Techmoan also provided links to an Oscilloscope Emulator for Windows, Mac & Linux https://asdfg.me/osci/ which works on my Mac and a Reddit Oscilloscope Music Page https://www.reddit.com/r/oscilloscopemusic/ with further links and info about this bizarre art form.

Jerobeam Fenderson also offers a program to create oscilloscope music called OsciStudio via his website.

Back in the loop

My main project for at least the last 12 months has been building a solid magnetic loop antenna and its companion automatic loop controller. I’ve been roughly tracking its progress at my magnetic loop antenna project page on this blog.

As usual, life has got in the way, but I want to get back on track and complete the project. To start pumping some RF current through it again, over the weekend I spent a short time playing with the loop on WSPR on 40, 30 & 20m. The tests were too brief but they certainly confirm that the loop is capable of transmitting a signal in spite of the fact the loop is only half a metre above ground and surrounded by metal garden furniture, a steel framed awning and gutters.

I used the WSPR Beacon android app to control my transmitter. There was some discrepancy (tens of Hz) between the actual output frequencies on the app and those shown on WSPRnet. I also found that tuning the loop to each WSPR frequency using the iP30 antenna analyzer was easy and the KX2 gave lower SWR figures.

The brief test became an exercise in understanding theWSPRnet results taking into account propagation and loop orientation which was aligned north-south.

This map view combines all 20 spots of the 1W VK2RH transmissions from grid square QF56oc. The first test was logged at 2017-05-07 01:36 UTC. (I’ve trimmed repeated info from the chart below to improve its fit on the page.)

Time MHz SNR Drift Reporter RGrid km az
 05:24  14.097001  -15  1  VK4ALR  QG56fk  1151  356
 05:24  14.097016  -26  0  VK4TDI  QG62lm  733  14
 04:48  10.140109  -22  0  VK4TDI  QG62lm  733  14
 04:48  10.140094  -23  0  VK7TW  QE37pc  1057  198
 04:48  10.140091  -17  0  VK6XT  OF86td  3086  261
 04:40  10.140095  -27  0  VK7TW  QE37pc  1057  198
 04:40  10.140090  -4  0  VK3WE  QF32se  547  216
 04:40  10.140090  -22  0  ZL1RS  RF64vs  2069  101
 04:40  10.140092  -15  0  VK6XT  OF86td  3086  261
 04:40  10.140091  -16  0  ZL3GA  RE66ho  2130  126
 03:18  7.040121  -24  0  VK3BAL  QF22mc  711  230
 03:18  7.040134  -7  0  VK3AXF  QF33fn  516  235
 03:18  7.040135  -18  0  VK4MOB  QG62ol  734  16
 03:18  7.040130  -18  0  VK3DXE  QF21nv  720  228
 03:18  7.040128  -12  0  VK2TPM  QF56of  14  0
 03:18  7.040129  -14  0  VK7DIK  QE38cu  918  207
 01:36  7.040183  -16  -1  VK3AXF  QF33fn  516  235
 01:36  7.040177  -16  -1  VK2TPM  QF56of  14  0
 01:36  7.040184  -24  -1  VK4MOB  QG62ol  734  16
 01:36  7.040179  -21  0  VK3DXE  QF21nv  720  228

40 metres favoured north-south, while 30 metres was literally an all-rounder and 20 metres was too brief. These results probably say more about propagation than the loop, not to mention the heavy lifting done by all the reporter stations extracting my down to -26 or -27 dB signals from the noise! Impressive all round!

I wonder how many people are using the Sotabeams WSPRlite antenna tester device. Certainly looks tempting, especially for longer term antenna evaluation.

In any case, the main purpose of today’s exercise was to re-start the loop project. The To Do list includes

  • building & installing the SWR bridge into the loop controller,
  • deciding on the best way to couple the stepper motor shaft to the tuning capacitor shaft,
  • and wiring it all together with appropriate coax and control cables.

US exams at Wyong

About midway through January, I heard via a Sunday morning WIA broadcast that a group of ARRL Volunteer Examiners was offering to hold exam sessions at the Wyong Field Day at the end of February.

I passed my original amateur license exam here in Australia almost 40 years ago. My AOCP (Amateur Operator’s Certificate of Proficiency) says I passed a test on 21st November 1978. (That was probably the date of my second or third attempt to pass the morse at 10 wpm test.)

For the exam, I also had to answer questions about radio regulations and to demonstrate “a knowledge of wireless telegraphy and wireless telephony and electrical principles”, I had to write a number of essays about things like neutralizing a valve (tube) power amplifier or how a superheterodyne receiver works. A lot has changed since then. New technology like software defined radio and the internet.

After I heard that local hams were conducting US license exams here, my first resolution of the year was to pass the US exams for all three levels.

I was surprised that I was able to do this. All the FCC required was an online registration of an FRN (an FCC Registration Number) using a US address which was easy enough to obtain without having to pay a monthly fee. Also for the US, there is no license fee and licenses have a term of ten years.

With just on six weeks to prepare I planned to work sequentially through the three levels, spending more time on the hardest level, Extra. With no time to spare I ordered Kindle versions of the license manuals for all three levels. I also downloaded copies of the freely available complete question pools for each level. The exams are objective tests based on random selections from every part of all of the ten main exam topics – 35 questions for Technician and General, and 50 for Extra.

The license manuals essentially re-arrange the hundreds of disparate questions into a more or less flowing narrative about how to be a modern ham radio operator.

As I worked my way through the manuals I would mark up the questions and answers in my copies of the question pools and make notes if necessary to explain the answer.

The information in the manuals was very well presented and manageable and digestible. I loved the way liberal amounts of ham radio wisdom about operating practice was added to the mix. It was really like having your own personal Elmer guiding you through the intricacies of aspects of the hobby that previously were unclear or were new to me.

Best of all for me the study process demystified a lot of the mathematics of electronics and set me on a path to better understand what after all is the basis of the ‘magic’ of radio. I love the fact that the Scottish mathematician Maxwell concluded radio waves must exist, just from the maths, many years before they were actually discovered or produced by Hertz and others.

The ARRL web pages supporting the license manuals has links to a range of other resources including a page of references that pointed me to a really brilliant site which sets out to systematically (and enjoyably) explain the advanced maths to those whose school maths didn’t quite reach those dizzy heights, like me. It’s highly recommended if you want to delve deeper.

I’m happy to say I passed all three exams. I received an email from the FC about two weeks after the tests. There was no real need to do it, but it was a personal challenge – a little like voluntarily doing a driving test again, times three. It also turned out to be a convenient way to calibrate and update my ham radio knowledge.

The session was well organised and afterward, one of the VEs demonstrated how he uses his US call by connecting via remoteham.com on his iPad to a contest-grade station high in the hills in New York state. Amazing and fast! At rates around a US$ a minute, this must be a good way to turn a remote location into a source of revenue to be earned from the hordes of hams living in cities with a high level of local electrical noise.

Hygge DX

Just read about Scandinavian versions of untranslatable concepts (like German’s gemütlich or Portuguese’s saudade) at Quartz.

One example is the Danish word hygge (pronounced ‘hooga’)…

There’s no direct English translation for hygge, but the word evokes both coziness and togetherness. “It’s not just cozy with a blanket and a glass of wine,” Kurtz tells Quartz. “It’s also interpersonally cozy—so having a few people with you talking about issues and things you care deeply about. Having some candles lit, maybe a nice warm drink in your hand. Feeling safe and content.”

The Norwegian equivalent is koselig.

Psychologists working at the University of Tromsø have found that those further north in Norway have more positive wintertime mindsets. Kari Leibowitz wrote a piece for The Atlantic explaining how people flourished there during winter.

It all helps explain the popularity of Dxing and SWL as a group activity as written about here a while ago.

I just checked and four of these Norwegian radio friends spent another week or so over October and November DXing, and eating and drinking the best the planet has to offer enjoying their QRM-free QTH with views out over the Barents Sea! Analysis of their reception recordings continues over here.

That’s a sustained radio bliss!


The Smartlock is an accessory for my SGC SG-239 HF Smartuner, and other ATUs they make. It can be bought ready made or built.

There are indicator LEDs that signal status (TND, l ‘Z’, 2:1, PHZ, FWD, Auto & Man) on the lower section of the PCB of the SG-239 but they are only visible near the unit. As they recommend mounting the unit in a weatherproof container and as close to the feed point as possible, it’s unlikely these will be useable except in testing and servicing.

For reference – here are the indicators and connections on the transceiver end of the SG-239:

B.I.T.E.* Status LED Descriptions – *Built In Test Equipment

TND This LED will light when the tuner has found an acceptable match. It will remain lit until conditions have changed which will cause the tuner to find a different match. (i.e. A new transmit frequency has been detected, or tuner has been reset.)

L ‘Z’ This LED shows the status of the antenna impedance. When lit, the impedance is 50 ohms or less. When off, the impedance is greater than 50 ohms.

2:1 This LED will light when the VSWR is greater than 2:1. It will extinguish when VSWR is less than 2:1.

PHZ This LED indicates the status of the antenna reactance. When lit, reactance is inductive. When off, reactance is capacitive.

FWD This LED indicates the presence or lack of RF power from the radio. When transmitting, the LED will light to indicate RF is being detected. In receive, the LED should be extinguished.

OTHER All LEDs will blink on and off at a rate of 2Hz to indicate the tuner was not able to find a valid match.

The LEDs are very small and quite faint and almost impossible to see on a sunny day.

As the ad below indicates the Smartlock provides two controls that can be used remotely from the tuner and close by the radio – allowing the operator to lock or stop the ATU constantly retuning as the load changes and to reset which forces a retune the next time a signal is transmitted.

The Smartlock also indicates if the ATU managed to tune the antenna and if the lock is on. The lock can be invoked when the antenna is to be used for receive or when there are too frequent changes in the physical environment of the antenna such as when mobile and passing trucks or going under bridges….

Installation requires normal coax and a four conductor cable for power and control.



Catalog #54-63
The SmartLock provides two external controls for the SG-230/237/239 Smartuner. The locking function prevents retuning despite changing antenna loads. The reset function forces the coupler into a retune cycle the next time a signal is transmitted. Tune and lock status is indicated by one green and one red blinking LED. Supplied with 9 feet (2.5 metres) connecting cable. For use with SG-230/237/239 couplers manufactured after July 1, 1993, only.

From the product number, this seems to be the unit described above, on the SGC shop page at http://www.sgcworld.com/shopsite_sc/store/html/page5.html

This is the official circuit from the manual for the SG-239 (http://www.sgcworld.com/Publications/Manuals/239man.pdf)

Its simplicity and the cost of the assembled unit have inspired a number of people to roll their own.

The colour code of the cable to the Smartuner appears to be:

TND = Green,
HLD/RSET = White
+12V = Red
Gnd = Black

Simplified SmartLock

Phil Salas – AD5X – decided to remove the components making up the voltage regulator part of the circuit.

“I wanted to build a SmartLock to use with my SG-239. After studying the SmartLock schematic, I couldn’t figure out why SGC put in the transistor and zener diode. The ST-TNE input on the SG-239 is just a 1.5K resistor to an open collector transistor to ground. So I eliminated Q1, R3, D1 and C3 on the SGC SmartLock schematic. My final circuit is shown below. I used a DB9S connector to interface with the SGC tuner (I attached a DB9P to the tuner interface wires), and a PowerPole interface for 12VDC. This way I could use a standard DB9 extension cable as necessary for interfacing between the tuner and SmartLock. I used ultra-bright LEDs (3000mcd or so) to provide plenty of visibility.”

Phil Salas’s build of the Smartuner

There is another variation by Luca Molino IV3ZNK that can be seen at http://www.xluke.it/2016/07/28/smartlock-per-sgc-239

This uses a tiny PCB available on Italian eBay from a seller who wanted 50 € to send one to Australia!

I worked out a way to use a scrap of veroboard to hold the two capacitors and one of the resistors and to manage the wiring between the base and the panel of the enclosure which is probably more efficient and certainly faster. As well I noticed that the PCB seems to be designed for a different kind of DPDT switch where the centre poles are not in the centre!?! So I can add the satisfaction of saving whatever Euros I would have ultimately paid to the greater satisfaction of having nutted out the layout of the veroboard scrap…

Luca used the simplified circuit by Hans Nussbaum DJ1UGA which appears to have in turn have some subsequent input from OE7OPJ (who by the way has a very interesting website at http://www.qth.at/oe7opj/).

This circuit can also be seen at http://www.qth.at/oe7opj/homemade-smartuner-lock.htm.

The components required are

2 x 1k5
2 x 100nF
Green LED
DPDT switch
SPST MOM pushbutton

Pretty neat!

text of the italian site:

L’accordatore automatico SGC-239 indubbiamente è un gran bello strumento. Si collega e funziona ottimamente con qualunque radio (HF) semplicemente utilizzando un cavo coassiale e una fonte d’alimentazione a 12 volts. Non è particolarmente esoso di corrente e anche in utilizzo SOTA non va a gravare sull’autonomia giornaliera. Ne ho trovato uno usato sui soliti canali nazionali ad un prezzo decente e non mi sono fatto scappare l’acquisto. Accorda davvero di tutto gestendo potenze da 1,5 a 200 watt. Ottimo per il mio Yaesu 817, ma altrettanto utile per le “normali” radio munite dei canonici 100 watt.  Per poterlo però utilizzare al meglio, si rende necessario l’acquisto di un interfaccia che permette di resettare o bloccare lo stato d’accordo del SGC-239. Tale interfaccia (SMARTLOCK) si trova però in vendita a quasi 100 euro, decisamente troppi per 2 condensatori, 2 resistenze, 2 led e un paio di interruttori. La prima idea è stata quella di prendere lo schema presente sul manuale dell’accordatore e realizzare su basetta forata il circuito. Cosa questa realizzabile, ma che avrebbe dato un idea di “precarietà” a tutta la realizzazione. La scelta a questo punto è ricaduta su un mini circuito stampato realizzato con maestria da Danilo Cramaglia (lo trovate su Ebay come utente Martelloman), che partendo dallo schema elettrico mi ha consegnato quanto riportato in foto:

The SGC-239 automatic tuner is undoubtedly a very nice tool. It connects and works well with any radio (HF) simply by using a coaxial cable, and a power source to 12 volts. It is not particularly power hungry and even practical to use on a routine SOTA outing. I found one used on the usual national channels at a decent price. It really suits around handling power output from 1.5 to 200 watts. Great for my Yaesu 817, but just as useful for “normal” radio equipped with 100 watt “cannons”. 

But in order to make the best use, it is necessary to obtain an interface that allows you to reset or block the status of the SGC-239. This interface (SMARTLOCK), however, is for sale at nearly 100 euro, far too much for 2 capacitors, 2 resistors, 2 LEDs and a pair of switches. The first idea was to use the circuit in the tuner’s manual and build it on perforated board. While this is feasible, it could give an idea of “insecurity” to the whole creation. Instead I chose a mini PCB made with skill by Danilo Cramaglia (Ebay-user Martelloman), which, starting from the wiring diagram handed me what is reported in the picture:

I plan to use this wiring arrangement for the 4 pin plugs, socket and line.

1 Red – +12V
2 Green – Tuned
3 White – Hold
4 Black – Ground and -12V

As well Philip Storr VK5SRP describes his version at http://www.philipstorr.id.au/radio/seven/accessories.htm.

SGC Smartlock control

In the hand book to the SGC SG237 Auto Antenna Tuner there is a circuit for an interface they call the SmartLock and it allows some manual control over the AATU and more importantly, it indicates when the tuner has tuned successfully.


JH2CLV has documented his build.

These photos (from http://www5a.biglobe.ne.jp/~jh2clv/newsmartlockmaking.htm) give an idea of the layout which uses an external “chocolate block” connector for the 4 core power and control cable.

Case used is a plastic case – HA1593-KB of TAKACHI.

The main parts are as follows.
② 4P harmonica terminal (Chocolate block)
③ 6P toggle SW – actually a DPDT switch
④ push button SW
⑤ LEDs (red and green)
⑥ resistance (150Omu-330Omu)
⑦ capacitor (optional)
⑧ 9V3 terminal Reg (7809)
⑨ plastic case (TAKACHI / HA1593-KB)
⑩ wiring material


Also http://www5a.biglobe.ne.jp/~jh2clv/smartlockmaking.htm has details of changes – design and layout…

(2) inside the box configuration

The shielded 4 core wire is clamped in the cable tie through a pull through bushing. The case uses a diecast aluminum box TD 5-8-3B (55x30x80) by TAKACHI. The front of the enclosure has the Normal / Lock switch (2-pole, double-throw), the Tuned LED (Green), the Locked LED (Red) and the Reset switch (Make contact). It includes the three-terminal regulator. The bypass capacitors on the circuit diagram are omitted here.

(3) box overview and operation

Once tuning is complete the Tuned LED (Green) glows. If the Normal / Lock switch is pointing to the right, the Lock side, the Lock LED (Red) is lit and fluctuating SWR, etc. does not cause automatic re-tuning.

If the switch is set to the Normal side, normal operating conditions prevail, the SG-239 will automatically start tuning if SWR or the band is changed.

If you press the RESET (red) button, the ATU will re-tune.


Also check http://g3ynh.info/atu/sgc230.html for detailed description of using the Smartuner with a balanced antenna.

For some good ideas about how to protect the SG-239 see http://dg6hd.darc.de/html/sgc-239.html. He uses a large-ish electrical junction box and includes windings on toroids…

>So here is my effort successfully completed today…

I used the simplified circuit by Hans Nussbaum DJ1UGA and the front panel layout of Phil Salas AD5X. I managed to squeeze everything into a compact package – a small die cast aluminium enclosure 64 x 58 x 35mm which Jaycar sell for $9.95. And that was the main cost. Everything else was on hand.

I’ve yet to label the panel, but the green LED indicates a successful tune, the red LED is on when the switch is in the Locked position, and the push button switch is the reset. I used 4 pin sockets and line plugs to connect to and power the Smartuner. And I used a DC socket to supply 12V power. I had planned to use power poles but decided that would not fit comfortably in this small enclosure.

The ATU is housed in a plastic lunchbox which can be protected by a larger rubber waste paper bin as recommended in the SGC manual.