Thursday, November 23, 2017

Archive of early technical magazines

American Radio History is a fantastic archive of early electronics, technology, sound recording and broadcast magazines. Mostly UK and US. It includes some classics including Byte, Popular Electronics, Modern Electronics, Wireless World, and some educational titles.

I saw this on Roger G3XBM's excellent blog that is (mostly) about ham radio but I find the occasional diversions most entertaining. Roger wants an IC-7300 for Xmas I see.

Tuesday, November 21, 2017

Tuning 40m at a low noise location near Dorrigo

What a pleasure it is to tune the 40m band at a location where the only noise is the occasional "tick tick" of electric fences. Here's a bit of a tune around this week.

We need some remote receivers at places like this. Unfortunately there is no mobile reception at this property.

Monday, November 20, 2017

Low RF noise location - near Dorrigo

This week I'm spending a few days at a very low noise location in northern New South Wales near Dorrigo.

Yesterday I tuned around 40m and experienced S0 noise. There were some stations in Victoria and Tasmania coming through well. Tonight I will try to join the Home Brew Group's net. Here is my squid pole hanging off a stake. (I'm told there are much better stakes, normally used for electric fence supports, available for about $4 - will investigate).

The local paper, the Don Dorrigo Gazette, here is printed with the old letterpress system and looks amazing.

Internet here is pretty slow so I won't be posting much.

These posts, seen below with the orange loop at the top, are widely used to hold up electric fences. They have a convenient foot hook for pushing them in to the ground.

It's lovely here, audio and electrically quiet. The only sound on radio is the clicking of electric fences - how ironic.

Saturday, November 11, 2017

Blog hits a million page views

A milestone today, the page views on this little blog has just hit one million. This blog is really a personal notebook where I write little posts that I can find again later to remind me how to do various things.

The first post was on October 12, 2006 back in the days when email spam was still a problem. Before this blog I had another, rather too serious blog. I found that I'd set the bar too high. Posts were essays and I couldn't keep it up. I was foolishly thinking too much about the audience. Giving that up and just posting notes to myself has done the trick.

The blog is never a chore and many times I've searched for how to do something and found my own blog post from the past. I fear that social platforms like Facebook are becoming the owners of our writing and much like GeoCities will some day disappear with all of that content. Arguably a blog on Google's Blogger suffers the same drawback but I hope that Google is more likely to keep it up.

Thanks everyone for visiting, for comments and for getting in touch.



Friday, November 10, 2017

Comparing antennas with WSPR

The new end fed antenna has obviously higher signals but also higher noise. The question is.. which antenna is better?

I now have three antennas that work on 40m (7MHz). The real test of an antenna, at least on receive, is the signal to noise ratio, and WSPR is a great way to measure this. I've set up three receivers, with three computers, all running wspr with the following call signs.
  • VK2TPM/1 is a half G5RV into an FT817
  • VK2TPM/2 is the new end fed into an IC7300
  • VK2TPM/3 is my old dipole fed with open wire feeder into a KX3
At the time of this first post, I'm surprised to report that my half G5RV is significantly better than the dipole or end fed for most reception.

Reception of VK2RG who is 48km away.

Reception of VK3AFE, who is 718km south of me.

Reception of ON7KO who is 16,732km away.

Comparing antennas is not simple. Each antenna is directional so performs better for stations in certain directions. Local stations are received quite differently to remote stations where signals come in from above. Some antennas pick up more local noise than others.

WSPR is a great tool for antenna comparison. Is there a better way to plot the data?

Update: I'm wrong

I think my analysis above is incorrect. Looking at all data over a 24 hour period it's clear that the big dipole receives more spots overall, which is a good measure of overall receive performance.

For what it's worth, here's the average received signal to noise ratio, spot counts and total distance of all spots received. (I don't actually think adding all S/N db figures makes any sense).

So in the end the dipole I think performs better even though signals (and noise) are higher on the end fed. John, VK2ASU, correctly points out that I haven't attempted to tune the end fed for 40m properly and that may well improve it.

Monday, November 06, 2017

Built an end fed match box

At QRP by the harbour I put up a dipole for 40m and John VK2ASU put up an end fed antenna which seemed to work better. My dipole was held up in the centre on a 6m squid pole and the ends drooping down to ground stakes at each end.

John's end fed went straight up to a squid pole and then over to a nearby tree. He cleverly used a bottle filled with water to throw the end up there (to save weight {although he also carried a lead mallet for the ground stake}). In the end John's antenna was more in the air than my inverted V.

Inspired by David, VK3IL's build of a matchbox for an end fed half wave which was inspired by PA3HHO's end fed half wave article I reproduced their work today.

Like David, I used 150pF on the input.

Connected to my end fed inverted L it shows decent SWR on 40 and 20m. My transceiver's built-in ATU easily matched on both those bands. Compared to the 40m dipole signals are stronger but so is noise so perhaps the best way to compare is to run WSPR on each for a while.

Like John, I used an FT240-43 toroid and wound 0.8mm wire on it. Cable ties hold the core in place. The plastic box has a snap on base.

Thanks to all who went before. This is a very easy project to build and could be very handy in the field.

Sunday, November 05, 2017

Active on 6m with new J-Pole antenna

My thanks to Peter, VK2EMU, who manufactured a few J-Pole antennas for 6m. A beautiful addition to the shed.

Thanks also to Stephen, VK2BLQ, who kindly gave me a length of water pipe to mount the antenna on.

The antenna is manufactured from square aluminium tube, welded and with a perspex spacer at the top of the J.

I found that mine was a bit short and have added a sliding section of right angle stock to the end to get it to tune up.

The 6m band is quite wide and it's hard to choose where to tune as I'm interested in both 52.525MHz for FM all the way down to 50.293MHz for WSPR and below for digital modes.

The taps for the stub are attached with U-bolts at the moment for easy adjustment. I'm not confident that the connection will be good after a while in the weather but so far seems fine. Peter also supplied some stainless steel long bolts and nuts that I'll switch to in time.

Here's the matching step connected to u-bolts:

I've wrapped the coax ends in self-annealing tape to keep the water out and used some hook and loop wrap to keep a loop of coax in place.

It's resonant at 52.28MHz although the impedance is a little low. My rig can tune it up without any problem.

As soon as I called CQ on 52.525, Ron, VK2GO immediately responded - it's great that there's people around responding to random CQ calls. Thanks Ron.

Sunday, October 22, 2017

Run your own Web SDR with OpenWebRX on Raspberry Pi

There's quite a few excellent remote receivers running WebSDR but unfortunately the author has decided only to give the software to agree to make their server publicly available. I think it's a pity that this software is not available for people wanting to share their home receiver with, perhaps, a few friends. It's also a pity that this software isn't open source.

An alternative is the excellent OpenWebRX by AndrĂ¡s Retzler.

In the ARNSW home brew group we have a regular contact on 80 or 40m but often we can't hear each other due to local noise. It's been proposed that we place a remote receiver at a low noise location and all listen over the web. One idea is to have a fixed receiver simply stream the audio, another is to set up a web SDR. I'm investigating running this on a Raspberry Pi.

The software is available from GitHub here.

There's a few dependencies summarised here:

  • git clone
  • sudo apt install rtl-sdr
  • sudo apt install libfftw3-dev
  • sudo apt install libusb-1.0-0-dev
  • sudo apt install cmake

Everything is in the readme to build and install, I did little except follow the instructions and install missing things as they came up. Let me know if you're stuck.

Because I'm currently running an RTL-SDR in direct sampling mode I had to build a fork of rtl-sdr that supports this.

OpenWebRX is a terrific piece of software, easy to build and run, and I want to thank Andras for his contribution. If you do have a fast internet upload and a permanent receiver you can add yours to the list.


The RTL-SDR doesn't work very well on HF like this so I've now switched to using a HackRF One that's working quite nicely.

The AGC is rather savage but it's good to listen to overall.

QRP by the Harbour - Late 2017

Under threatening skies we had a second "QRP by the Harbour" event in Sydney today.

Facebook worked well to coordinate and publicise the event.

I set up a simple wire dipole fed with just the twin figure eight line and had contacts including local and one into VK4 which was about 800km away.

John, VK2ASU, ran up an end fed antenna high into a tree and had multiple contacts with a Bitx40.

Peter, VK2EMU, set up a magnificent flag pole mast that I think was mostly to mark our location.

Despite good weather at the start it soon turned dark and in the end we faced driving rain and then hail which led us to abandon our position and adjourn to a nearby cafe.

Some lessons were learned for next time:

  • Start earlier in the day - 3pm was late and so many came early
  • Nominate a 2m Simplex frequency for liaison - at least three people turned up but couldn't find us after we'd escaped the waterfront. (I'm very sorry about this).
  • It's tough having multiple stations on the same band, or even harmonically related bands. Maybe we should consider having one main station?

Thursday, October 19, 2017

iPhone to Pixel 2 - what's better, what's worse?

After a few days I'm well in to the new world, for me, of Android Oreo on a Pixel 2. I've kept a list of observations (in Google Keep) of what's better, worse, and what I miss.

What's better

  • Shows incoming call may be spam and lets you confirm or not
  • Launch camera by double tapping the power button (Pixel 2)
  • Ability to not lock when connected to trusted bluetooth devices
  • Front facing stereo speakers on the Pixel 2
  • Great that the Google Home Mini that comes with the Pixel 2 at the moment works as a Chromecast audio device.
  • Works better with Philips Hue lights than going via HomeKit which is a little unreliable for me
  • USB-C. I want this everywhere.

What's worse

  • Don't like some android apps have bumpy animation flashes, even native Google software like play store installs.
  • Front facing speakers on the Pixel 2 aren't so good when I listen to podcasts with the phone in a shirt pocket.
  • Don't like how some apps re-open rotated
  • Facebook chat heads appeared. Happily Apple doesn't allow that.

What I miss

  • Apple watch
  • Airdrop
  • Continuity (copy on computer, paste on phone)
  • Apple Reminders, am using Android Tasks
  • Apple Notes, using Google Keep and chrome extension on macOS
  • Reeder RSS reader, am using TTRSS client
  • Overcasts, using PocketCasts
  • Find my friends, could use Google Maps
  • Fitbit being able to use the step counter in the iPhone, using Google fit but I miss the competition with family
  • Safari not auto-playing videos with sound (coming in Chrome)
  • Spotlight search to launch apps by pulling down on any screen.


  • Deactivate iMessage association with my phone number  (Thanks Jason and Gavin for the tip)
  • I'm looking for a way to import notes into Keep
  • Why do apps in the Google Play store need to be verified with Play protect on device?
  • Android Studio looks nice but HAXM (required to emulate Android O) isn't compatible with macOS 10.13 yet, even in the Beta version.
  • Backup doesn't work. When I decided to switch to the other review phone, the XL, I found that App data, messages etc were all "waiting for backup" on the first phone. This seems to be a known issue that currently doesn't have a fix.
  • I was tricked by a fake Messenger app called "Messenger" with a very similar icon to the Facebook one that showed me full screen ads before bouncing over to the real app. No idea what other terrible things it might have done. I'm not alone.

Tuesday, October 17, 2017

Pixel 2 review from an iPhone tragic

Our family is very much in the Apple eco-system. We iMessage, FaceTime, iPhoto, and watch AppleTV. The family uses Find my Friends and we even have an iCloud cache set up in the house. All said and done, the eco-system mostly “just works”.

But Apple doesn’t meet all our needs and the gaps have always been filled by Google services. We all use gmail and appreciate the huge storage, great search and lack of spam. Photos are backed up to Google Photos and videos are shared on YouTube (I also pay for YouTube Red to avoid those annoying pre-roll and floating ads).

In recent years, Google’s ecosystem has expanded in our world. A Google Home device has become a valued part of our lives in the kitchen, mostly for little things like cooking timers, temperature and weather predictions, some background music and the answers to questions about when a store is open.

Aside from the proprietary Apple iPhone apps, the most used apps are identical on iOS and Android. Facebook, Twitter, Instagram, Tripview, Fitbit and Whatsapp. Transitioning from Apple’s Contacts, Calendar and Photos shouldn’t be too hard...

Physical impressions

The Pixel 2 is a well manufactured device with a feeling of quality about it. It’s just slightly wider and taller than an iPhone 6s but feels lighter in the hand. It turns out to be the same weight as the iPhone at 143g so the lightness is an illusion.

The head and chin are large and the top and bottom speaker slots make it rather hard to pick which way is up - you have to look for the selfie camera or USB-C socket to figure it out.

The screen is super clear although note that it’s set to “Vivid colours” in the settings by default so I wonder about colour accuracy.

The fingerprint reader on the back feels odd at first but I’m getting used to it. When used with a case the reader is rather deeply in a hole which makes it a little hard to poke. There is space for a reader on the “chin” area below the screen so it’s strange that they’ve kept it on the back. Perhaps edge to edge is on the way.

Fingerprint reading is very fast but sometimes fails to read whereas my impression is that the iPhone keeps trying longer. One drawback of the reader being on the back is that you can’t unlock the phone by fingerprint when it’s lying on a desk and must revert to PIN unlock like an animal.

The camera bump on the back is wider than on an iPhone but about the same depth, overall it seems less dramatic because of that width. Given that most people put the phone in a case the bump doesn’t end up being much of an issue.

The review unit came with one of the fabric style cases which is nice and grippy in a top pocket although rather thick.

USB-C is a big win, great to share chargers with laptops, despite some criticism about the varying capability of USB-C sockets and cables it’s a pity Apple won’t be able to move from Lightning cables for fear of a mass uprising for at least a decade.

Apple took the initial heat for dropping the headphone jack but now Google has followed suit. There’s a dongle supplied but the success of today’s wireless headphones show that the era of getting tangled in earphone cables is happily coming to an end.

Migrating from iPhone

In the box there’s a USB-A to USB-C adapter and if you elect to transfer from an iPhone you are instructed to plug your unlocked iPhone in via its lightning cable. When connected, the iPhone believes it’s been connected to a computer presumably running iTunes and asks you to “trust the computer”.

Taking this path of migration ended quickly for me as I have backup encryption enabled on the iPhone so the migration software informed me that only photos, music & videos would be migrated and as I already sync photos to Google this seemed redundant so I skipped it and just logged in with my Google account.

Downloading my apps took about ten minutes followed by 14 updates to pre-installed apps that took another ten or so.

The default screen sleep time was set to 30 seconds, rather fast during initial setup.

What I’ll miss leaving the iPhone for Android

While my email, contacts and photos are already synced to Google, I’m a heavy user of Apple Notes and Messages. Google has Keep for notes and messages is fragmented across Facebook messenger, WhatsApp, Google Allo (they hope), Google Duo, Microsoft Skype and various others. SMS feels like an archaic mode these days but it will do.

Thinking about my iPhone use in recent years, there’s a lot of Google services which have become the daily “go tos”, even Apple recently switched back to Google search from Microsoft Bing and I’m a big fan of Google Photos with its ability to find images by description is second to none.

The main day to day annoyance will be other iPhone users who try to send me an iMessage only to have it mysteriously fail.

Battery life

With only one day with the phone it’s a little hard to tell but so far it looks excellent. I first gave the phone a charge for about 20 minutes then started the install process. During that time it reported battery at 80% with about 13h 17m remaining at current usage (which would be high due to all the updates).

Later, after heavy use, battery was at 65% with 10h 47m remaining.

2h 48m after the charge, it’s at 60%, about 10h 0m remaining, which indicates to me that this phone will have excellent battery life in normal operation.

The GPS seems particularly sensitive and could use 14 satellites quickly on the ground floor of a two story house.


If software is eating the world, then smartphones are eating our gadgets. Car GPSs, music players, games machines and most of all cameras have been taken over by smartphones.

The camera in the Pixel 2 is stunning. It’s helped by the bright high resolution screen but really it’s the machine intelligence that focuses on the right thing, adjusts the light and has portrait enhancing tricks built right in.

Best of all it’s very fast.

Android Oreo

There’s no doubt that Android has come a long way. Oreo is slick with pleasing animations and loads of useful gestures and usage tips as you go. The Google Play store has misleading app titles and the fact that Android scans apps for malware, rather than making me feel safe, makes me a bit nervous.


Speaker audio is not as good as Apple phones which is strange as they have huge slots top and bottom.

The squeeze to trigger Google Assistant seems rather stiff to use, although it’s configurable, and note that you need to squeeze the lower half of the phone - a fact that’s not too clear in the setup animation. I’d like to be able to squeeze to launch the camera instead.

The always-on display of time, notifications and currently playing song is nice but its presence in the battery settings where it’s called “Ambient display” makes it clear that there is a power impact.


Our smartphones are the most used devices in our daily lives and the price should be amortised over the two to three years of heavy use they get. The 64GB Pixel 2 will sell in Australia for $1,079 which is exactly the same price as a 64GB iPhone 8.

The Pixel 2 has more RAM than iPhones but for reasons that aren’t totally clear Android needs more memory than iOS to perform as well.

Despite Google’s stated view that the Pixel 2 is the equal or better than equivalent iPhones it’s clear from Geekbench 4 measurements that they are no match for Apple’s custom A11 CPU.

iPhone 8 single-core: 4252 multi-core: 10201
Pixel 2 single-core: 1914, multi-core 6297
(Higher is better)

Of course, it’s not just about MHz and GB, the machine learning intelligence that Google builds in to both devices and the cloud that backs them makes all the difference in daily use. Being able to search your photos for “betty hugging a dog” is not affected by CPU speed but rather by cloud smarts.

If you live in the Google ecosystem then this is a terrific phone and, coming direct from Google, is sure to get security and software updates faster than third party Android hardware makers. If you’re an Apple tragic then you might be best to stay put.

Pixel 2, and the larger Pixel 2 XL model, will be available in Australia late in October.

Saturday, October 07, 2017

Tesla Tiny House - disappointing

Tiny houses are fascinating examples of efficient, frugal, tidy living and I was excited that the Tesla Tiny House was coming to Lane Cove near me this weekend.

This was not what I expected. Rather than a house, it is a box, with a battery, some panels on the roof and a salesman inside. Disappointing.

Tuesday, September 19, 2017

Very simple 40m portable dipole with speaker wire.

Talking with Ross, VK1UN, the other day we stumbled on the simple idea of using figure 8 speaker wire as the feed line up to an "inverted V" dipole held up with a squid pole. Compared to feeding with coax up to a balun, this is extremely light weight and so doesn't bend the squid pole too much.

The video above takes you through how it works.

This is the antenna a plan to take to the next Sydney QRP by the harbour event coming up in October.

Handy lightning map

Brian, VK2AAF, just alerted me to a fantastic map of current lightning. LightningMaps.

Were were talking on 80m and there was quite a lot of noise but the weather here is fine. Turns out there's a lot of lighting off the coast towards New Zealand.

Very handy, thanks Brian.

Wednesday, September 13, 2017

Simple Fronius logger

If you can install python (which you can pretty much anywhere) here's a little script to get started with logging from Fronius inverter.

The latest source code is here.
import requests
import json
import datetime
import time

# Set this to the IP address of your inverter
host = ""
# number of seconds between samples, set to zero to run once and exit
sample_seconds = 60 * 5

def main():
    while True:
            watts = watts_generated()
            now = time.strftime("%H:%M:%S")
            line = "%s\t%s\n" % (now, watts)
            # print(line)
        except requests.exceptions.ConnectTimeout:
            print("Connect timeout at %s" % time.strftime("%H:%M:%S"))
        if sample_seconds > 0:

def write_to_logfile(line):
    today = time.strftime("%Y_%m_%d")
    file_name = today + ".csv"
    out_file = open(file_name, "a")

def watts_generated():
    url = "http://" + host + "/solar_api/v1/GetInverterRealtimeData.cgi?Scope=System"
    r = requests.get(url, timeout=2)
    json_data = r.json()
    result = json_data["Body"]["Data"]["PAC"]["Values"]["1"]
    return result

if __name__ == "__main__":

Note that I'm assuming Python 3 and you'll probably need to install the requests module. The program outputs a single file for each day.

Here's some code to draw a pretty graph.
Simple code to draw a graph of a day of power.
Requires matplotlib

On Fedora Linux: sudo dnf install python3-matplotlib


import matplotlib
import matplotlib.pyplot as plt
import matplotlib.dates as mdates
import csv
import time
import datetime

today = time.strftime("%Y_%m_%d")

INFILENAME = today + '.csv'

def main():
    data_reader = csv.reader(open(INFILENAME,'r'), delimiter='\t')
    y = []
    x = []
    for row in data_reader:
        if len(row) > 1:
            timeval = row[0]

            dt = datetime.datetime.strptime(timeval, "%H:%M:%S")
            print("timeval = %s -> %s" % (timeval, dt))
            watts = float(row[1])

    fig, ax = plt.subplots()
    my_fmt = mdates.DateFormatter('%H:%M')
    plt.savefig('%s_graph' % today)

if __name__ == "__main__":

Finding the IP address of your inverter is pretty easy if you have a network scanner such as nmap. I use LanScan on macOS and the Fronius comes up as having a network interface from "u-blox AG".

Saturday, September 09, 2017

Solar electric panels installed at home

The ham shed has been solar powered for many years. Finally it was time to install PV panels on the roof of the house.

The panels are installed on the west side of the roof as we already have solar hot water on the north side. Afternoon power might work well for running the air-conditioning on hot days.

Our last quarterly electricity bill was $447 and they say our average daily usage is 14.54kWh. (Yesterday the system produced 16.2kWh for the day, but much of it was excess).

We've put in 12 275W REC TwinPeak panels to give a theoretical total of 3.3kW. The house is three phase so we've gone with a Fronius three phase 3kW inverter.

The inverter sits next to the electrical switch box and there's a "smart" meter inside the box through which power to the house runs so it knows how much we're generating and how much we're using locally.

The Fronius connects to the home Wifi and pushes data up to a web site. For free it keeps three days of data and if you pay it keeps it longer. Here's how a full day without clouds looks:

The big lump of usage in the evening was me baking dinner. This is where a battery would obviously help.

Here's the highest power generation I've noticed so far:

I paid AU$6,201 for the system and given that we pay about $1,600 per year for electricity now, I'm hoping that it might pay for itself after about 5 years but this remains to be seen.

We currently pay about 24c per kWh but the feed in tariff is just 6c but on current figures there's quite a lot of spare power available to earn credits. After the next bill I intend to take the Prime Minister's advice and shop around to get a better price and better feed in tariff.

Already I've changed my behaviour in that I wait until sun falls on the panels from 9am before turning on the clothes and dish washing machines to take advantage of solar power. For breakfast I make coffee in a gas stovetop device.

A battery is an obvious enhancement but I'm not convinced that it would pay for itself any faster given the extra investment.

The German made Fronius inverter is an interesting device. As well as pushing data to their web site (or you can configure it to push to your own url) it has a group of web service APIs that produce JSON data. I have a simple project in mind to build a display of key data for the kitchen.

I think providing well documented open APIs in smart home devices is a key feature and I certainly chose to pay a little more to be connected. They have smart phone apps but oddly they have less information than the web site.

With a little hacking here's a little power generation display built with an ESP8266 and an OLED display.

HF radio interference?

I was concerned about this and chose not to go with panels that have built-in inverters. My tests so far show that the system does not produce noticeable HF interference when in operation. I have held a radio up to the inverter tuned off stations and can hear very little effect. Potentially having big diode panels on the roof might rectify HF transmissions but so far I haven't noticed any effects.

Monday, September 04, 2017

Door bench for the shed

A very simple, cheap, upgrade to my shed today. I've always struggled to build things on little folding tables. Today I paid AU$29 for a door and it makes a fine bench.

It's a hollow door so won't take much weight in the centre. I'm thinking of putting some sort of edge on it to stop things rolling off. I'll keep this next picture as a reminder of what it looked like originally.

The door is a narrow model. It's 2040x720x35mm. (I have no idea how many furlongs that is for you Americans).

Friday, August 18, 2017

Building wsjt-x 1.8rc1 on Fedora 26

The available binaries of wsjt-x don't run on Fedora 26. There's no problem building but it took a while to figure out the dependencies so this post is a note for myself that might help someone else.

From a fresh Fedora 26, here's the dependencies I needed to add before building.

sudo dnf install autoconf automake libtool libusb libusb-devel fftw-libs-single fftw-devel texinfo qt5 cmake asciidoc gcc-gfortran gcc-c++ qwt5-qt4 qwt qwt-qt5-devel qwt-qt5 qt5-qtmultimedia qt5-qtmultimedia-devel asciidoctor qt5-qtserialport qt5-qtserialport-devel

I stumbled around a bit figuring out what the missing thing was called in Fedora so there's undoubtedly things in that list that aren't actually needed.

At the end of the build I got an error linking -ludev so needed to do this to let ld find the library.

sudo ln -s /usr/lib64/ /usr/lib64/

(Let me know if there's a correct way to do this, I couldn't find a -devel package that should normally do this).

I basically follow the instructions directly from the excellent INSTALL document but I'm substituting the 1.8rc1 tag so I get the latest FT8 stuff.

cd ~
mkdir wsjtx-prefix
cd wsjtx-prefix

Download a snapshot from:

Unzip then rename:
mv wsjt-wsjt-8028-tags-wsjtx-1.8.0-rc1 src

From the file src/INSTALL, follow the instructions to download, build and install hamlib.

# As per the instructions in INSTALL
cd ~/wsjtx-prefix
mkdir build
cd build
cmake -D CMAKE_PREFIX_PATH=~/hamlib-prefix ../src
cmake --build .
sudo cmake --build . --target install


Building is a good way to exercise your CPU.


I notice this site hopes to have binaries available but the builds seem to be failing. Does anyone know what I need to do to build wsjt-x as a static binary for easy distribution?

Sunday, August 13, 2017

Charging a laptop from 12V

Keen on portable QRP operation, I'd like to use digital modes which might require a laptop. While battery life is excellent with some models, I'd also like to be able to charge a laptop from my solar powered shed.

Recently I purchased some voltage buck modules which can step up a voltage to a settable output controlled with a multi-turn potentiometer.

There's lots of variations of these on ebay. This one takes an input of 3-35V DC and turns it in to an output of 2.2-30V DC with an output current of up to 1.5A.

I'm charging a little HP laptop which takes 19.5V so the converter is set to that and all boxed up nicely. (Except that I drilled the holes in the wrong places).

HP laptop chargers have three wires in the lead, positive, earth and ID. The ID wire (I learned thanks to commenter Brian G8OSN) needs to be pulled high for the laptop to charge the battery. I connected the middle ID wire to positive 19.5V via a 100K resister and that seems to do the trick.

On a related topic, I'm becoming a fan of 18650 Lithium Iron batteries, not just for super bright torches and Tecsun radios, but also for powering QRP gear if powered from a set of three 3.7V cells in a little case available for under $2.

These cells can be harvested from old laptop battery packs. Often when they die it's because one cell has gone bad and the others can be re-used. They don't make it easy to get them out though.

This pack from an old Asus netbook has three rows of two cells in parallel. These cells have a huge capacity compared to an AA rechargeable which might be 1,200mAHr, they are often 5,000mAHr or more. Here they are in the fancy new charger that's just arrived.

I see that this month's Silicon Chip has an article about these cells.

Monday, July 31, 2017

Meetup with Peter VK3YE

Peter, VK3YE, was in Sydney briefly and a few of us had the pleasure of meeting up before he braved the enhanced airport security. Stephen, VK2BLQ, brought along his beautiful valve regenerative radio.

John, VK2ASU, made the journey from Maitland and brought a few interesting projects for inspection including a Tuna Tin radio.

After Peter left we had a duel between John's regenerative 80 receiver and a Tecsun PL-880.

Thanks Peter for popping by. Catch you on the air by the bay or the harbour!

After lunch, John and I walked around Chatswood inspecting cameras, telescopes, 3d printers and torches. After becoming familiar with the prices out of China on Banggood and AliExpress it's hard to take the retail prices of many of these products.