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.

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.

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.

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 András 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 https://github.com/simonyiszk/csdr.git
• 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.

Update

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?

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.

Notes

• 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.

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.

Camera

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.

Observations

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.

Conclusion

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.

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.

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.

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 = "192.168.0.112"
# number of seconds between samples, set to zero to run once and exit
sample_seconds = 60 * 5


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


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


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__":
    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
matplotlib.use('Agg')
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))
            x.append(mdates.date2num(dt))
            watts = float(row[1])
            y.append(watts)

    fig, ax = plt.subplots()
    ax.plot(x,y)
    ax.xaxis_date()
    my_fmt = mdates.DateFormatter('%H:%M')
    ax.xaxis.set_major_formatter(my_fmt)
    plt.ylabel("Watts")
    plt.xlabel("Time")
    plt.show()
    plt.savefig('%s_graph' % today)


if __name__ == "__main__":
    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".

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.

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).

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/libudev.so.1 /usr/lib64/libudev.so

(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:

https://sourceforge.net/p/wsjt/wsjt/HEAD/tree/tags/wsjtx-1.8.0-rc1/

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

wsjtx 

Building is a good way to exercise your CPU.

Binaries?

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?

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.

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.

Lubuntu Linux for low power, low memory computers

I like the little HP Stream 11 laptop but Ubuntu is a bit slow on it so I've recently installed Lubuntu Linux. Based on Ubuntu but with a lighter weight desktop and windowing environment it runs well and does not use the 2GB of RAM available in this machine.

Even with the Chromium browser running there is free memory available.

To find out more detail about where your battery power is going, there's a utility that can be installed with apt, called powertop.

Amazing to see an Intel laptop consuming 3.55W.

There are a bunch of tunable settings that can be adjusted in Linux to get better battery life, mainly turning on some power management settings, I've turned on each of these and so far so good.

While Lubuntu is fine, I do miss a few things from full Ubuntu such as the ability to search for an app to run it, also the window edges are very narrow and rather hard to grab with the mouse.

I've noticed that some operations, such as 'apt update' hang for 120 seconds before starting. At first I thought this was a DNS issue but it turns out that disabling ipv6 fixes this for me. (Obviously, I would prefer to use ipv6 but perhaps my ISP or home network isn't quite up to it).

All in all, worth a try on a low end laptop.

Tecsun PL-880 mini review

There was a time when Sony ruled my portable short wave listening world. In recent years Tecsun has brought out a series of decent radios suitable for packing on trips.

This week I popped in to Av-Comm nearby in Brookvale, local distributor of Tecsun and purchased a PL-880 from them. (They're not really set up for walk-in customers but very friendly none the less).

The PL-880 is powered by a single high capacity Lithium 18650 battery which is charged inside the radio using a mini-USB socket on the side. Av-Comm supplies a suitable cable and plug pack but it's likely you already have one lying around.

These 18650 cells are turning up everywhere these days, in high brightness torches, even in home made power walls, and they seem like a worthy successor to the ubiquitous AA cells. Being 3.7V they can power lots of devices with just one cell.

The radio comes in a very nice faux leather zip around case that includes a log book. There's a large world map poster with ham radio prefixes marked on the countries and Av-Comm includes a guide to short wave listening.

Audio is excellent, probably the best I've heard in a portable radio. AM and FM sound terrific. There is a "bass" or "treble" switch that I've left in treble position but there's still a warm sound there.

On shortwave, sensitivity seems excellent. Here's a bit of Radio New Zealand International using just the whip antenna inside the house.

During this video I switch the DSP bandwidth a few times but I think this is a pretty narrow transmission.

The radio also has proper upper and lower sideband. Here's a recording of a 40m LSB conversation again just using the whip antenna.

You can hear that the tuning, although digital, is silky smooth. This is where this radio shines, previous models from Tecsun and others have not tuned well - making a chop chop sound - but this radio slides smoothly and the separate course and fine tuning knobs work well particularly if you're interested in sideband.

There's a switch for the display light that if you turn it on keeps the display lit even when the radio is turned off. Normal mode is to light up when you touch a control and then turn off again after a few seconds.

I found that the radio shows some signs of being overloaded when on the most sensitive position, various spurious signals can be heard that go away with the attenuator switched to the first position.

In all a great radio with controls familiar to you if you've ever had a previous Tecsun radio. My favourite feature is the sleep timer that turns it off after a settable period of time at night. High sensitivity, lovely smooth tuning, passable sideband and big clean sound that can fill the room. Recommended. AU$249.

Amazon Lightsail doesn't have virtual memory

My cloud hosting needs are modest. A couple of Wordpress blogs, an OpenVPN server, and a Tiny tiny RSS server. I use Amazon’s AWS services for S3 storage for miscellaneous files and backups using ARQ. When Amazon launched Lightsail with a VPS starting at just $5 a month (for 512MB RAM and 20GB SSD), I moved over from Linode where I was paying double that.

All seemed good at first, Amazon’s infrastructure gave me better ping times than others, but I noticed that mysql was going away from time to time. Tailing the system log I could see kernel out of memory messages and that it was killing mysqld. You see entries saying "OOM". The kernel kills the process that's using the most memory which tends to be mysqld.

My first thought was to increase the RAM but there’s no simple way to do this on Lightsail, you must take a snapshot (backup), make a new instance with the new memory and build it from the snapshot. When all is up the external static address is simply re-pointed to the new instance and the old instance can be stopped. This isn’t at all difficult but it seems like something computer software should do.

After upgrading the RAM it dawned on me why Linux was running out of RAM - Lightsail instances have no virtual memory! It turns out there’s no easy way to add a swap partition and they actually warn that if you did it would be too slow.

Paying $10 a month for a Lightsail instance with zero virtual memory becomes uncompetitive with my old favourite Linode who offer 1GB RAM and 30GB SSD including VM for the same price.

So, I’m back on Linode and frankly happy to be there. Amazon is a gorilla in the hosting game but their offering is incredibly complex and, it turns out, has some little gaps.

I realise my home use is at the very low end but, as the song says, “from little things, big things grow”.

Not having any virtual memory is a major problem for any real server.

Update: another low cost VPS provider: Vultr

Vultr is a new provider of virtual machines that starts (at the time of writing) at US$2.50 per month for 1CPU, 512MB memory, 20GB SSD and 500GB of bandwidth.

A suggestion from John.

Bandwidth is charged at the maximum of incoming and outgoing. Excess bandwidth is charged at 1 to 5 cents per GB (depending on where). You continue to be charged for a stopped instance - you must "destroy" it to stop being billed.

OS options are CentOS, CoreOS, Debian, Fedora, FreeBSD, OpenBSD, Ubuntu, Windows or upload your own.

They claim to be faster than competition from AWS and Rackspace and given that I'm in Sydney and they have a location here, I'm going to give them a shot.

Accounts must be topped up before use, so I guess this is pre-pay, but once a first payment has been made they take Bitcoin which is handy.

Hmm, bait and switch eh? It turns out that once you pay them some money, the US$2.50 server size is "sold out" in Sydney... not impressed. By default the Ubuntu image has no swap, like Lightsail, but they have a guide to manually adding a swap file.

New weak signal mode FT8

Although it sounds disturbingly like a new rig from Yaesu, FT8 is actually a weak signal QSO mode from K1JT, Joe Taylor, and the folks who gave us WSPR and other modes. The mode is Franke-Taylor design, 8-FSK modulation.

I've just had my first contact with Steve VK6IR who is located right across this wide brown land.

I saw his CQ, received at -4dB, double clicked the line and the rest of the QSO, including signal reports each way, was automated.

Unlike WSPR where each over takes two minutes, the cycle time in FT8 is just 15 seconds so it feels a lot more like you're actually having some sort of conversation.

This new mode is in the latest builds of WSJT-X, version 1.8.0-rc1 in my case.

The release notes describe FT8 as follows:

"New mode called FT8: sensitivity down to -20 dB on the AWGN channel; QSOs 4 times faster than JT65 or JT9; auto-sequencing includes an option to respond automatically to first decoded reply to your CQ."

AWGN is Additive white Gaussian noise, obviously.

I kind of wish this was all a little bit more manual and that I could have a few more characters to personalise the QSO. Maybe we need a Twitter like digital mode?

Participating in GovHack

It's GovHack time again! This year it will be held over the weekend from Friday 28th to Sunday 30th July 2017. Back in 2015 I joined a team called "Hackasaurus Rex" with daughter Cat and her boss Ben and we participated at the Canberra location.

Ben brought graphic design skills, Cat did data analysis and transformation (in python) and I did iOS development.

On Friday night we looked at the amazing array of data available and came up with the idea of making an app that lets you check a place to live to see how... "liveable" it is.

The effort involved grabbing data from a variety of sources, normalising that data into scores that indicated the "goodness" of a location. Some data sets used postcodes and others used suburb names so there was some work required to map these.

While it was freezing cold in Canberra, the atmosphere in the room was warm and focussed.

I think having a small team worked well for us and the fact that our skills were all different and yet complementary meant there wasn't much overlap. Our entry suited the iterative development style that a hackathon invites in that we had something working pretty early on Saturday and were then able to add more data until we figured it was time to write up what we'd done and make the video you need to enter:

Making the video does take time and our approach was to make a recording of the mobile device screen first and then record a description which was added as the audio track later. Some teams did things as simple as making a slide show and exporting it as a movie while others made full on documentaries about their entry.

GovHack is a wonderful event, it encourages diverse teams to come together to work with fantastic data from enlightened government departments. The sponsors that get behind it are to be applauded and the organisers do a great job. This year I'm a volunteer and will be hanging out at the Sydney event.

If you're reading this before 28th July, get over to govhack.org to find out more and register. I look forward to seeing you there!