On Saturday, April 23, I attended a rally by ABC Friends Victoria at which Shadow Attorney General, Mark Dreyfus spoke. I've long been a supporter of shortwave broadcasting from Australia both for the inland but also the Pacific and was disappointed when it was shut down. It was a bit of a surprise when Mark Dreyfus mentioned shortwave in part of his speech.
No policy announcements but interesting that he mentioned shortwave.
Once again it was my pleasure to be a guest on the ABC RN program "Download This Show". You can hear it here.
Marc Fennell is away making a TV show so the fabulous Rae Johnston was guest host. The other panelist was Manal al-Sharif who makes the Tech4Evil podcast.
This episode was recorded remotely. I'm at my rural antenna farm connected via NBN fixed wireless and it all worked rather well.
I upgraded a machine to Ubuntu 22.04 and found that wsjt-x couldn't see the serial port any more.
lsusb shows the device:
Bus 001 Device 005: ID 10c4:ea60 Silicon Labs CP210x UART Bridge
It seems that Ubuntu has added a bunch of Braille devices, one of which conflicts with the serial device in the Icom radio.
The trick is to edit the file:
sudo nano /usr/lib/udev/rules.d/85-brltty.rules
and search for "10c4:ea60"
Then comment out the line starting with ENV{PRODUCT}:
# Device: 10C4:EA60
# Generic Identifier
# Vendor: Cygnal Integrated Products, Inc.
# Product: CP210x UART Bridge / myAVR mySmartUSB light
# BrailleMemo [Pocket]
# Seika [Braille Display]
#ENV{PRODUCT}=="10c4/ea60/*", ATTRS{manufacturer}=="Silicon Labs", ENV{BRLTTY_B>
The Icom IC-705 has network features that IC-7300 owners can only dream about. Happily for us macOS users, there are two software programs that do a good job of remote controlling the radio.
The first is a commercial program SDR Control by the guy that does the iOS software for Flex Radio SDRs. It looks like this in operation:
The window can be made smaller (but not as small as I'd like) for casual listening while doing other stuff on the computer. Here's a bit of the VK2WI broadcast monitored here on 30m. The station is about 800km from me and comes in very well.
A new version, for iPadOS has just been released. It's not cheap but works well. As a software developer I can imagine the work that has gone in to this app.
The other option is free and open source. WFView (Waterfall View) is available for Linux, Windows and here I use it on macOS:
Both work well. SDR Control has additional features including built-in digital mode clients but WFView works perfectly well.
I hope that one day Icom releases an update to the IC-7300 with network capabilities like the IC-705.
WFView can connect to the USB port on the IC-7300 and make it available on the network but it ties up a computer. WFView source code is here.
Home brew master, Stephen, VK2BLQ has been at it again and has created a two valve regen a la 1967 All Wave Two, using two 6BL8 or 6U8 triode pentodes (heaters in series), and it still works with a 12 V HT supply instead of the 90 V used previously:
Stephen writes:
"The receiver sort of works, but the 12 V supply limits the audio output, so is only good for headphones or feeding to an external amplifier. The stability on 40 m is Ok but overloads on strong signals, so I think an antenna pot might be better than the volume control, doing double duty, but it does combine the glamour of thermotron technology with the safety of low voltage.
For the makeshift vernier dial I used an old audio CD , which as fortune would permit, possesses the magic of Soldersmoke so is destined for greatness. Hacking an old variable pot and two grommets seems to function as a vernier drive.
Audio quality on the 39 m AM shortwave band seems to me more pleasant than one of the superhets and 40 m SSB and CW sounds "mellow". (Click to enlarge image).
I did make some circuit changes to suit the lower voltage: I changed the pot and resistors for the Regen control and I did use a 230v to 6v mains transformer for the speaker. Valves are great, the 6U8 worked with the same components even though I didn't have a 6GW8.
Next version gets the upgrades and a heterodyne converter, and if I can quote a line from the TV series "The Nevers":
"It's a prototype".
If anyone actually has questions, I'm happy to help."
Here it is in action:
-- It's a fine looking prototype if you ask me. Thanks Bill for the link from Soldersmoke!
This week I had visits from several hams including Dave, VK3ASE, who brought a long squid pole and an offer to help with antenna raising. Dallas, VK3EB, helped with the off centre fed dipole.
I decided to try raising a line over a nice clear tree branch with a drone rather than the squid pole. The drone could lift the line without problem, the issue (which I anticipated), was landing again on the other side with the line now trailing above the drone.
Despite my best efforts to keep the line between the rotors eventually it tangled and the drone struggled for a while before I shut it off. This left the drone hanging from the line but undamaged. Dave recorded some video of the enterprise:
The supports for the ends of the dipole were in trees with substantial leaf cover so we used the squid pole for those.
My antenna tree supports an Off Centre Fed Dipole cut for 80m that does very well on 40 and 20m. Now it has a second support that currently has a dipole cut for 30m. The branch is nice and clear so the drone was easy to fly over it.
The Bendigo Amateur Radio Club held a meeting where Brad Geier, VK3VLK, spoke about the great future of Digital Radio Mondiale (DRM) transmission. I didn't realise that the ABC has been running a transmitter on 747kHz from Wangaratta.
I can see the transmission quite clearly here at Drummond and also on the PkLoops SDR at Croydon.
In the past I've been able to receive DRM transmissions from Radio New Zealand International and they can sound very similar to FM quality despite weak signals and band noise.
The software needed to decode DRM is Dream. I couldn't get the latest version, 2.2 working but version 2.1.1 does work under windows. Another interesting lead is swradio-8 which I was able to build but not quite get going on Linux.
I'm using the IC-7300 as receiver by switching USB audio output to IF, choosing AM and winding the bandwidth out as much as possible.
My antenna is not very well suited to 747kHz so I'm not decoding audio just yet:
In the old (pre-COVID) days we used to go to ABC studios but these days we're well practiced in recording from home. Even Marc was at his home.
My internet here at Drummond is NBN fixed wireless and unfortunately upload speed isn't reliable enough for my taste so I travelled to Melbourne for the recording.
If you're interested you can get more info and listen here.
The supply is quite low noise, but there are lines visible on the waterfall about every 2kHz if I turn the preamp on.
Unlike switching supplies I've used with HF receivers in the past, where there are broad bands of noise that drift up and down, in this case they are narrow and the "noise offset" control lets me move them away from the frequency I'm listening to.
The supply is very compact and has a fan that doesn't seem to run, presumably it does when it gets hot.
My iOS app, WSPR Watch, displays WSPR spots pulled from WSPRnet.org and features a very simple transmit capability. People often ask if I could make it receive WSPR as well.
The obvious approach would be to port the decoding code from wsjtx but that source base is pretty daunting and includes several languages including Fortran.
I went looking for other implementations and stumbled across rtmrtmrtmrtm's weakmon which is an almost pure python implementation (there's a few bits of c). The project hasn't been updated for some time and I ran in to a few issues running under python 3 on Ubuntu linux.
Weakmon directly reads audio from an input (including things like the IC-7300 I'm using) and can use serial CAT control to hop bands so it's very functional.
I found the most recent fork by kholia and forked that to create my version here.
My focus is on WSPR and running under python3. Other modes may not be working.
My low noise reception seems worth sharing with a few friends so I set up OpenWebRX. I initially tried on an Ubuntu 21.10 laptop but for some reason couldn't get the AirSpy HF+ to work with it even though SoapySDR said all was well.
In the end I gave up and tried the easy option with was a pre-made image for Raspberry Pi. This worked well right out of the box.
This is a very low noise location but do you see that big band of interference down the left side? It seems to be from the Raspberry Pi or it's USB power supply. Very distressing. The lowest noise USB power supply I have is a battery pack with USB output. I've ordered a metal case for the Pi and some clip on ferrite chokes for cables and will be interested to see if things can be improved.
Despite my reservations, the 31m shortwave broadcast band comes alive in the evening here:
I first set this up on a Pi 3B which worked but struggled a bit. The Pi 4 is a very capable computer and handles the load with ease even with some background decoding of WSPR and FT8.
Great work by the OpenWebRX developers!
It's been great having a dipole up high in the trees but I wanted to be able to use more bands so I made an off centre fed dipole, cut for 80, fed with a 4:1 balun. This gives me a number of bands with a low enough reactance that the IC-7300's tuner can match it. Here's a plot using AntScope2 on macOS.
The grey bars are ham bands. I'm sweeping from 3MHz to 30Mhz. As you can see I get low SWR on 80m, 40m, 20m, and 11m. With a manual tuner I've been able to use 30m but it's quite a stretch.
Speaking of stretch... The antenna wire is half of a figure-8 speaker wire and I think it is slowly stretching. I had a doublet for 160m up but the wire broke.
I did notice that 40m on the OCFD was not as good as it was on the dipole cut for 40m but the extra bands and convenience make it worth while.
The shack is improving! I ordered a 2m bench, a gas chair, and a 4 draw unit from Ikea. Delivery cost almost as much as the furniture.
The afternoon sun hits the other side of the corrugated iron in front and it gets very hot. Next step is to insulate and line that wall at least.
Update: Winning at WSPR reception
It's a combination of height, antenna and of course the low noise location. I'm pleased to see that after 24 hours of WSPR reception on 40m I'm at the top of the global chart by accumulated distance.
The WSPR challenge is a wonderful idea. I love the concept of competing by reception rather than transmission.
(Of course it's a bit unfair as we VKs are very distant from most stations so we have an advantage).
At my new location I was able to throw a line up a tree to support the balun for a 40m dipole. Dallas, VK3EB, kindly visited with an 18m squid pole and was able to get a line over a much higher branch.
With extra height, reception, as measured with WSPR, is visibly improved.
Sincere thanks to Dallas for visiting and helping to improve the antenna.
I've continued to work on the 40m dipole here at Drummond and, despite an arm in a sling, managed to throw a line with a rock attached over the branch of a tree and hoist the balun up about 6m above ground. I've also got the dipole to be resonant within the band for a change.
All was going well until a very regular interference pattern appeared across the band. It didn't look like a switch mode power supply as the carriers are quite narrow and didn't drift. Very annoying as some were dead on popular frequencies like 7100kHz.
My first theory was that it was from the micro-inverters in the solar system here. They have a bad reputation and the sun was strong. I isolated the inverters and it stayed. In the end it turned out to be a switching wall power supply for a Synology NAS that I had recently installed. Now the band looks clear:
At 6:30pm local time I had a contact with stations VK2ASU at Maitland and VK2KB at Emu Plains. I could hear them both perfectly but due to the short distance they struggled to hear each other. Here's a video of just tuning around 40m. Hugely different to the experience in the city.
I normally look for good times to talk with John, VK2ASU by watching my WSPR reception of his club station VK2ATZ. Here's a signal to noise plot from the WSPR Watch App. Times are local. (There's a gap when we had our voice contact).
So, very happy with 40m operation now, the next step is more bands and general coverage reception.
I've moved my shack into a shed and strung up a better dipole in some trees but away from everything electrical. Signal reception is improved and I heard Mark, VK3MJ, calling CQ and had my first voice contact from Drummond. The band looks great with very little noise at the moment.
The hum you can hear is a linear power supply sitting on the bench which unfortunately hums loudly. I'm not sure what to do about that.
I left WSPR receiving on 40m over night and got very good results, (not quite up to VK7JJ's fantastic reception performance though).
I even received Ross, EX0AA, from Kyrgyzstan, many times at up to -13dB SNR. These screen shots are from the WSPR Watch app.
With my new low noise QTH I'm able to hear Alan, VK2ZIW's FreeDV 700e beacon on 7177kHz.
He's running 20W from Emu Heights in NSW. The beacon transmits every 10 minutes.
Normally I use Linux but the version of FreeDV in the Debian library is too old for 700e so I used the macOS version.
At Alan's prompting, I grabbed the freeDV GUI software and built it on Ubuntu 21.10 with no problem. There's a build_linux shell script that does all the hard work.
Alan's beacon has a feature where if you put your callsign in the text message it will replay your transmission back to you.
Unfortunately the macOS build seems to have a bug where the message field isn't editable. UPDATE: I found the message field in the "options" dialog. My mistake.
I'm looking forward to some FreeDV contacts in the future!
It's long been a dream of mine to have a location for HF reception in a quiet place outside of the city. Since we moved to Thornbury about two years ago I've been plagued with high levels of broadband noise which has left the HF spectrum, particularly on 40m, at often S9 +20 DB.
That's the worst example. Amazingly even through high-level noise like this digital modes such as WSPR can still receive a few signals and I'm able to copy Steven VK2BLQ sometimes.
The dream of a second location has finally come true with the purchase of 5 acres north of Melbourne at a place called Drummond.
40m looks completely different here:
Between signals it's S0 most of the time.
To measure the difference in signal-to-noise, Stephen transmitted five watts of WSPR from Sydney and I received simultaneously in both locations. The difference is huge. The largest difference I saw was 21dB better signal-to-noise at the country location!
Here is WSPR reception of stations more than 400km away:
For the initial setup, the antenna is far from optimum, it's just a wire dipole hanging up right next to the house with some coax going in through the kitchen window. This can be greatly improved in the future.
How much better is HF reception outside of the city I measured at up to 21dB.
PS: Unfortunately it's going to take me a while to improve antennas as during the initial move in I missed a step and fell heavily, breaking my left arm. This post has been written using the Apple built-in dictation system which I find to be excellent.
We're not a big country really. It seems odd that each state has evolved a daily COVID report that broadly looks similar but has the various statistics in different orders.
I favour the South Australian approach which focusses on hospital patients and deaths.
