Sunday, May 15, 2022

Built the QRPGuys AFP-FSK Digital Transceiver III kit

A QRP Labs QDX digital transceiver kit is on order but in the mean time I was looking for information on the technique Hans uses to modulate the Si5351 from a computer generating FSK modes, such as WSPR. The manual mentions that the way it works is to measure the frequency of the audio coming in from the computer and then directly set the Si5351 frequency. This means there's no mixing and no opposite sideband. Very clever!

It turns out that this idea is not new and dates back many years, even implemented on a Z80.

While QRP Labs keeps much of their source code secret, another vendor - QRP Guys - have a transceiver that uses the same system and they supply the source code.

I have just finished building and debugging their Digital FSK Transceiver. It's not as neat as the QDX as it uses analog audio in and out. Transmission is by VOX so it's not a huge problem.

The kit went together well but I couldn't get it working even though the display showed the right things. It didn't auto-detect the low pass filter band (there's a resister divider to signal the band by voltage).

I downloaded the source code and wrote to QRP Guys to tell them they linked to the wrong source. I was wrong of course and failed to read the file called README First which explained that the same source file is used for a few different projects.

Ken LoCasale replied with LOL after I realised my error. Nice quick response from the QRP Guys.

Unable to get the kit working, I built the code and flashed an Atmel ATmega328p chip in an Arduino Uno. When I swapped that chip into the VFO board the receiver sprang to life.

As you can hear, SSB reception is good but the 1kHz tuning step is a little large for SSB reception. I haven't calibrated my oscillator so that might help.

Driven with audio from WSJT-X I saw 38V peak to peak into a 50 ohm dummy load running on 13V.

After calibration I had an FT8 contact without any problems.

20m is very active today. For such a simple receiver (Si5351 + NE602), it does a great job:

It's great that QRP Guys have shared their code.

Interestingly the code that made version 3 of this project possible was shared by Kazu Terasaki AG6NS. There's a discussion here. His GitHub page has several projects and there's a branch with the official QRPGuys version.

I'm very much looking forward to the QDX which has a single USB interface to the computer and an apparently very good SDR receiver. This is a good kit and fun to tinker with.

Wednesday, May 11, 2022

Wifi router, Gl-inet GL-AX1800 makes measurable improvement to speed

My internet here at Drummond isn't great. It's NBN Fixed wireless. While the download speed is OK I experience packet loss and have trouble with video calls some times.

Recently I've noticed that the Apple TV would sometimes have very low download speed such that streaming video dropped back to a very low bitrate version. I have been using Google Wifi mesh devices but was frustrated by the very limited control available through the Google Home app.

I decided to buy some Wifi routers that run OpenWrt, I chose the GL•iNet AX1800s. AKA Flint.

If the client is capable, these routers can provide gigabit speed over wifi. Of course, my internet connection is way below this. Having replaced the Telstra Wifi router with one of these I find that the broadband speed, as measured with the Ookla app is about 10Mbps faster than previously.

Note the terrible 12% loss though (not in my network). Interestingly ping loss is zero but I see loss during speed tests so I guess it's larger packets that are dropped.

Here we have two buildings and they are linked with ethernet so a second router is used in the shed to extend the network by setting it to "Access Point" mode.

The meaning of this setting was not obvious to me and googling how to do this on OpenWRT led me down a complex and incorrect path before I reset the router and looked more deeply.

Access Point mode means that the router shares the network available on its WAN port via ethernet and Wifi without doing its own DHCP or NAT.

Wednesday, May 04, 2022

Insulated shack with antenna pass-through

Here at my low-noise country lair the storage shed I use for my ham radio shack was going to get very cold now that winter is coming.

I've had a carpenter insulate and line the space and a challenge was figuring out how to connect radios to antennas. 

Ross, EX0AA, suggested SO-239 bulkhead adapters:

I asked the carpenter to create a lined port to the outside and I've mounted a plate on the inside wall like this:

On the outside I've mounted a hinged plate to keep rain out of the cavity.

Underneath coax can connect.

The gaps around the port were filled with expanding foam filler.

With some, rather off level, shelves; the shack is now working well.

The concrete floor needs a bit of carpet.

Last night I joined the Macedon Ranges Amateur Radio club 80m net. It was 10C outside but, with the help of a small heater, it was a toasty 22C inside the shack.

Tuesday, April 26, 2022

Australian shortwave broadcasting back on the agenda?

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.

Saturday, April 23, 2022

Appeared on ABC RN Download This Show

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. 

ttyUSB0 for IC-7300 missing on Ubuntu 22.04

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>

After a reboot the /dev/ttyUSB0 device is there and wsjt-x is all working again.

Friday, April 08, 2022

IC-705 remote control on macOS and iPadOS

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.

Wednesday, April 06, 2022

New version of iOS App WSPR Watch with 3D visualisation of spots

There's a new version of WSPR Watch for iOS which builds on the recent improvements to spot data analysis and graphs. Here's low noise master VK7JJ's spots on the graph:

(Click to enlarge). I had a wild idea that it might be nice to plot spots in 3D with x for time, y for SNR, and depth for distance away. This 3D plot is in the latest version:

On an iPhone or iPad you can rotate and zoom the 3D plot and I have to say I'm impressed with how fast Apple's SceneKit framework is at rendering 3D data.

My thanks to the beta testers and for encouraging emails during development.

Monday, March 14, 2022

A two valve regenerative receiver for 40m from Stephen, VK2BLQ

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!

Thursday, March 03, 2022

Raising an antenna support with a drone

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.

Tuesday, March 01, 2022

ABC Digital Radio Mondiale transmission on medium wave

The Ballarat 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:

Saturday, February 26, 2022

Appeared as a panelist on ABC Download This Show

This week I was invited to be a guest on Marc Fennell's Download This Show. Marc must be the busiest person in media but he still has time to put together a very professional radio/podcast show every week.

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.

Tuesday, February 22, 2022

QJ-PS30SWI low noise switching power supply with "noise offset" feature

In my pursuit of low receive noise I've been using a linear power supply but the one I have makes a loud audio hum sound that is a bit annoying. Searching for low noise switching power supplies I stumbled across the QJ-PS30SWI which I purchased for AU$120 from AliExpress.

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.

Wednesday, February 16, 2022

Command line WSPR receive with weakmon

Work to reduce noise here at Drummond has been going well and,  yesterday during a voice contact with WSPR reception leader, Phil VK7JJ, he alerted me to the fact that I was on top of the leaderboard by distance. By a fair margin too.

My iOS app, WSPR Watch, displays WSPR spots pulled from 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.

Changes I've made

  • Updated the to explain what my fork is about
  • Running under Python 3.9.7 I struck a number of exceptions during decode all complaining about things that should be integers but instead were floats. I've fixed these as I've seen them but there may be more. (All in
  • Phil, VK7JJ, pointed out that transmit maidenhead locators were incorrect. I've included a fix by Ross, EX0AA.
Since moving out of the city and receiving WSPR I've had some wonderful emails from people astonished that I was able to pick up their 200mW beacons from 16,000km away. They ask what magic I'm using - the answer is a quiet location and hunting down every bit of noise.

Thursday, February 03, 2022

Set up OpenWebRX at Drummond

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. 

To answer Paul, and other's question - no it's not publicly listed as my IP isn't fixed and it will be frequently off line.

Great work by the OpenWebRX developers!

Sunday, January 23, 2022

Using an IC-705 remotely from macOS using SDR-Control

It is hot in my shack here at the moment and I can't stand it in the shed for more than a few minutes so I decided to buy a new macOS app called SDR-Control and try the IC-705 remote feature.

Set up was easy but you do need to note the IP address given to the radio over Wifi (it would be lovely if the software could find radios on the network).

My shack is a fair way from the house and the two are linked with a Google Wifi mesh network. Despite the multiple hops control, audio and the waterfall all work well.

Sound on the Mac laptop sounds excellent and the waterfall is quick to update. Note that you can't show the whole band, only the centre mode works. Like on the radio, you can click on a signal to tune to it.

I'm still learning how to use the software, parts of it are not quite what I expect, the user manual is here.

My only complaint so far is the difficulty of tuning. It looks like it supports the mouse wheel but I'm on a laptop. I wish there were a set of keyboard tuning up down step commands. I asked the author Marcus about this and he said it was not possible directly but you can make keyboard commands to step up and down and another to set the step size.

Some of the user interface is not very "Mac like":

Some of these squares are on/off buttons, others, (like band and mode) are drop down menus. Right clicking on many of these squares does other functions.

I hope Icom releases an update to the IC-7300 with network access (both Ethernet and Wifi please).

My congratulations to the author Marcus for an good piece of Mac software. It looks like a version of the software for Flex radios.

Saturday, January 15, 2022

An off centre fed dipole antenna for more bands

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).

Wednesday, January 05, 2022

Another antenna improvement - more height

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.