On Sunday I drove two hours to get to the Shepparton Hamfest. A little tiring but an excellent show that was both well attended and had lots to see and possibly buy.
VK3ZYZ had a display of his Arduino based VFOs which he sells as kits but also has built into radios including Codans and even an IC-22 (that brought back fond memories).
There's information and source code available via the SADARC website projects page. The club also has excellent forums with more discussion and information.
I came away with just a few parts including these nice honeycomb trimmer capacitors.
It was great to catch up with radio friends including VK3EB, VK3ASE, VK3NE and VK3CCR (the last two from the Macedon Ranges Amateur Radio Club). Warm congratulations to the Shepparton organisers for a fantastic day.
It's 7C in the shack tonight so I decided to set up the IC-705 and use it remote from the warmth of the house. The client software on macOS is SDR-Control and I was using AirPods bluetooth headphones.
Even running just 10W reports were all good although Graeme, VK3NE, mentioned a bit of boomy audio.
The main issue is the delay when switching between receive and transmit - I doubled with other stations several times. It was mentioned that my final words of an over were chopped off so I think that I need to not switch back to receive for a few seconds after ending what I was saying - perhaps there's an audio buffer to send.
The IC-705 is an amazing radio and it's great that 10W with a good antenna is enough to be easily heard by other stations. Joe, VK3MAB mentioned that I was 10dB over S9.
You can join the MRARC nets if you are in Victoria, Australia too!
We have 6kW of solar panels here but it's important to know when the sun is shining on them so I can use that power to charge the car or dry clothes. In recent months I've been learning Apple's SwiftUI and one of the gems is the new Charts View. Here's how it looks:
This wonderful chart is created with very little code:
It was a pleasure to assist at an event organised by ABC Friends - southern bayside. The topic being discussed was "The ABC Past, Present and Future" and hundreds of people turned up on a cold and somewhat damp evening.
Great to catch up with Zoe Daniel and Dr Gael Jennings. Good to meet John Faine for the first time.
The discussion was wide ranging and animated. It's great to see the deep love for the ABC from the community. ABC Alumni support the wonderful efforts of ABC Friends.
After competing in GovHack in 2017 I became heavily involved as a volunteer for a few years. After a break and a move to Melbourne I volunteered to help with GovHack in Victoria.
GovHack encourages software projects that make use of open government data. It's a wonderful contest that lets teams come together and do a quick project in one weekend.
I was tasked with taking photos and enjoyed the challenge of photographing groups.
As a volunteer it was a tiring weekend, I'm not used to standing up for long periods and talking to lots of people. Overall, very rewarding and I look forward to the state and national awards ceremonies in the months ahead.
I'm on a bit of a retro transmitter trip at the moment. Armed with some low profile 3.6864 crystals I built the "Simplex Sidebander" described in the first volume of Drew Diamond, VK3XU's wonderful "Radio projects for the radio amateur".
The transmitter is simplicity itself. An NE602 with a crystal pulled up in frequency produces double sideband that goes through a 4 crystal bandpass filter. Three RF gain stages produce about 4W out. The final is a low cost IRF510. Mic amp is a 741. Here's how mine looks:
Despite trimming the oscillator crystal I couldn't get decent sounding sideband out of it. The reason is that the little crystal wouldn't pull high enough. Acting on the advice of SmartFriends™I replaced the single crystal, first with two and then three of the little ones and in the end with three larger crystals which seem to pull more. In the end I have a full size polyvaricon for tuning:
Drew warns that the whole thing needs to be in a shielded box and I can attest to the fact that when attached to my antenna it takes off magnificently.
The exciter itself seems very narrow to me - here it is fed into a local SDR.
Off to the shops to buy a tin of biscuits... (to get a tin to put it in).
Boxed up and it no longer takes off when connected to the antenna.
I have a bit of instability as you can see in the dips in the AM test signal here:
I was horrified when I looked at the spectrum coming from the minion on 80m so clearly a low pass filter is needed. I used the notes from GQRP on low pass filters for my design and it looks good when swept.
My build is not very compact and indeed it's almost the same size as the whole transceiver.
I quite like these boxes, purchased on AliExpress and plan to make low pass filters for 40 and 20m as well.
The filter on a spectrum analyser shows that it's 3dB down at 5.16Mhz and the first harmonic, at about 7MHz would be down 25dB at least.
The QRPVer QRP Minion SDR transceiver I ordered on Feb 3, has just arrived (June 13). So far I'm very impressed. It's very compact, with a beautiful display and enough audio power to be heard clearly.
The unit has a USB port for CAT control and software updates. There's also audio line in and out for digital modes.
I plugged it in to a 40m dipole and it receives well. I called in to the morning net on 7.1Mhz and was given a 5/5. Another station, unprompted, popped up to say that my audio sounded good.
Here's some video of the Macedon Ranges Amateur Radio Club 80m net with comments from other stations. Note the PL-259 connector on top to show the size.
The company that makes these is in Ukraine and I'm sympathetic to the obvious disruption that's taking place over there. It's amazing that they can keep an export business going. The purchase process was not smooth and, hearing nothing, I thought perhaps my money was gone. Yurii asks that you pay with PayPal and select "friends & family" option which saves him a fee but also means you can't reverse the transaction if the goods don't come. I would advise purchasers to add 3% and pay normally.
Anyhow, all good in the end although my unit arrived with damage to the rear panel but otherwise working well.
I've written to Yurii to ask about ordering a replacement rear panel. So far, no reply. In the mean time, I've made a replacement rear panel. I skipped the power switch as simply unplugging the 12V is fine for me.
Yikes, no low pass filter!
The manual isn't explicit but another multi band radio from QRPver mentions that the low pass filter is at 30Mhz and external filters should be used for other bands. I can confirm this:
Transmitting on 80m CW the spectrum shows that the first harmonic is down just 4.3dB.
The waveform on CW looks rather bad.
I did use it into a resonant 80m dipole so there would have been some filtering but this is a concern and an external low pass filter is definitely required for legal (or responsible) operation.
Update from the next post, after building a low pass filter for 80m, the CW waveform looks much better:
A question about tuning
When transmit is keyed the display shows audio level, power out and SWR - very convenient!
Tuning needs a fixed RF output which could be created in CW mode or with a tone on SSB. There is an indicator saying "Tone OFF" here. The user manual describes this as "Tone tune Indicator" and one of the features listed is "Transmit tone to tune the antenna tuner, amplifier."
I can't see how to turn on the tuning tone. Perhaps it's done via CAT from an amplifier? Interested to hear if anyone knows.
There are some more detailed reviews here. The current price is US$410.00. (Microphone sold separately).
Here I describe how I've been able to use a SDRPlay RSP1 clone with CubicSDR via SoapySDR on Linux Mint (a Debian/Ubuntu derivative) without using any proprietary software from SDRPlay. This is the device I'm using in this post:
I fully realise that these clone devices are controversial but they are now widely available at low cost and are a copy of an old device, soon to be no longer supported by SDRPlay.
I respect the folks at SDRPlay and have bought from them in the past. There is some criticism of their closed source driver which runs as root and I think it's great that there is an open source alternative.
Clicking on the Mirics device will hang CubicSDR.
Unfortunately, the software that ships currently on Linux Mint doesn't work out of the box but some good work by third parties have made it possible with a bit of messing about as I document below.
On a fresh install of Linux Mint 21.1 Cinnamon 64bit on an x86 laptop.
If you plug in the device and look at loaded kernel modules you’ll see two msi… modules like this:
lsmod |head
Module Size Used by
msi001 20480 1
msi2500 36864 0
To stop these loading, and capturing the device, we need to blacklist them.
sudo nano /etc/modprobe.d/blacklist.conf
blacklist msi001
blacklist msi2500
sudo reboot
sudo apt install cubicsdr
Note that this installs a bunch of soapysdr packages:
That soapysdr0.8-module-mirisdr module has issues and needs to be replaced. While it’s tempting to `sudo apt remove libmirisdr0` this will remove all the other soapy stuff which we need.
We need to build a new version of libmiri and the SoapyMiri driver:
I build lots of little electronic projects, some work well, some work poorly, some just don't come to life. After a few failures I lose confidence and a good way to get my home made mojo back is to build a kit. A kit for a "My first transceiver" MFT-40 (20m also available) from Spain's QRPHamradiokits caught my eye recently.
The designer references Peter, VK3YE's "Beach-40" which I've also built but has improved on the design. Peter's simple circuit suffers from feedback during switching from transmit to receive and uses a diode ring mixer rather than an NE602.
"The MFT-40 incorporates a DC (direct conversion) receiver with a 3-stage front-end passband filter, followed by a balanced mixer, an audio preamplifier and filter using an operational amplifier, and an output amplifier for driving a loudspeaker. The local oscillator is based on a 7.2 MHz ceramic resonator element that allows coverage of a part of the 40m band.
The DSB (double sideband) transmitter uses a DSB generator with input from an economical electret condenser microphone and three stages of amplification which produce 3-4W to the antenna."
The kit is well presented with a top quality board that cleverly can be cut in half to make separate receiver and transmitter sub-boards if you wish.
The instructions are good (and you can see the schematic there) but the designer can't quite make up his mind about the best order to add components. Parts lists are presented both sorted by value and again but sorted by number (R1, R2, etc) which doesn't always group by where they are located in the circuit. Also there's the suggestion that new constructors might just build the receiver first - probably a good idea but maybe there could be a separate kit for a receiver only.
There's some minor errors with carrier suppression pot P4 in the text actually being P3 on the schematic and mic gain P3 actually being P2 on the schematic but it wasn't hard to figure this out. My kit had an incorrect component that was easily found in my junk box.
In use, the receiver works very well although, not-unexpectedly, tuning is very sensitive. The transmitter perhaps suffers from not enough mic gain - the supplied electret mic directly drives the input to the NE602 mixer. (I don't know where QRP Ham Radio Kits managed to source through hole NE602s - they are very hard to find these days).
Here it is in use:
I spotted the biscuit tin while shopping in Kyneton. The size is perfect for this project and others for sure. Drilling was easy. The biscuits are also very nice, if a bit sweet for my taste.
SDR++ continues to impress as an excellent SDR client. One terrific feature is that it has a server mode built in. You run the server side on the command line with --server after it and then run SDR++ from another machine to connect to it.
I'm running the server in my low noise shack and using the client in the house. They are connected via wifi at both ends but operation and reception is smooth.
To record this and capture the audio on macOS I use the free VB-Cable to connect the output of the receiver to the built in screen recorder. The problem with this is I can't hear the audio while I'm recording so it's hard to tune around. The solution was to run an audio recorder/editor (in my case Sound Studio) which has a feature to pass through input audio so I can monitor.
