Month: October 2014

CQWW SSB 2014 fail

I wanted to take part in CQWW SSB this year, as usual in the SOSB QRP category. This year I chose the 10m band as propagation was looking good, and I was planning to install another antenna especially for this purpose. Unfotunately, the weather defeated me in a big way. The vertical  was already damaged for some time and I didn’t get around to fix it as the 41m long OCFD was working just as good. My plan was to fix the vertical and to install a 10m tuned horizontal dipole aimed at Europe and NA in the evening before the contest, but it was cold and it was still raining. So, I decided to do it during the contest when Asia propagation starts to fade away and NA doesn’t kick in yet; after all, the weather forecast was better, I will need a break anyway at a certain point, and I had the OCFD that was enough to work the stronger stations. Well, I can definetely say now that I won’t ever trust again the weather forecast. On Saturday morning the wind was really strong, so strong in fact that it broke one arm of my OCFD, an antenna that was holding in all kinds of weather for 3 years. This happened about 30 minutes into the contest, I tried to use the vertical but no luck, I...

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Portable SDR transceiver with integrated VNA and GPS

The field of amateur Software Defined Radio is moving quickly nowadays and the latest spawn is something really interesting: a portable SDR transceiver that integrates a Vector Network Analyzer and a GPS module. This thing covers up to 30MHz (plus 144Mhz band) and is open source, so basically it can do whatever you want it to as long as you’re good with software and can hack the hardware a bit. The brain is a STM32F429 microcontroller running at 168MHz; while it’s integrated ADC’s are really modest (12-bit, 7.2Msps) compared to other SDR equipment out there, they can offer good receive performance in this application. It also comes with a nice color TFT LCD and everything you will ever need to know about it can be found on it’s Hackaday page. The interface is a love it or hate it kind of thing: it’s just a rotative encoder with an integrated push button. That’s it, all the options can be (sooner or later) accessed from it. While initally I thought it was the most useless thing ever created, I gave it a second thought: hey, this small box of smartness is supposed to be a portable equipment and it very rarely happened to me to need more than 3 controls while I was backpacking with any of my radios. There is a USB present if you want a real control...

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An amateur radio beacon will fly to the moon and back

Also called the 4M, Manfred Memorial Moon Mission will travel to the Moon and hopefully back to Earth aboard the Chinese Long March 3C rocket. Its payload will include a JT65 beacon that will transmit shortly after departure on the 2m amateur radio band. Transmission will include the callsign LX0OHB as well as various info: elapsed time from launch, power supply parameters, temperature and dosimeter readings etc. Transmitter is 1W output into L/4 monopole. For those that want to monitor the beacon, here’s the required info: – TX freq: 145.980MHz, +/- 2.9KHz variation depending on temperature, +1KHz/-2.2KHz Doppler shift– departure time: October 23 2014, 17:59 UTC, expected on air at 19:17 UTC– special JT65 software version from here.– extra info here. More details about the project, on the AMSAT-UK...

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Noble NR4SC – monoband QRP TRX for 70MHz band

Noble NR4SC is a new transceiver for the 70MHz ham-radio band, supporting SSB and CW and offering an output of 10W. It’s a simple design with good usability, easy to learn and to use. The receive section is based around a single-IF (10.7MHz) topology with diode ring mixers (RFMX-1 ? can’t find any info on them), 8-pole crystal filters (3Khz SSB, 500Hz CW) and AGC in the IF section, with a DDS for a VFO. This recipe is pretty basic as far as design goes, but it can provide decent performance if executed properly – the key points being a low DDS spur and phase jitter level and a high mixer drive level. Can’t comment more on this until I see schematics, but for now these aren’t released. Edit: Rob PE9PE from Noble Radio was kind enough to clear things up for me, the VFO uses a Minicircuits JTOS-100 VCO controlled by an Analog Devices AD4001 PLL, wich has an AD9850 DDS for a reference. Nice low-jitter solution ! BFO is another AD9850, good enough for that job. Here are the released specs though: 1) SSB/CW 2) 10 Watt output power 3) Built in Iambic keyer 4) Analog S-meter, not a bargraph. 5) RIT 6) SPLIT 7) Variable Speed Tuning VST 8) Wide and Narrow filter 9) Fast and Slow selectable AGC 10) Output to key an external Amplifier...

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