I missed the last QSO Today Expo and heard that there were numerous technical glitches. Eric Guth (4Z1UG) has repeatedly described that experience as one of the most stressful in his life. He is making sure that this Expo will run smoothly by keeping all of the presentations and experience on the same platform. Eric is an amazing fellow and has gathered an outstanding group of speakers (over 90, I believe) and has made it so that if you can’t attend live, you can watch the presentations, on demand, for 30 days. Here are a few details from the QSO Today Virtual Ham Radio Expo site:
QSO Today Virtual Ham Expo
Opens: August 14th, 00:01:00 UTC or August 13th, 5:01 PM PDT
Full Registration is $10.00 US – includes full access to the Expo, including presentations, 12 subject video lounges, and to the 30 day on demand period.
Full registration will increase to $12.50 at the door when the Expo opens.
Free Registration is limited to lobbies, exhibition hall, exhibitor booths, and prizes offered by exhibitors. If you already have a free ticket, you can upgrade with the button below.
By Evgeny Slodkevich, UA3AHM/OH5HM, and Dieter Kuckelkorn, DL1DBY
When going to an outdoor camping trip, we will find that in many parts of the world there is no cell phone service avail able in the back country. To make matters worse, in these areas there is almost never a VHF/UHF ham radio repeater in range when we need wide-area coverage. Apart from strictly local communications using VHF/UHF simplex radio, how do we send messages to friends and family over great distances? How do we call for help? A similar problem can even arise in an urban environment if a major disaster strikes like the break-down of the power grid.
In activities like back country trips in areas without cell phone coverage or in a widespread emergency with the loss of our normal means of communication we can use satellite phones, but this technology is very expensive, requires subscriptions and there is no guarantee that the complex infrastructure of satellite communications will work under all circumstances. The obvious solution for Ham Radio operators will be to switch to shortwave communication using battery operated radios and often NVIS modes of operation. NVIS stands for Near Vertikal Incidence Skywave, which means transmitting with special antennas straight up to communicate with other stations 30 km to 300 km (20 to 200 miles) away with low power – which would be the most useful communications distance if help is needed. We could use SSB voice communications, but this requires that the person we want to reach is sitting constantly at his or her radio to be able to receive the message. This can be a problem: In a real emergency we probably won’t have time for this. We could instead use capable digital modes with automatic message handling capabilities like JS8Call, but these require notebook computers or other complicated setups in the field which consume a lot of energy and can be difficult to recharge off-
grid on a reliable basis.
Evgeny UA3AHM/OH5HM and Sergej UA9OV have developed another mode of digital shortwave communications, which aims to be easy to use, capable and – most importantly – friendly to the operator’s resources. Apart from a low power battery operated transceiver and a small digital interface, only an Android smartphone is needed, which can be recharged with cheap and readily available consumer-grade solar chargers. Evgeny and Sergej have created an app called “HFpager” which allows to use the smartphone’s sound chip to encode and decode audio signals in the SSB audio passband of the transceiver – similar to PC based modes like FT8 and JS8Call. It uses rates of transmission of 1.46, 5.86, 23.44 and 46.88 Baud. Modulation is 18-tone Incremental Frequency Shift Keying (IFSK) with forward error correcting Reed-Solomon code RS(15,7) and a superblock by 4 RS blocks with interleaving.
Thank you for sharing this, Pete! Sadly, I was unable to attend live due to my schedule, so am very happy to see these excellent presentations. I do hope that things will be normal next year and FDIM will happen in person again. If you attend the Hamvention, I strongly encourage you to also take in FDIM–it is always an amazing event.
Looks like our Prayers have been answer! 160 – 10, 5 Watts, single side band using a new transmitting technique , no more DSB!
All for 80 bucks (includes 3 band modules)
The v. III version debuts a novel firmware scheme for our Si5351A/MS5351M VFO which allows a move away from DSB transmission to SSB, by a new process we are calling AFP-FSK (Audio Frequency Processed-FSK).
Many thanks to Pete (WB9FLW) who shares the following article by Bob (KD8CGH) regarding the uSDX transceiver kit.
I reached out to Bob who has kindly given me permission to share his article on QRPer:
An Introduction to the uSDX
by Bob Benedict (KD8CGH)
There is a new open source, home brew multi band, multi mode QRP transceiver that grew out of the QRP Labs QCX. Through some serious wizardry it retains an efficient class E RF amplifier for SSB and digital modes. It crams impressive SDR capabilities into an Arduino.
This has an interesting international development process conducted on https://groups.io/g/ucx/topics with contributions by many, including the usual gang of suspects: Hans Summers G0UPL, Guido Ten Dolle PE1NN, Barbaros Asuroglu WB2CBA , Manuel Klaerig DL2MAN, Kees Talen K5BCQ, Allison Parent KB1GMX, Jean-Marie T’Jaeckx ON7EN, Ashhar Farhan VU2ESE, and Miguel Angelo Bartie PY2OHH. I apologize to the many others whose names I didn’t list. A summary is in the WIKI https://groups.io/g/ucx/wiki.
The basic work uSDX appears to have been accomplished by Guido Ten Dolle PE1NNZ. It uses pulse width modulation of the PA supply voltage to transmit modes other than CW while retaining class E efficiency and uses a direct conversion SDR receiver.
The basic idea behind Class E nonlinear amplifiers is that transistors have little loss when they are switched fully on or off. The losses occur when devices are limiting power flow in linear amplifiers. The idea behind a Class E amplifier is to use transistors in a switching mode to generate a square wave to drive a resonant circuit to generate RF power.
This method is used in the popular QCX QRP CW transceiver kit line developed by Hans Summers and sold through QRP Labs https://qrp-labs.com/. More than 10,000 of these great transceiver kits have been sold (I built one). There is a good discussion of the circuit and particularly of the class E amplifier in the excellent QCX documentation https://www.qrp-labs.com/images/qcx/assembly_A4-Rev-5e.pdf.
The QCX was the base for the QCX-SSB which starts with a QCX and modified the circuit and software to add SSB capabilities. The wizardry that Guido accomplished uses pulse width modulation of the PA supply voltage to control the amplifier in an Envelope Elimination and Restoration (EER) technique https://core.ac.uk/download/pdf/148657773.pdf. To generate SSB a DSP algorithm samples the audio input and performs a Hilbert transformation to determine the phase and amplitude of the complex signal. The phase changes are transformed into temporary frequency changes which are sent to the clock generator. This result in phase changes on the SSB carrier signal and delivers a SSB-signal with the opposite side-band components is attenuated.
On the receive side a direct conversion SDR receiver is used with the I and Q signal digitized and all further processing carrying out digitally. Attenuators are included to help not overload the ADC range. Documentation is at https://github.com/threeme3/QCX-SSB . In addition to a good description of the theory and hardware mod there is also a good description of the software command menu.
From there development took off in several directions. One is by Barbaros Asuroglu WB2CBA and Antrak that uses through hole components (mostly) and replaceable band boards that hold the low pass filter and band dependent class E amplifier components (an inductor and capacitor). Barb also includes boards designed to be a case top and bottom, battery pack and a PA.
I built the variant designed by Barbaros Asuroglu WB2CBA and I’m pleased with it’s performance. I ordered 10 main boards and 40 LP filter band boards PCBs from PCBWAY, but now you can also purchase single boards sets from https://shop.offline.systems/.
In an example of hams collaborating at its finest, Hans Summers announced on 9/11/2020 that his new QCX mini product, a QCX in a smaller package, will include a daughter board that can be used to give the QCX mini a uSDX like SSB capability. The QCX mini has the same circuit as the QCX but uses SMD components packaged it into a two board stack that is less than half the volume of the original QCX. The mod is unsupported by QRP-LABS but may be supported by the uSDX group.
QRP Labs has just announced the QCX+ which as the name implies is an upgraded version of the very popular QCX line of transceivers
To date almost 10,000 kits have been sold, here’s a brief overview of the the differences and new features made to this popular Transceiver.
The QCX+ is the almost same circuit as the QCX, with two very minor changes. QCX+ runs the same firmware as QCX, and has identical operational and performance characteristics. QCX/QCX+ firmware will always be compatible with both the QCX and QCX+. The evolution of QCX to QCX+ provides several improved features in physical layout, as follows:
1) Physical layout of controls and connectors
2) Optional enclosure
3) Additional and changed connectors
4) More spacious PCB, more than double the board area, with less densely packed components, and more test/modification points
5) Improved heatsinking
6) Three minor circuit changes
7) No microswitch key
Price has gone up slightly to $55, still no other QRP Transceiver on the market today comes close to the features offered by the QCX+ at this price point.
Many thanks to QRPer, Pete (WB9FLW), who shares the following sneak peek video of the new IC-705 transceiver from Amateur Logic TV with guest Ray Novak from Icom America:
Pete also notes that Ham Radio Outlet’s price has been announced a the 2020 Orlando Hamcation. According to two members of the group, the pre-order price at Hamcation is $1,175 US–the price will increase $100 after Hamcation.
Availability is still unknown: retailers and Icom have not committed to firm delivery date yet other than noting it will be sometime in 2020.