DUBUS 2024

DUBUS 4-2024 Vol-53

Editorial.
Nimbostratus Rainscatter: 47 GHz VUCC in One Week
by Hugh Duff, VA3TO, and Peter Prabucki, VA3ELE
This paper discusses the use of a previously unexploited mode of propagation to archieve VUCC (ARRL award) on the higher microwave bands when there are no LOS paths to adjacent grids. Most of us are familiar with rainscatter on 10 GHz and the benefit of extending the DX range, offering QSO opportunities that are not usually workable by tropospheric propagation. Tall summertime cumulonimbus thunderstorms offer contacts beyond 100 km ... [VUCC Challenge on microwave bands | Low Ceiling Nimbostratus Rain | 47 GHz Experiments].
High-Precision (<0.01°) Az/El Traking System for 10 GHz and up
by Ivan De Cesaris, IZ0JNY
In this article I would like to illustrate the solution I chose for the creation of a precision rotator system for EME use at frequencies from 10 GHz and above. I did all the assembly by myself and a lot of DIY for the various components used. The heart of this precision rotator controller is based on the driver board and tracking software suite developed by Jose, EA3HMJ, and a really impressive work, available for everyone on GitHub. Depending on the encoders used, and the quality of the entire mechanical structure, this rotator system can reach a precision of up to 2/3 thousandths of a degree ... [Project description | Overview | Slew drives | AZ/EL encoders | System assembly | Alignment | Sun/Moon noise measurements].
Software to assist Analysis of Antenna Performance using Solar Drift Scans
by Charlie Suckling, DL3WDG, and Bob Atkins, KA1GT
Most EME operators use measurements of sun noise to verify the combined performance of their antenna and receiving systems. This is usually limited to measuring the ratio of maximum sun noise to cold sky (Y-factor). In some situations, for example when troubleshooting antenna performance, it is very useful to measure the 3dB beamwidth and sidelobes of the antenna, to check for deficiencies in feed illumination, feed position, surface geometry and reflectivity of the dish surface. At higher frequencies ... [Program design and capabilities | User guide | Inputting data | Practical considerations].
Another 1296 MHz Lightning Scatter Event using MSK144
by Rex Moncur, VK7MO, and Brodie Churchill, VK3MAP
Somewhat to our surprise another 1296 MHz lightning scatter event occurred on 24 August 2024. This event was even better than that reported in DUBUS 2/2024, page 111, in that 4 QSOs were completed in an hour and none were impacted by aircraft scatter ... [Path | Doppler variation].
Experiments with a 5800 MHz GaN SSPA
by Harke Smits, PA0HRK
The need for long range control of First Person View (FPV) drones has made solid state PAs (50W range) for the 6 cm band available at affordable prices, a little over 200 USD. Refer to some well-known auction sites. Unfortunately, these PAs are not just used to control drones, but also contain a jammer to prevent it. If the jammer can be silencied it would be nice to investigate if these PAs are suitable for 5760 MHz use. This report presents some lab experiments with the YPM5850B a 50W SSPA ... [Path | Doppler variation].
PTFE (Teflon) VHF Antenna Insulators by George Chaney, W5JTL (SK), revisited
by Hartmut Kluver, DG7YBN, with Joe Burke, WA8OGS, and Richard Kreuter, WC8RK
We all know that PTFE (Teflon) is an almost perfect insulator, but it also has some other unique properties in its virgin form. W5JTL found that he could put a flanged PTFE bushing into a boom hole and expand a centre hole with a mandrel to lock it in place after a slightly smaller antenna element was installed ... [How it all began | Testing boom | Measurement].
47 GHz Dual Mode Feedhorn with Internal Transition to WR22 Rectangular Waveguide Interface
by Jeffrey Pawlan, WA6KBL
Prior articles by this author presented the design of 10 GHz and 24 GHz dual mode feedhorns. Their preformances were tested and found to be almost identical to the simulations down to the -50dB level. A strong need has been expressed both in Europre and the USA for a high quality feedhorn optimized for operation at 47.1 GHz ... [How this feedhorn works | 47 GHz design | Simulated performance | Measured performance | Antenna assembly drawings].
QRPP Moonbounce on 1296 MHz is possible
by Jac de Bruijn, PA3DZL
At first you think, for making QSOs via the Moon, you need a large antenna and a lot of power. That is absolutely not the case. Nowadays, by using the digital Q65 modes in WSJT-X, you can make QSOs even with a very small setup ... [Station description].
REF / DUBUS European EME Contest 2024 - CW Results.
Microwave Spain and Portugal.
Microwave Europe.
Microwave Japan.
Microwave North America.
Tropo Reports.
Aurora News.
2m TEP News.
6m & 4m News.
News & Comments
Contest, Expeditions, Beacons update, Comments, Classified Ads.

DUBUS 3-2024 Vol-53

Editorial.
A High Efficiency Solid State kW amplifier for the 2m band with Planar Baluns
by Sylvain Klingebiel, F6CIS, and Michel Bourdon, F6DZK
A high-efficiency 144 MHz LDMOS 1kW PA using printed planar baluns has been designed with the aim to reduce the power dissipated by the LDMOS transistors as much as possible and thus increase reliability. These planar baluns also make the construction of tge SSPA simpler and more reproducible. The drain currents can be measured separately which makes it possible to check that the push-pull is correctly balanced and that maximum drain current is not exceeded ... [Printed baluns | Thermal characterization | Optimizing efficiency | Circuit diagram | PCB | Measurement results].
Phase Noise Measurement Revisited: Revisited
by Dennis G. Sweeney, WA4LPR, and Jim Davey, K8RZ
The phase noise measurement paper Phase Noise Measurement Revisited recently published in DUBUS suggested that high performance computer sound cards matched with the appropriate software might be used to measure phase noise. At the time of publication, suitable software had not been found. As a result of the DUBUS publication, Harke Smits PA0HRK suggested using the Focusrite Scarlett Solo sound card with DG8SAQ's AudioMeter software to do phase noise measurement. This paper outlines our efforts to use Focusrite sound card and AudioMeter to do phase noise measurement ... [Sound card interface | Software | Analysis and configuration | Measurement].
Aircraft Scatter: New perspectives, questionable concepts (part 2)
by Nils Schiffhauser, DK8OK
Is it possible to track the path of aircraft using WSPR log data? And how can this be proven or why is this practically impossible? In the concluding second part, Nils Schiffhauser, DK8OK, concentrates on Doppler traces and their levels ... [Doppler, like a fingerprint | Identify curves | Distance role | Examples].
241-250 GHz Transverter. The Top Band (1mm) is within reach
by Andrew Anderson, VK3CV/WQ1S
In this article I describe a new approch to getting on the top amateur radio allocated band at 241-250 GHz without the use of high order external multiplier chains and passive mixers. The approach is based on a newly released chip, the TRA-240-091 from Indie Semiconductor (formerly Silicon Radar). The chip covers the entire amateur primary and secondary allocations in the 1mm band from 241-250 GHz. The chip will actually cover 222.5-267.5 GHz ... [Circuit diagram | Circuit theory of operation | Software operation | PLL configuration | PCB construction | Testing and optimization].
Q65-15C on Auroral Es Backscatter and other Auroral Propagation
by Rex Moncur, VK7MO, and Brodie Churchill, VK3MAP, and Dr Andrew Klekociuk
Over the past 18 months we have been conducting test on Auroral Scatter with Q65-15C that have produced over 4000 decodes mainly between VK7MO and VK3MAP. The sensitivity of Q65-15C with its ability to measure Doppler and signal levels and record files has proved to be very useful for not only QSOs but also for identifying the characteristics of various type of propagation ... [Aurora Es forward-scatter | Aurora Es back-scatter | Setting for reception].
Aurora News.
Tropo Reports.
Microwave North America.
Microwave Japan.
Microwave Europe.
Microwave Spain and Portugal.
News & Comments
Contest, Expeditions, Beacons update, Comments, Classified Ads.

DUBUS 2-2024 Vol-53

Editorial.
Investigating the Extended Frequency Range of the WA1MBA Millimeter Wave Quadrupler
by James Morris, W7TXT
This paper discusses a qualitative investigation into the usable frequency range of the active millimeter wave quadrupler produced by Tom Williams, WA1MBA. These quadruplers are specified to operate with an input frequency range of 10 GHz to 12.5 GHz, and an output range of 40 GHz to 50 GHz. They may be used to construct beacon or CW transmitters in the 47 GHz amateur band ... [Quadrupler overview | Experiments | Results | Confirmation at 78 GHz].
DIY Low-Cost Parabolic Dish Antenna
by Flavio Robles, F5ASM
A few years ago I suggested that a dish could be made with material that can be found very easily and at a much lower cost compared to aluminium ... [Construction | Assembling | Total cost for the material].
30 THz Transmitter using a Directly Modulated Spiral Heater Element
by Barry Chambers, G8AGN
Over the summer of 2023, G8AGN and G4APV carried out a number of tests ai 30THz using the chopper wheel transmitter and SDR receiver described previously. The longest DX achieved was ... [Circuit | Test rig | Arduino functions].
Sun Activity and Radiation Temperature at 24 GHz
by Dimitry Fedorov, UA3AVR
This report is about investigations of Sun noise at 24 GHz and its connection to solar activity. This connection is important when using the Sun as source for receiver tests ... [Instrumentation | Data collection | Processing procedures].
Sporadic-E Summary 2023 - 144 MHz
by Joachim Kraft, DL8HCZ / CT1HZE
66 maps and comments for Europe, North America, Australia and New Zealand Es openings.
WRC-23 outcome - RNSS and ARS coexistence in the 23 cm band
by Attila Matas, OM1AM
The WRC-23 took place in Dubai (UAE) from 20 November to 15 December 2023, attended by 3900 delegates from 163 ITU Member States, with several ham radio operators as part of their national delegations. The WRC-23 had 19 main Agenda Items (AI) and several associated AIs, because of the "Director's Report". One of these "small" AIs was also the famous WRC-23 AI 9.1b, approved by the previous WRC-19, calling for studies on the coexistence of 23cm Radio Navigation Satellite Service (RNSS) and Amateur Radio Service (ARS) ... [Amateur service and ITU | History of 23cm band | Studies related to the RNSS/ARS 23 cm coexistence | WRC-23 impact on 23cm band].
Aircraft Scatter: New perspectives, questionable concepts (part 1)
by Nils Schiffhauser, DK8OK
Is it possible to track the path of aircraft using WSPR log data? And how can this be proven or why is this practically impossible? In two episodes DK8OK takes a now derailed discussion on this topic as an opportunity, on the one hand, to trace misguided parhs and, on the other, to bring the subject back to a more objective level by concentrating on the technical ans scientific expertise of radio amateurs ... [What WSPR data shows and what it doesn't | A thesis].
Lightning Scatter on 1296 MHz using MSK144
by Rex Moncur, VK7MO, and Brodie Churchill, VK3MAP
Some 50 lightning scatterd signals were decoded using MSK144, over a 3-hour period, when a severe lightning storm passed between us on 13 February 2024. Such a severe storm is a very rare event at our latitudes and resulted in 544.000 lightning strikes and power being lost to some 500.000 homes in Victoria ... [The event | Signal levels and Doppler Shifts | Completed QSO].
Aurora News.
Tropo Reports.
Microwave Europe.
Microwave Spain and Portugal.
Microwave Japan.
Microwave North America.
2m Evening TEP from EU to V5. First transequatorial QSOs completed after 33 years!
8m, 6m & 4m News.
News & Comments
Contest, Expeditions, Beacons update, Comments, Classified Ads.

DUBUS 1-2024 Vol-53

Editorial.
A Compact, Lightweight 2-Element Yagi for the 8m (40 MHz) Band: Design and Costruction Insights
by Justin Johnson, G0KSC
In this exploration, we delve into the design and costruction of a straightforward, 2-element Yagi antenna for the 8m band. This antenna is notable for its minimal component use, lightweight nature, and impressive performance given its size. It features a direct, 50-ohm feed and boast self-balancing properties, along with the essential grounded driven element ... [The LFA-R advantage | Design and structure | Components and performance].
Know your Parabolic Antenna better from Measurements of Sun, Moon, and Ground Noise
by Joachim Koppen, DF3GJ, team of DL0SHF
Does my parabolic dish antenna work in an optimal way? How can I measure its performance, and maybe find out what needs further improvements? These may be questions you might ask yourself when set up a new antenna or use an existing one. The obvious way to judge and improve the efficiency of an antenna, is to point it to the Sun - the radio strongest in the sky - and make its signal as large as possibile. This certainly is a practical way, but still it doesn't tell us how well the antenna works ... [How to measure | A software tool to interpret the measurements | Example | Analysis of the measured data].
The search for gravitational waves Fundamentals of reception technology
by Herbert Weidner, DL2ZC
107 years ago, Albert Einstein claimed that certain astronomical events produce gravitational waves. These were first detected 99 years later, but only in the form of short-term wave packets with limited significance ... [The atmosphere as an antenna | Properties of waves | Phase modulation | The MSH method | IQ mixer | How to search waves].
Sectoral Horn Antennas for Microwave Beacons
by Paul Wade, W1GHZ
Microwave beacons are really useful for monitoring propagation or just for reassurance that your gear is still operationg. For rovers, they also provide an accurate heading and frequency ... [Horn antennas aperture | 24 and 47 GHz antennas | Lower frequencies].
Want more? QSY to 134 GHz
by Andrew Anderson, VK3CV/WQ1S
Following single band 122 GHz transverter first described in 2019, here is an updated design that covers both the 122 GHz and 134 GHz amateur bands. More than 500 of the original 122 GHz design PCBs have been produced and have found their way to every part of the world ... [Transverter complete circuit diagram | Theory of operation | Software operation | PLL configuration | Construction | Testing and adjustments].
An RF Current Probe for HF/VHF/UHF
by Edward A. Richley, KD8KZ
Methods for obtaining an accurate measuremen of RF current are not often covered in the amateur literature, yet this capability has many possible uses. In contrast, RF voltage measurement is common and well-known and often consists of a resistor network with some capacitance added for frequency compensation. Current measurement, on the other hand, can be very useful for making an in-circuit impedance measurement, or by combining with a voltage probe to make a directional coupler ... [Circuit design | Construction | Performance].
23cm EME with ADALM PLUTO
by Mirek Kasal, OK2AQ
Analog Devices has been offering an SDR-transceiver with very interesting features, the ADALM PLUTO (Active Learning Module PLUTO SDR). It is intended primarily for students who, thanks to its open architecture, can program the transceiver for most modulations and coding used in communication systems and thus study the physical layer of these systems in the frequency range 325 MHz to 3.8 GHz ... [Frontend | Software | Experience of operation].
Microwave Europe.
Microwave Spain and Portugal.
Microwave North America.
Microwave Japan.
Tropo Reports.
Aurora News.
6m & 4m News.
News & Comments
Contest, Expeditions, Beacons update, Comments.