VHF, UHF and Microwave Record Table - the latest table of records is available from the VHF SA Record page. Click here to get a copy. Compiled and updated by Paul, ZS6NK - latest version 31 October 2019. Updates to zssixnk@gmail.com
Focus on VHF and Above 12 January 2020
Audio version
VHF news is a little scarce this week. It seems like most have returned to work after the holidays. There has however been some activity on the VHF and above bands.
Band conditions inland have not been that great, but that has not stopped activity nor amateurs being active. Rickus ZS4A has been testing JS8Call on 2m using just 10w into a simple horizontal turnstile antenna. Both Carl ZS6CBQ and Pierre ZS4PF have received the signals. Be on the lookout for them on 2m.
On Saturday the West Coast amateurs had another fox hunt. Looking at the hype on the WhatsApp group this is going to be another fun event. We hope to have another report from Charles ZS1CF in the next week or two.
Last Sunday the guys on the East Rand also had a fox hunt and the guys enjoyed it immensely.
Contrary to popular belief in amateur circles this still seems to be an activity that is enjoyed by radio amateurs. In Europe, fox hunting or Radio Direction Finding as it is called is a very competitive radio sport.
How many other clubs have a regular fox hunt? What about turning this into a local challenge amongst clubs. It can certainly be a way to get clubs to do activities together.
Tropo conditions were also great along the West Coast on Friday and Charles ZS1CF and Cobus ZS3CVB had good FM signals between Langebaan and Port Noloth.
ZS1CF_ZS3CVB.mp4 The conditions across the Atlantic was also good and PY1MHZ has been monitoring on horizontal from Brazil.
The 6m band has also been experiencing some openings. On Friday Willie ZS2CC was reported by Paul ZS6NK to be up to S3 with Willie reporting Paul being S9.
So listen out for those beacons and give the occasional call as well, as you never know when the bands will be open for those long distance VHF and above contacts.
I have been busy getting interfaces and software up and running to be able to do Winlink point to point on 2m packet and other digital modes on the VHF bands specifically for emergency communications use. I have had some successes, but also some challenges, mainly with software.
It is amazing how the time flies when you get that soldering iron warmed up and you toggle that keyboard trying to get software working.
How about sharing with VHF News what are you playing with? Have you tried something new over the holidays?
Please send your news snippets and information about activities on VHF and Above to vhfnews@sarl.org.za.
Focus on VHF and above is compiled, edited and presented for Amateur Radio Today by Brian Jacobs ZS6YZ.
Focus on VHF and Above 5 January 2020
Audio version
Last week we posted a link to a video of a recent EME expedition in Botswana A21EME.
What is EME? EME stands for Earth-Moon-Earth and is sometimes referred to as moon bounce. It is fundamentally transmitting a high power signal through an antenna array pointing to the moon and then the reception of this very attenuated signal on the other end. It sounds simple doesn’t it.
No, definitely not. EME is very specialised and if you want to do it properly then you need to be willing to spend a lot of time and effort and money to develop an EME station.
We need to remember that the moon is approximately an average distance of 384,400 km away from the earth and it takes approximately 2.52 seconds for a signal to get sent to the moon and back.
The moon also only reflects about 7% of the signal that is transmitted.
There are various factors that effect EME propagation.
To be able to make an EME contact, both stations need to see the moon. It does not matter whether it is a full moon or not or whether it is day or night. There are a number of software programs available that will predict the position of the moon and these programs also have the ability to control a rotator on both the azimuth (left and right) and elevation (up and down) so that the moon can be tracked and the antennas remain pointed to the moon as it moves across the sky.
Whether the moon is in Apogee (furtherest point away from the earth) or Perigee (closest to the earth) also matters. Although there is only approximately a 2dB difference in the path loss, this can be the difference between a QSO or not.
There is Faraday rotation which occurs when the signal passes through the ionosphere. The speed of rotation and polarity is unpredictable.
There is also Spatial Polarity which also affects the polarization of the signal. So you need the ability to change the polarity of your antenna as well.
There is also a phenomenon called Libration Fading which is caused by the uneven surface of the moon.
Add to this Doppler Shift as a result of the relative movement of the moon to the earth.
There is a path loss of around 250 dB for a signal reflected off the surface of the moon. So one needs to firstly transmit as big a signal as possible, by making use of the best amplifiers that you can afford, having an array of high gain Yagi antennas or a dish depending on what frequency you will be working on. You need to make sure that you minimize every dB of loss getting your signal out of your antenna.
Then again on the receive side you need to try and receive that very small signal that is returning from the moon and amplify via an antenna array and a very low noise amplifier and again minimizing the losses in your receive path. Even the type of connectors used can make a difference. This was a topic in one of our VHF Workshops last year that was presented by Pine ZS6OB.
Using WSJT software has made it a lot easier to complete an EME contact than in the past.
EME operation is probably one of the ultimate challenges in amateur radio. Certainly not for the faint hearted or financially challenged.
Here are some links to places where you can get more information:
EME on a Budget by K4MSG
Information about EME by PE0SAT
How to Use Amateur Radio Moonbounce, EME Propagation
The other alternative is talk to amateurs who are involved in EME like Pine ZS6OB, John ZS6JON, Paul ZS6NK, Bernie ZS4TX and Rickus ZS4A to name a few. All of their contact information is on the SARL call book.
Now for some other VHF news.
Over the last week, there has been some remarkable conditions on the VHF bands allowing lots of DX contacts across Europe.
Tropo conditions over the eastern part of the North Atlantic were exceptional over the weekend of 28 December 2019, allowing many stations in the UK and Ireland to make contacts with D41CV on the Cape Verde Islands on 144 MHz.
Excellent contacts were made on 70cms as well.
At 11:09 UTC on Saturday the 28th of December 2019, Ian White, GM3SEK in the south-west of Scotland managed to work D41CV on FT8 on 432 MHz extending the IARU Region-1 tropo record to an amazing 4,562 km.
It would seem as if this is not only a Region-1 record, but also a new world record for tropo on 70cm.
GM3SEK was using 100 watts and a 23 element Yagi on 432 MHz for the contact which was mostly over a sea path.
On the 1st of January 2020, the New Year was hardly a few hours old when Callum, GM0EWX on the Isle of Skye in the west of Scotland managed to work D41CV on FT8. This now extends the IARU Region-1 144 MHz tropo record to an amazing 4,776kms. For the contact, GM0EWX was using an IC7100 with 400 watts into two 15-element long Yagi's about 15 metres above ground level.
Thanks to EI7GL for this information.
Locally, it seems like the predictions for some tropoducting inland did not materialise this last week.
Let us keep monitoring the beacons to see when conditions improve to allow those long distant VHF and UHF contacts. We never know when an opening may occur.
Let us see what the next couple of weeks brings us.
That is all for this week.
Please send your news snippets and information about activities on VHF and Above to vhfnews@sarl.org.za.
Focus on VHF and above is compiled, edited and presented for Amateur Radio Today by Brian Jacobs ZS6YZ.
Focus on VHF and Above 29 December 2019
Audio version
Carl ZS6CBQ alerted us to a fantastic video that has been placed on YouTube by Chris, PA2CHR who was one of the participants in the recent A21EME expedition that was hosted by ZS6JON outside Gaborone.
https://www.youtube.com/watch?v=nVrPtuB_nbU
You can find more information about this expedition at https://hb9q.ch/2018/?page_id=1659
We will look at doing an introduction to EME in the new year.
For those interested in SSTV, ARISS will be supporting SSTV transmissions worldwide in memory of cosmonauts Alexei Leonov, Valery Bykovsky and Sigmund Jaehn.
The transmissions are scheduled from December 28, 2019, starting at 11:00 UTC, until January 1, 2020 at 18:20 UTC when the system is scheduled for shutdown.
Transmissions will be on the standard frequency of 145.800 MHz and in the PD 120 format.
The Polish ARISS Team has prepared an award for participants to this SSTV experiment. More information can be found at https://ariss.pzk.org.pl/sstv/
Now on to Tropoducting.
Pascal F5LEN has a website where he also does tropospheric propagation predictions. Pascal is continuously updating his software and Carl ZS6CBQ reminded me again of this website on a WhatsApp post on the 46 VHF/UHF Long Distance Group. Pascal now includes some prediction over land masses as well. Take a look at his website at http://tropo.f5len.org/africa/
You will see the prediction for this evening at 21:00 UTC looks favourable for inland.
Likewise the prediction for Sunday 5 January 2020 at 00:00Z
FRZS192_5Jan2020.png
Looking ahead on Windy.com shows us that there could be temperature inversion inland starting on 30 December 2019 through to 2 January 2020 and the Hepburn Charts also shows similar information.
It would be interesting to see how these predictions correlate to what we see in practice. Keep your ears open for the ZS0BET beacon which seems to be a good indicator for openings inland.
Well that’s all for this week. Wishing everyone a Prosperous New Year and great activity on the VHF and above bands.
Please send your news snippets and information about activities on VHF and Above to vhfnews@sarl.org.za.
Focus on VHF and above is compiled, edited and presented for Amateur Radio Today by Brian Jacobs ZS6YZ
Focus on VHF and Above 15 December 2019
The installation of the Bethlehem beaon
Audio version click here
The beacon was developed over a number of months and was a project that came about as a result of a VHF Workshop held almost a year ago. After that workshop a VHF Working Group was formed and the idea of developing a beacon in the Northern Karoo, halfway between Cape Town and Johannesburg was discussed. While hunting for suitable sites for the Karoo beacon, a site in Bethlehem became available and it was decided to build two beacons with the Bethlehem beacon being the test site with two antennas pointing in different directions for propagation testing. A Project plan was drafted and the SARL made funding available for the project. This allowed us to purchase two second hand Icom radios. Two Hygain Yagi antennas, a power supply and LMR400 cable and connectors were also purchased from Sam ZS6BRZ at a good price.
The antennas were assembled and tuned by Carl ZS6CBQ and Dick ZS6BUN. Rickus ZS4A built the brackets to mount the antennas to the mast and Koos ZS6KSG built the box for the beacon to live in including three fans used to clear the warm air generated by the radio and power supply out of the box.
The keyer was assembled by Brian ZS6YZ. The keyer is a simple ATTiny microprocessor with two outputs, one putting the radio into PTT mode to get the VCO running and stable before the second output switch switches the pre-amplifier to generate the CW signal. Well, that was the plan.
The single biggest challenge turned out to be the ability to generate a good clean CW signal that can be decoded by monitoring software. Both Cor ZS6CR and myself had a radio and we tried various methods to generate a clean signal. At one stage it seemed that everything we tried just caused the radio to do it’s own thing and there was no way we could kill the VCO signal let alone switch the pre-amplifier on and off. Even pulling all buffer transistors to ground did not stop the radio from transmitting. We even had advice from a master beacon builder, Ivan Stauning OZ7IS who has been the beacon keeper for the OZ7IGY beacon since 1981.
Eventually I found that switching the biasing on the power amplifier worked the best, but there were still two issues to get around. The first one was bleed through from the VCO and the second one was the noise or key clicks generated when switching the power amplifier on and off. The VCO bleed through was found not to be a problem as it was internal to the radio and with the covers on the radio, the bleed through was not picked up more that a couple of hundred metres away from the radio.
The key clicks became the problem and again everything I tried did not work. Not even the solutions discussed in the ARRL handbooks. Eventually while monitoring the bias voltage of the power amplifier and consulting the manufacturer’s data sheet for the power amplifier it dawned on me that the power amplifier only needs 5V to provide maximum output and that the bias voltage ramped up to over 6V when switching on before returning to 5V. The manufacturer of the radio has an elaborate power control circuit which was slow at responding. Well again not to slow for what the radio was designed for, being an analogue FM voice radio, but far to slow for the fast switching required to generate CW at around 12 words per minute.
The solution turned out to be a simple 5.1V zener diode to clamp the bias voltage to 5.1V. No more key clicks! Radio sorted.
We did some extensive testing and decided on an installation date of 7 December. Rickus told us that the installation date could not be before 21 November as that was the day his son Stephan ZS4SDL returned from the US. Rickus had decided that Stephan would be climbing the mast.
Our plans were almost derailed when Brian ZS6YZ was requested to represent the IARU at the ATU African Telecoms / ICT Commemorative Workshop in Maputo from 5 to 7 December. Rickus ZS4A again had a plan and after consulting with Carl ZS6CBQ sprung the plan on me. He needed to deliver stuff to family in Heidelberg on 21 November and then collect Stephan from the airport. We arranged that I meet him in Heidelberg with all the beacon hardware and he would then take it back to Bethlehem along with Stephan.
The installation team, all from Bethlehem were up early on Saturday 7 December at the high site in Bethlehem. Carl ZS6CBQ also joined them and they started just after 7:00 to get the brackets mounted on the mast, hoisting the antennas into position and by 10:30 the installation of the antennas on the mast along with the splitter cable and the coax to the repeater hut was complete.
Bethlehem Installation Team
Antennas
Antennas mounted
The beacon was powered up and glowed in the dim light of the repeater hut. No, it was not the valves glowing in the dark or the radio glowing because of excessive heat generated. It was the blue LED’s on the fans.Bright enough to cause you to want to reach for the sunglasses!
Beacon
The CW message was sent into the troposphere and shortly signal reports started appearing on the 46 Long Distance VHF/UHF WhatsApp Group.
ZS0BET was on the air and being well received in Gauteng. It was even received off the back of the antennas in Bloemfontein and Kimberley, although much weaker.
Well done to all involved who put in the time and effort to get this beacon on the air. The VHF Working Group, Carl ZS6CBQ, Rickus ZS4A, Cor ZS6CR, Hans ZS6AKV, Nico ZS6QL, Dick ZS6BUN, Brian ZS6YZ, Nigel ZS6RN and Willem ZS6WIM. Koos ZS6KSG who built the beacon box, Danie ZR6AGB who helped with the testing and the guys that Rickus lined up in Bethlehem to assist with the installation Charl ZS4ATZ, Wallie ZS4LD, Daniel, ZS4DA and lastly the climber of the mast who did all the dangerous work, Stephan ZS4SDL.
This was truly a team effort. Job well done!
Early in the new year the VHF Working Group will regroup and get the ball rolling on finding a suitable site in the Northern Karoo for the next beacon.
Please send your news snippets and information about activities on VHF and Above to vhfnews@sarl.org.za.
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