RaDAR – Testing for NVIS

I had built a QRP Labs U3S and run it on 40m and 20m. My main interest is in NVIS communications (Near Vertical Incindence Skywave). Many years back I visited a facility in Hermanus, South Africa where they test for various HF propagation conditions. The term Ionosonde comes to mind.

Well I made my own system that seems to work very well using WSPR as the source on the U3S and WSJT-X together with a SDR-IQ as the receiver. Allow me to present some further detail.

In KG34ac (Lichtenburg) I run the U3S using a 40m / 20m trap inverted vee. I built the simple traps myself on tiny pieces of PCB using a 30 turn winding on a red toroid with a parallel 47 pF capacitor. On 40m the U3S puts out 200 mW and on 20m, 50 mW approximately. The WSPR sequence is repeated every six minutes.

In KG34ac (Molopo), 29 km away as the crow flies I run WSJT-X in WSPR mode talking indirectly via virtual audio (Software) and Spectravue (RF Space’s SDR software) to the SDR-IQ SDR HF receiver usually used as a CW monitor for the RBN (Reverse Beacon Network) when appropriate..

These two options allow some pretty interesting observations. I use WSPRD at http://wsprd.vk7jj.com/ to accumulate the data and create an appropriate graph from that data using LIBRE Calc (Freeware office software).

The results coincide with real world propagation opportunities for NVIS communications. I drew this graph from recent data.

Now that’s using WSPR for a purpose! The SNR values are usually well into negative values for example -27 or nothing at all. Anything above the zero line is a very good indicator that suitable conditions exist.

73 de Eddie ZS6BNE

RaDAR – The QSO Today virtual expo 2021

In South Africa we are experiencing a lot of load shedding, two and a half hours at a time sometimes twice a day! It so happened too when I was supposed to join in via Airmeet on my pre submitted RaDAR presentation hosted by QSO Today’s virtual expo.

In between these power failures I really battled to navigate the website and once I got reasonably familiar with the layout I was unable to get my video and microphone to work so it wouldn’t have helped to even implement emergency power and get online.

Ed DD5LP was the host for the session and he sent me a mail later that he was able to successfully broadcast the presentation. In effect, Ed saved the day. Thank you Ed! Ed sent me some Q&A’s which I will try to reply to here on my blog and can be distributed easily.

Ralph KR6AI from what I’ve seen it depends on the environment and the target area. I’ve seen hams’s using Alex loops, verticals near salt water and end feds. I prefer end feds as it is easy to deploy and here in South Africa we are many hops away from DX so I usually concentrate on NVIS communications.

Theodore KD2TGO the official RaDAR website is one I maintain and can be accessed at http://www.radarops.co.za however RaDAR is an experience and many use social media platforms to share experiences and many videos are available on You Tube. The more we become RaDAR active internationally the more we can see the experience of others and also share our own experiences in the same way.

Usually low power equipment like a KX2 / KX3 / FT-817 and even the new QRP Labs QCX Mini. Antennas are usually made of wire. For satellite communications I use a TH-D7A(g) which has a duplex facility. Antennas for satellite communications can be home brewed very easily or you can use the popular makes like those from Arrow antennas.

Jim N7RCS I would love to write an article. I would need some contact information and guidelines.

Dennis KD9KMK I did one challenge in a canoe. It was quite challenging but one can row to a point, climb out and deploy your station after moving a kilometer. Unfortunately our river dried up for reasons beyond our control so my canoe is no longer used. It was a fun exercise though!

Bruce W1EJC the band of choice would be the one giving the best propagation at the time. I usually spend my four hours on 40m and occasionally do satellite deployments too.

If I had my way I’d do all my contacts on CW. Here in South Africa we have only a few CW operators and around ten regulars. Much of the action is on SSB which limits the usability of the radios like the QCX mini which is CW only. Our CW group is growing much through the driving force from Mike ZS6MSW so hopefully in the future we may see a CW only four hour challenge. That would be awesome!

Much work went into the QSO Today virtual expo, the many presenters and the organisers must have had a heavy weight on their shoulders this past weekend. The technology I think was really awesome but complicated. I think there were many teething problems but let’s continue to support Eric 4Z1UG in ironing out the problems that the next expo be more familiar. I felt lost at times and I come from an IT background!

Have fun and spread the word of RaDAR.

Kind regards and 73 de

Eddie ZS6BNE

RaDAR – WSPR our propagation tool

I had built the QRP Labs U3S WSPR transmitter and expanded it for two bands namely 40m and 20m. My interest is 40m as most of my RaDAR operaions take place locally although during the challenges it’s always good to cross the oceans and access other continents and make contact with other RaDAR operators around the world.

For quite some time (A few weeks) I have been WSPR’ing from my RaDAR playground in KG34ac but I started to get irritated by the slight QRM I was experiencing on my CCTV cameras which I use as “The poor man’s trail camera”. Seeing my grandson was returning to school after almost a year attending on line schooling due to Covid-19 my wife and Eduan had to go back to town in Lichtenburg and only join me on weekends again. I had to do a few chores there yesterday and took the U3S into town and set it up there. I had built a trap dipole for the purpose and got it up at about five meters above ground in an inverted vee format. The antenna was fed with a length of RG215, better than it was here at home.

I had to update my 6 character TX grid to KG33bu on the WSPR database after I found it was only registering 4 characters on the WSPR database. I had conflicts with duplicate call signs in different locations so the RX side I renamed to ZS6BNE/p which is what it is actually. I use a RF Space SDR-IQ SDR running on its software typically Spectravue. I use a virtual audio cable (Software) to channel the audio to WSJT-X running in WSPR mode. Here too I have an inverted vee on 40m for reception. My main concern obviously is 40m.

This opened up some interesting facilities. ZS6BNE TX in KG33bu and around 30 km away as the crow flies the ZS6BNE/p RX in KG34ac. This is my own NVIS alert / testing facility and has already shown some interesting results!

As suggested by a friend on our local WSPR WhatsApp group I use http://wsprd.vk7jj.com/ to do queries on the WSPR data. From this data I intend pulling it into Libre-Calc and drawing graphs from the results. Here you can clearly see a NVIS opening and to prove it I made contact with Andy ZS6ADY who is usually skip to me!

I’m looking forward to those graphs and seeing the interesting results!

73 de Eddie ZS6BNE