23cm Aircraft Scatter - Beaming at aircraft rather than along a direct path and the benefits of Q65.

The basic concept of aircraft scatter (AS) is similar to that of radar. However, in the case of aircraft scatter we are generally relying on signals being scattered forwards to a distant receiving station, rather than back towards the originating station.

This posting is about a series of tests carried out to establish the best way of targeting the distant stations using narrow beamwidth 23cm antennas and which data (or other) mode to use for this purpose. It is an expanded and updated version of my article which appeared in the GMDX group's Digest (gmdx.org.uk).

As usual, click on images to enlarge them if necessary. 

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In practice radio amateurs can use AS on the VHF and UHF bands to achieve QSOs up to a distance of about 600km. The exact distance will depend on the frequency, the height of the aircraft and the curvature of the Earth. This range can be exceeded by tropo ducts, but these are fairly rare. In the absence of a duct aircraft scatter is the most reliable way of reaching stations in the 250-600km range. The larger (or “heavier”) the aircraft, the better chance you have.

I recently started a series of trials on 1296MHz with Gordon, GM4OAS. Our stations are broadly similar, with Gordon running 250W and two 36 element yagis. I have 150W and one 36 element yagi. The path is 257km in length which might make us think that a tropo contact in normal flat conditions would be possible, but the terrain here means this would not be easy. The path crosses close to Ben Nevis and many other Highland peaks in the Munro Tops category. It starts close to sea level at each end and reaches over 750m several times on the way.

The mountainous path from GM4FVM to GM4OAS makes UHF tropo contacts difficult (AirScout) 

Despite many attempts we have failed to make a tropo contact between us and we are certain that any signals between us rely on aircraft scatter. 

AirScout

Starting out on using AS the immediate problem is not knowing where the aircraft are, and thus not knowing when to call in the hope that an aircraft is passing between you and the station you wish to work. To solve this dilemma there are several sites on the internet offering maps of overflying aircraft using their transmissions on the 1090MHz band to capture the height, direction and speed of the aircraft plus a host of other details.

Many amateurs use AirScout software by DL2ALF. AirScout uses reception of the 1090MHz transmissions to produce a map showing the aircraft. It integrates this with the location details of the station which you wish to work. Thus, when you enter the station you wish to contact it adjusts continuously to present a diagram of the path involved, the terrain, and any aircraft along the path which are at the desired height. (See reference [1] for a comprehensive description of the technique and the software). I have been using Airscout for several years.

After several AS contacts, initially using a single 36el yagi at each end, Gordon achieved dramatically improved results by deviating his yagi direction away from the strict direct path between us and towards specific aircraft instead. This involved using an ability AirScout has to directly communicate with rotator control software.

Up to this point I had used AirScout in standalone mode, setting the beam direction to the distant station manually. It seemed to me to be impossible to follow a fast-moving aircraft with the narrow beamwidth of a microwave yagi. I was not aware that AirScout has the capacity to communicate with the antenna control software in my computer to allow tracking individual planes - planes which could potentially be some distance away from the direct path.

Aircraft Tracking
Tracking as a concept will be familiar to many VHF+ enthusiasts. Many of us use a similar set-up to automatically follow the Moon across the sky while attempting “moonbounce” QSOs. However, the idea of tracking individual aircraft was new to me. Obviously, tracking the plane makes more sense than pointing the antenna direct at the distant station. It is the plane which reflects the signal, and it should be the obvious target. However, planes travel more quickly across the sky than the Moon does! Gordon explained to me the steps I would need to take to set up aircraft tracking and after a few false starts I got it working. I had not known that I had to upgrade PST Rotator (Software for Antenna Rotators) to the VHF/UHF version first. See reference [2].

My rotator for the 23cm antenna is a SPID RAU. The control unit for this rotator either has a USB or a parallel socket (in my case, parallel) to allow connection to a computer. The software I use in the computer to drive the SPID is “PST Rotator”. When tracking is engaged PST Rotator looks for a dump file in AirScout which contains the latest instructions from AirScout to point in a particular direction. AirScout knows which plane to follow because the user identifies it by clicking on targets from amongst the options presented. 

AirScout turns the aircraft image red if it appears to be likely to cross the direct path – otherwise they are grey. In the past I only considered red targets, and only when they were near the direct path (Airscout also indicates when they are very close to the path). Once we started targeting specific aircraft we mostly selected images which are grey and not very close to the path, the opposite to what we did before.

Without having to consider how all this works via all the different interactions etc, I can now click on the image of a plane on the map, and the software continues to find out where it is and points the antenna towards it as it moves relative to me. Just to assure me that AirScout is keeping everything under control, it continuously shows a compass bearing towards the plane which it is following, and I can see the bearing changing regularly on the rotator controller too. I can also hear the SPID turning through the shack wall (!). Eventually the plane goes out of range and the tracking stops.

AirScout showing an aircraft North of the direct path to GM4OAS which was suitable with tracking. Note that none of the planes are near enough to the direct path to be coloured red and they would not have been considered candidates without tracking.

The result of changing from beaming along the direct path to tracking the aircraft was remarkable. QSOs were longer and signals stronger. We had three or four contacts for each plane, allowing repeated QSOs to check the outcome. 

It has to be said that this path to GM4OAS possibly favours this approach. On long paths, perhaps over 400km, the difference between the beam heading for a usable plane and the direct path will be smaller. For long paths planes in some directions would be below the radio horizon if far off the direct path.

While it was not easy to calculate the exact distance away from the direct path we were able to use, we estimated it as in the range of 25 to 40km. This brought many more planes into consideration. Once we were both using tracking, we had a series of near-continuous contacts over a period of two hours, selecting likely planes as they arrived on the screen.

Somewhat chaotic screenshot taken during the tests. Two aircraft following each other off path provided time for repeated QSOs. The two traces can be seen on the screen.

Why use tracking? 

It would of course be possible to estimate the position of the aircraft and simply point the beam manually in that direction. The plane could then be followed by dead reckoning using the map and constantly updating the rotator via the controller. This would require a lot of guesswork and antenna repositioning. As a halfway house, the on-screen compass bearing could be used to follow the plane whilst controlling the rotator by hand. However, as AirScout could do the whole thing automatically that seemed like the best way to proceed given that aircraft scatter contacts require full concentration on their own.

Compass shown on AirScout while tracking an aircraft

We used tracking not just because it takes all the hard work out of keeping the beam pointed at the aircraft (but it does that nicely). It also finds the correct angle far more accurately than would be possible chasing the plane manually. I do not yet have antenna elevation, but it would set that automatically too. And finally it solves the biggest problem - it can keep pace with the fast moving planes.

Which mode to use? 

For the tests we started by using FT8, which failed. We then switched to Q65 version 15B. Q65 is particularly good at handling Doppler shift created by the motion of the aircraft. A 15 second tx period is short enough to complete a QSO during brief flyovers. We did not just use Q65 because I like it (though I do like it). We then tested Q65 against FT8, FT4 and CW, using aircraft tracking. 

We became familiar with the plane passes which worked with Q65. Over a number of these passes FT8 was a failure.

Typical failure to make contact using FT8, with zero decodes reported at either end of the path. Note the exaggerated Doppler shift common to all these tests.

FT8 failed for several reasons. It is less sensitive than Q65 - its coding makes it less suitable for scatter use as it cannot deal with what Doppler there is - and its longer 30 second periods allows for twice as much Doppler shift in the first place. 

We then tried a comparison with FT4, hoping that its shorter period might help. However, FT4 is even less sensitive that FT8, so the benefits of the shorter period were largely lost. Still, over a period FT4 give roughly one decode for every five decodes using Q65 on comparable plane passes. 

This is not an ideal way to rank these three modes as it did not directly compare them at the same time but instead measured decodes per plane pass. However, with a fairly large sample size I think it gave a representative result. Broadly we found the FT8 did not work at all whilst FT4 worked to some extent but not as well as 15 second Q65. These results were what you would expect given that Q65 is designed for scatter propagation and FT8 and FT4 are not. 

As an experiment we also exchanged callsigns on CW.  Later we tried to complete a QSO on CW while using tracking and this was successful. The signals were quite strong so this should succeed but the effect of Doppler was rather off-putting. At some stages the Doppler shift meant that the CW station fell outside the receiver's CW filter as the QSO progressed. 

We did not try SSB, which is often used for AS contacts during contests. Whilst tracking increased the duration and strength of reception, it also increased the potential for Doppler shift. Whether this would cause problems for SSB contacts is something which needs to be investigated. It may be that at 432MHz, where the shift would be smaller, there could be useful gains to be had.

Doppler shifts of 400 to 700hz over four minutes were common and this is difficult to deal with in most modes except Q65 and similar protocols specifically designed for the purpose.

Summary
Tracking the aircraft rather than beaming at the distant station produced improved results in the tests. This can be done automatically, which was something I had not considered. It is a method which I will be keen to try more often in future. Provided AirScout can access a reliable feed of 1090MHz plane data (something which it sometimes fails to do) this approach seems to have merit.

Q65 seems to offer benefits over other data modes and CW.

Thanks to Gordon GM4OAS for guidance and encouragement with this experiment.

References: 
[1] http://airscout.eu/index.php. The latest issue of the AirScout Aircraft Scatter Prediction Manual may be downloaded from here: http://airscout.eu/downloads/AirScout_V1_4_0_0_EN.pdf
[2] Information about PstRotator – Software for Antenna Rotators may be found here: https://www.qsl.net/yo3dmu/index_Page346.htm 

Ionoscatter 2026

Ionoscatter ("ionospheric scatter") is forward scatter in the ionosphere. I often work stations on 2m from 800km out to about 1600km at around this time of year, but I reckon that ionoscatter has potential for use during much longer periods.

In the past ionoscatter was only thought useful for very high powered stations. Now with the benefit (?) of FT8 I find it useful at moderate power (200 to 400W) with an equally moderate antenna (9 elements) during June and July. With a more suitable data mode I suspect it would be useful for longer periods during the year.

Right, on now to this year's results so far:- 

144MHz Ionoscatter contacts at GM4FVM on 2 and 4 July 2026

Click to enlarge image etc. 

OK, so first issue:- this looks like the time of year and direction you might be working Sporadic E, so how can you be certain this is not Es?

Well, Ionoscatter (should we call it Is to distinguish it from Es?) is generally much weaker. Also, unlike Es it hangs around for ages and can last hours on an individual station. And thirdly it tends to occur only at this time of year (using FT8). So, in 2023 I heard it four times between 30 June and 12 July, in 2024 only once on 23 June, in 2025 not at all, and so far on two days in 2026, 2 and 4 July. Generally the times were between about 10:00 and about 13:00 but one as late as 14:39.

Left: a tropo signal (MM0CEZ), right ionoscatter (SM0LQB)

Ionoscater leaves a unique trace on the FT8 waterfall. It is often broken and patchy but stays at the same strength. Often you can see meteor scatter bursts which usually prevent the transmission from decoding. Using FT8 it can take a while to get the QSO finished. The key point is that although it is weak, the signal can been seen for long periods at fairly steady strength. The ultimate limit is FT8's ability to decode it because FT8 is not a very good mode for very weak signal work.

Second issue. You may ask what is the point of looking for this form of propagation when it is weak and only usable for a short time of year. Well, it seems to me that if we were unleashed from the limitations of FT8 it would allow decodes over long distances for much longer periods of the year. 

The mode I would suggest which I fancy would work better would be Q65. Much work was done by G4CDN and others using JT65 and QRA64, the modes which were available to them at the time (see  https://ei7gl.blogspot.com/search/label/Ionoscatter and please don't blame me if this link stops working - look it up instead). JT65 certainly works, but surely Q65 is much better suited to this type of work.

Ionoscatter is in fact working at the higher end of its frequency range at 144MHz. It is suggested that it works best at 35MHz and it should therefore be a good target for 50 and 70MHz experiments. And yet I rarely see European stations trying this. If I look at DXMaps I often see US and Canadian stations working to these sorts of distances using Q65, but I do not see that on this side of the Atlantic. Anyone interested? 

Some of you used to read my old blog, where I often lamented the use of FT8 on VHF/UHF. I feel sure that Q65 is far better suited to these frequencies. Well here I go again and I am not finished today. If you read the WSJT-X Users Guide you will see the uses Q65 can be put to. It even shows a Q65 Ionoscatter image. I'll print it below here because I suspect that very few amateurs ever read the guide, but instead use WSJT-X without really knowing what they are doing....

So for now I will continue to look for Ionoscatter on 2m for a few weeks each summer, mostly in the mornings. I know that it has far more potential, but if everybody insists on using FT8 then that is the only few weeks I can use it.

Any Q65 skeds from stations in the 800km to 1600km range welcome. 

73 Jim

 

 Below: From WSJT:X users guide (link to QSJT-X site is in the side bar of this blog)

12.4. Q65

Q65 is designed for fast-fading signals: EME, tropospheric scatter, rain scatter, ionospheric scatter, trans-equatorial propagation (TEP), and the like. The following screen shot shows the Wide Graph and decoded text windows after processing a Q65-60A sequence received via EME on 6 meters, by W7GJ Transmissions are decoded from N0TB, N8JX, W1VD, and VE1JF, all by the EME path.

The Q65 decoder takes advantage of a priori (AP) information such as the encoded forms of one’s own callsign and the message word CQ. In normal usage, as a QSO progresses AP information increases to include the callsign of the station being worked and perhaps his/her 4-digit grid locator. The decoder takes advantage of whatever AP information is currently available.

Here’s a similar screen shot for a 6 m ionospheric scatter signal over the 1155 km path from K9AN to K1JT, using submode Q65-30A. The received signal was barely audible most of the time.

Mostly more Sporadic E

It is not easy to describe recent Sporadic E.

VHF/UHF contacts at GM4FVM, 23 to 30 June 2026

Click to enlarge the images if necessary. 

You see, Sporadic is what I am used to. Sporadic. Like this:-

It is not there - it is there - it is not there.

So it has distinct phases of happening and then not happening. You usually have time to recover and work out what has been going on.

In midsummer on 50MHz there is often Es to be noted on most days, but not always. This is manageable without a lot of frantic action. The length of opening declines and the panic rises with the frequency. On 70MHz it has occasional events lasting a hour or less, and on 144MHz sudden opening lasting maybe 5 minutes.

Because I am interested in better understanding Sporadic E I watch it across all three bands, and operate on the highest band possible. I go to the highest band I can but I do slip up and down when I see something interesting lower down.

This all works nicely because you never get long openings on the the higher bands, 4m and 2m. And you have more time on 6m for consideration. That is my plan of operation.

My plan completely fell apart recently when there were long openings on the higher bands.

For example, on 21 June 2026 there was an opening on 144MHz to Italy. However, this did not last two minutes as I might have expected, but 35 minutes. I worked 21 stations on 2m during those 35 minutes, with more attempts being made but failing. In the usual 2m Es style the opening moved around the country with stations coming and and it going at a frantic pace, but it appeared to keep going for a long time.

A 35 minute opening for Es on 2m is very very unusual. Maybe it happens that we have a longish opening, but it moves between countries, has gaps, and does not last 35 minutes. In my experience this was remarkable.

Since then I tried to analyse what was happening by relating the map and the timings. It seems to me that there were three distinct phases to that event. First an opening down the Adriatic Coast from Padua in the north as far as Puglia in the extreme south. Then there was an opening around Rome. Finally there was a third event starting in the north around Verona and spreading down the centre eventually ending around Naples. There was a final twist to one station near Matera in the south. 

It is hard to tell, but this looked like a succession of three separate openings, each of which would have been more like what we normally see, plus a single station at the end. Looked at that way this was in fact three large openings, rather than one huge opening.

Maybe. It is easy to look for patterns in things. But it certainly was unusual.

Just as 144MHz was going for longer openings, 6m was going the opposite way. It was open routinely into Europe and no DX was to be seen. Then suddenly I missed XE2X on 17 June, also missed JA5AUC on 21st, worked BD7IS and BD0DLA separately on 22nd, HI3T on 28th, plus CO8LY, VO1HP and FP/KV1J all separately on 29th. These were not part of long openings, but random single QSOs separated by periods of no DX.

So, 2m Es was behaving like 6m Es and 6m Es was behaving like 2m Es.

Over a week I completed 197 QSOs to 42 countries, 12 on 6m, 53 on 4m, 115 on 2m and 17 on 70cm. There was also a moderate tropo opening from 23 to 25 June, but this paled into insignificance when the Es started. During tropo on 2m you can bank on fairly stable conditions and you have the time to work your stations but with Es you have only minutes. You have hop around, jumping on any contact that looks likely to last the 60 seconds or so you will need. The standout aspect of these conditions was that there were long periods of continuous operation which is very unusual on 2m Es.

It was after 25 June that things went really dooh-lally. There were a series of openings on 70MHz and 144MHz the like of which I have never seen before. It was like being in a continuous contest. 

On 2m: 25 June I made 20 QSOs, on 26 June 42, on 27 June I was away, and on 28 June 23 more. I worked 20 DXCC in 46 squares in 4 days on 2m. The figure for the whole of 2025 was 25. 

Austria 3, Belarus 5, Bosnia-Herzegovina 2, Croatia 6, Denmark 4, Germany 17, Hungary 6, Ireland 1, Italy 15, Kaliningrad 2, Lithuania 6, Netherlands 4, Poland 2, Romania 1, Scotland 1, Serbia 1, Slovakia 4, Slovenia 2, Sweden 2, Switzerland 1. 

Best DX was to IZ7EZN at 2285km, with 24 other contacts over 1600km. 

144MHz contacts at GM4FVM 24 to 28 June 2026

On 4m, 40 QSOs, 6 on 25 June, 16 on 26 June, none on 27 June and 18 on 28 June reaching 35 squares in 20 DXCC. These 40 QSOs were made despite the fact that France, Germany and Italy are not currently on the band.

Austria 2, Belgium 1, Ceuta & Melilla 1, Czechia 1, England 3, Estonia 1, Finland 3, Greece 6, Hungary 2, Latvia 1, Lebanon 1, Netherlands 1, Norway 5, Poland 1, Portugal 2, Serbia 1, Slovakia 1, Spain 3, Sweden 3, Swtizerland 1.

Best DX OD5ET 3766km, after that  six stations in Greece from 2458km to 2636km and then EA9IB at 2289km. 

70MHz contacts at GM4FVM 24 to 28 June 2026

I said that the start this is hard to describe. Do I think of it in terms of distance worked, number of stations or countries, or of duration of the opening, Do I try to analyse the events? Well, apart from the Italy opening I have not had time to analyse anything. It has just been a blur.

This has been outstanding. As I say, I have never experienced anything like it. 

I hope others were able to join in too. 

73 Jim

GM4FVM 

Stuck masts and falling screwdrivers

I thought my greatest problems at the moment were the holes made in the drive by a marauding hedgehog. I even have pictures of him/her (can there be two of them?) wrecking the place thanks to an infra-red trail camera. They are entitled to be here, but can they not use the drive to pass along rather than dig it up?

No, things got worse when my main mast suddenly started to give problems. The main mast is a CUG 12m three part square section mast, with my 6m, 4m, 2m and 70cm antennas on top. I will no doubt give more details on the antennas later, but for now it is the mast itself that took all my attention. The mast is raised and lowered using a lead-acid battery powered winch. I recently replaced the winch and the wiring and then fixed up the original winch as a spare.

First problem was that it started to go up and down slowly. Having replaced the winch I thought that it was unlikely to be the problem. Then it would only go up twice before the battery needed to be recharged while before it would go up and down eight or ten times between charges. Although the battery appeared flat and it would not raise the mast, the smart charger declared that it was 100% charged. Most odd.

Then it blew a 25 amp fuse. I had increased the fuse from 20 amps to 25 amps during the re-wiring because the previous one had got scorched but it had not blown. It seemed unlikely to me that the 25 amp fuse would blow under normal circumstances.

GM4FVM fault finding with his mast and almost new winch (photo Mrs FVM)

Clearly something was adding a heavy load to the winch. I would have to investigate further. 

I then recalled an occasion 10 days before when I had tried to lower the mast on a windy evening. The middle section of the mast had jammed about 30cm before the bottom. This was due to the wind pushing the mast aside in the bottom tube and it then caught on a piece of poor galvanising and stuck. There are a couple of bits of poor galvanising on the mast and this has caused trouble before. Perhaps this was the cause of the current problem.

As in all good scary TV police reality shows (isn't "24 Hours in Police Custody" the best of these??) I had to go and seek CCTV images to find the culprit. Luckily the Anti-Hedgehog Trail Camera (AHTC) recorded the whole event on 4 June 2026 starting at 21:25.34 when the temperature was 11C (flaming June weather in IO85) and the sound track proved it was windy. Ah ha! Evidence. PC Dixon has found the culprit - me. Well, actually a combination of the construction of the mast and the wind - and me.

I had trouble lowering the mast fully that night ten days before. When I tried to lower it the middle section stuck and the cable lowering the upper section (which confusingly is on the middle section) fell slack. Now I was worried at the time that when the slack middle section cable eventually tightened up it would not fall back fully on the pulley, so I reckoned I had better get the thing down properly.

By repeatedly raising the mast a small amount, about 50cm in total, and lowering it again I kept returning to the point at which it was sticking on the way down. I only did small movements to prevent the slack cable from failing to seat back on the pulley. Eventually a slight drop in the wind allowed the middle section to drop past the sticking point and it was fully down. 

What I had not noticed in the dark evening was that the very thing I had been trying to avoid had happened. When the middle section cable had tightened up again it had fallen down the side of the pulley. This meant that the cable on the middle section was turning round directly into the inside of the mast rather than going smoothly over the pulley. This increased the resistance, added strain on the winch and was potentially going to lead to the cable wearing and breaking.

It was hard to see this from the ground, but up close the problem was obvious:-

Cable down side of pulley

The danger of this wearing down strands of the cable to the point where it snapped was sufficient to get me to fix this right away. I happen to know that I started to fix it on 15 June 2026 at 09:32:10 and when the temperature was 15C. This is from intelligence gathered by the hedgehog detection system.

I knew that all I had to do was to generate some slack in the cable and then pull it over the pulley. To do this all that was needed was to push the middle section of mast into the bottom section while holding the top section fixed to the middle. Impossible in my current ancient weedy state as I do not have the strength left to push the mast in while it is lying on its side with rotator and antennas on top. Simple, just fix the upper section steady and tilt the mast vertical when it will fall back together under gravity and the cable will go slack. That is how it went slack in the first place. Well, maybe.

I had got confused because it was the upper section that I needed to fix in place whereas I tried to fix the middle section. I did this by wedging two large heavy screwdrivers into the gap between the sections and turning the mast vertical. So I wedged the middle section rather than the top one, but it worked and at least I had proof of method for getting them in the right place next time.

Two old heavy screwdrivers in the wrong place, but the idea works

While I had the mast vertical I momentarily pressed the "In" button on the winch control rocker switch rather than the "out" one. It only moved a fraction, but that was enough to release both screwdrivers from a height. They clattered down the back of the mast, hitting the mast brackets before scattering. One has never been seen since. I have no idea where it went. What could I do, apart from sending Mrs FVM to look for it and she has not reported back since. It a big thing but it is lost. This just shows that a hard hat is needed for working on antennas as a large screwdriver falling from a height could do a lot of damage to the head.

Luckily it turned out that one screwdriver was enough to hold the top section up and everything worked out fine. The cable is now happily seated on the pulley and everything runs smoothly. 

Next snag is that the mast jammed briefly at the same point last night during windy conditions. This time the cable did not lift, but it could have. I must get round to filing down the uneven galvanisation at the point where it jams.

Things to note:-

Beware slack cables on masts 

Beware falling screwdrivers

Beware large screwdrivers disappearing into thin air

Beware hedgehogs vandalising your drive.

Hedgehog attacking GM4FVM drive around 00:20 local time

In fact, just be careful.

73 Jim

GM4FVM 

 

 

Mostly Sporadic E

Time for a short summary of the past two weeks of operating. This has been Sporadic-E on 6m, 4m and 2m, and flat-band tropo on 70cm and 23cm.

 

Contacts at GM4FVM 31 May to 13 June 2026.

There was an all-time new DXCC in the shape of St Lucia on 6m. This was an all-time first for me on any band.

Contacts at GM4FVM 31 May to 13 June 2026.

Over all, not bad for two weeks  I would say, but Africa and Asia sadly under represented.

Vraiment pas mal. 

73 Jim

GM4FVM.

What is it with 23cm?

What is it with 23cm?

I was reading a fellow GM's blog today and I saw that he said that working UHF was "highly addictive". 

Today I have been working my three-band trick. Six meters open, four meters stuffed with OIRT broadcast stations in Belarus and Ukraine, and me on 2m working OE and 9A. Surely that would be fun enough for anybody?

That is good but it is not enough for me. Clearly I need THAT --- and I need MORE.

When I started out on my ham career microwave bands involved dark arts. Mysterious waveguides, unaffordable coax the size of drain pipes, and wartime Klystron valves. Or the other route involved triplers such as those made by Microwave Modules. Some folk started at 144MHz, tripled to 432 and then tripled again to 1296, resulting in an FM signal as wide as a barn door. And this was a barn door that drifted up the band. To hear this stuff you used a receive converter.

I never got near microwaves then. Even for 144MHz I started off using a valve receive converter down to 28MHz and then into a deaf AR88. My transmitter started with an 8MHz crystal and multiplied up to 144MHz, so going up six more times seemed like a crazy idea. Or too much like hard work.

Then, decades later, after the passage of  much RF, I was left a brand new Icom IC-9700 by David GM4JJJ. When I mentioned to Neil, G4DBN, that I had an IC-9700 but I only used it on 2m, he sent me a Wimo 28 element yagi. So there I was with rig and antenna. I reused some old coax and I was on the air on 23cm on 1 September 2019.

My limited knowledge, formed over 40 years before, was that this was a very difficult band to manage. This stuck with me for a while. Plus I had the idea that this little antenna would surely only send out dibbly-dobblers and I would never be heard anywhere. I reckoned the results would be pitiful. You can judge for yourself how wrong I was.

1296MHz contacts at GM4FVM since 1 September 2019

Click to enlarge images, blah, blah, etc, etc. 

OK, it has taken seven years to do all this but I have had 247 QSOs and worked 14 DXCC during that time. True, 32 of those QSOs have been to JO46 square in Denmark. The fact that my most worked square is in OZ is really due to geography. My antenna is basically pointing straight across the sea at Denmark, whereas towards the rest of Scotland it points at the Lammermuir Hills followed by the Pentland Hills and then the Highlands. Generally working Denmark is reasonably simple if there is a tropo lift across the North Sea, and there often is. This high number of contacts is despite JO46 being at least 630km away and beyond aircraft scatter range.

During a tropo opening 23cm often becomes my favourite place. I can forget all that stuff I believed in all those years ago. My ODX for a tropo lift was to LY2WR, 1719km away in KO02. That was about 1500km further away than the best DX I could imagine on this band before I started.

Now of course my station has altered slightly over time. I found that the IC-9700 drifted on 23cm so I added a Leo Bodnar GPS frequency standard. I upped the power using W6QPL amplifiers, first to 50W and then (thanks to Sid, G8SFA) to 150W. At various stages I have been using a 36 element yagi, and at other times reverted to the original 28 element. Although there is supposed to be a 2dB difference between them it seems to matter little. I am still using 19m of Hyperflex coax which manages to lose half the signals thanks to having 2.9dB loss at 1296MHz. I now have an SHF-Electronik MVV-1296 masthead preamp which has a noise factor of 1.5dB.

My station is modest. I could make it better. To me that is worth thinking about but not the point. I do not run a kilowatt or have superb antennas on any band. I work on five bands and I cannot have a superstation on all of them. Hopefully over time it will get gradually better, but my initial effort to get going has proved that 1296 is indeed worth the effort.

How can I illustrate where I can work to on this band? What about listing my five most recent QSOs (in reverse order of course, this is my blog after all)?

1) 30/5/26 G4ALG/P. IO81. I did not get Steve's exact location but this was over 400km and not an easy path over the Cheviot Hills and then the Pennines. It was his best DX on 23cm to date. Unusually for me this was a CW QSO. It was assisted by aircraft scatter. I like helping someone to their best DX, even if he has to try to understand my awful CW. [EDIT:- It was 445km to IO81RU - Steve returned a QSL card]

2)  23/5/26 GM4OAS IO75 258km. Difficult path. Thanks to Gordon being on the far side of the Highlands, this had to be entirely by aircraft scatter. Gordon suggested starting on FT8 but the Doppler was too high so we switched to Q65. You can see the steeply sloped trace on the Q65 waterfall showing the Doppler shift, which Q65 coped with well. We actually worked twice with the same plane.

QSO with GM4OAS on 23 May 2026.

3) 15/5/26 NC1I FN32 5133km. This was my first moonbounce QSO on 23cm. Frank was amazed when he heard how much power I had at the antenna thanks to my lossy coax. Of course he has a superstation with a big dish, but he still needs people to work. It was Frank who started me off on 70cm EME too. Indeed Frank started me off in all EME. I was using my 36 element yagi with no elevation.

QSO with NC1I on 15 May 2026

4) 1/5/26 LA3EQ IO28 563km. This is actually also the 5th QSO. I heard LA3EQ over a 48 hour period during a tropo lift. I worked him eight times on three bands. Although we only worked twice on 23cm, the report was +16dB and at one point he was +23. Even I cannot work someone repeatedly over 48 hours.

Above is a slice of my 23cm QSOs from my logbook. LA3EQ is a classic tropo lift/duct. This enhanced tropo propagation stayed up across the North sea for two days and at times allowed incredibly strong signals. 23cm can have superb tropo ducts. NC1I shows that you don't need a superstation or even elevation to work somebody on 23cm EME (provided they DO have a superstation at their end). The tell-tale trace off to the right on the first map above is that QSO. GM4OAS shows how aircraft scatter can cover the most tricky terrain. And G4ALG/P showed how with him running 20W we could add to a weak "dead band" path by using aircraft scatter.

FT8 might work for tropo, but Q65 is needed for aircraft scatter or EME. CW, as we are often told, is best in every situation ...

I have tried to show how I have become fascinated by 23cm. I wrongly believed that it was difficult, not taking into account how much technology has changed over my ham career. [That is a long career Jim]. Are other hams also put off by such mistaken notions from the past? How many IC-9700s are in use, maybe only on 2m as mine used to be, and are wasting their capacity to work 23cm? Could others be amazed by 48 hour tropo ducts, mind boggling aircraft scatter and EME on a shoestring? I bet they could.

What should I do next? Be content with my modest equipment? Go for high-spec coax,or a dish, or elevation, or more power, or a better preamp, or add higher microwave bands? Or all of these? I don't know. But I am thinking about it. I sometimes wonder if the best amateur radio set-ups are the ones we plan in our heads. The 23cm one I am planning is great - in my head.

23cm is just one of the five bands I use. It can be silent for days (/weeks) on end. When it opens it can be superb. 

I love the 258km QSO with Gordon just as much as the 5133km one with Frank. 

Everything on 23cm is DX compared with what I expected.

"Highly addictive" the man said. 

Do you think that I am hooked?

They tried to send me to rehab, and I said CQ, CQ, CQ. 

73 Jim

GM4FVM 

2m sporadic E

It is nice when a plan works.

On 24 May 2026 there was a large opening on 70MHz. When I say large I mean over a wide geographical area (there aren't enough active stations on 4m to make it really large). Large enough for me to work 11 DXCC and 25 stations in total on 4m. 

Total opening time on 70MHz: Four hours (so far!). 

Great fun.

70MHz as seen on DXMaps on 24 May 2026

As the 70MHz opening continued a lot of OIRT broadcast stations were heard at times. 

Some stations on 4m were +32dB and peaking S9 on the S meter. That is usually the time for me to move up my "3-band plan" and look for 2m Sporadic E.  So I called CQ on 144MHz 24 times between 10:32 and 12:51 with no result. [Keep pressing on Jim].

Then IW0RGN answered my 2m call. Out of the blue, 1771km away in JN62. We had a quick QSO with +2dB at my end and -11dB at his. I heard him call CQ one more time and the event on 2m was over for me. 

144MHz as seen on DX Maps on 24 May 2026

Total opening time on 144MHz: 75 seconds. That is the way it is with 2m Es. The searchlight covered by the signal is small, often only extending to one station. It sweeps rapidly across the map. There is usually no large scale opening as you might get on 6m or 4m. So you have to keep calling CQ in the hope that one station hear you.

And one did. 

So there. 

I noticed 12 stations in "these islands" who were copying all those CQs, Gs, EIs, GIs etc. I doubt if they thanked me for keeping appearing in their waterfalls. However, it is only by calling CQ that anyone can get DX stations to notice that a 144MHz Es opening is happening. Otherwise we all just listen and then everybody misses the whole thing.

OIRT broadcast station seen at GM4FVM 24 May 2026

So that remains the basic 3-band plan. When there is an opening on 6m with stations reaching about +0dB I will go to 4m, and when 4m reaches that level too I will try 2m. Seeing OIRT stations would provide another suggestion that 2m is worth a try, beaming to the East and South East in that case. 

At all times I will strive for the treble on all three bands, though each contact, however mundane it might appear, is welcome. 

Post Script:  The 4m opening went on eventually for nine hours. I had to stop calling toward EA as I had worked everybody there was to work. After tea I came back into the shack and found some new stations on 70MHz and worked EA4TX at 18:17 and my old pal Fidel EA1HRR at 18:18. I then had a hunch that as I was +12dB with  EA4TK on 4m it might be worth giving 144MHz another try. Once again 4m pointed the way and at 18:23 I found EA4DS on 2m at 1717km in IN80. This was followed by EA1BHB at 18:29, and he was at 1504km in IN82. That was an eight minute 2m opening. Two openings on 144MHz in one day is good going, even if they only yielded three contacts.

2m Es is difficult to find without 4m providing the clues. Openings are brief and difficult to follow. I find them hard work but rewarding. Yes, it is good when a plan works out. 

Without a plan based on the clues from the lower bands I would be lost.

73 Jim

GM4FVM