Monday, 30 March 2020

Understanding HF Propagation video released

I've just published a 40-minute video entitled "Understanding HF Propagation" on YouTube.

This presentation was originally produced for use with clubs around the UK and has been used by more than 100. 

With the current Covid-19 restrictions in the UK, it looks like club meetings aren't going to be taking place any time soon, so I've released it on YouTube.

I may do some further videos over the next few months - it depends on how long the restrictions last!


Steve G0KYA

Monday, 21 October 2019

Range of HF propagation tools launched

There is now a range of online propagation tools available from the RSGB's Propagation Studies Committee, including Proppy for RadCom, VOACAP for RadCom, Predtest and Propquest. All very popular according to the feedback.

We highlighted these at the recent Newark Hamfest.

RSGB has now set up quicklinks to each of the tools, which will make it easier in the GB2RS audio bulletin. These are: 

Shows real-time critical frequency and MUFs over various path lengths. Excellent tool for HF users.

Designed by Gwyn G4FKH, calculates the probability of propagation over different paths and for different modes. Includes point-to-point and animated displays.

VOACap for RadCom
Shows the probability of propagation to 28 different locations around the world – the same locations used in the RadCom predictions. Can be tweaked for your particular station including mode, gain and power.

Proppy for RadCom
Uses the latest ITURHFPPROP tool to calculate the probability of propagation to the same 28 locations used in RadCom.

Sunday, 10 March 2019

2019 Commonwealth Contest and QRP

My Yaesu FT-817 and Winkey

This weekend has seen the Commonwealth Contest 2019. I documented my 2018 attempt on the blog, and was keen to give another go this year.

Last year I used my Icom IC-756 Pro 3 wound back to 5W, but this year decided to use my Yaesu FT-817 for a real QRP approach. I bought a USB lead for it this year to give full computer control with N1MM and decided to use my Winkey for full auto CW .

This year I had a slight change to my antennas. Out went the end fed half wave (with 80 loading coil) and in came a 66ft OCFD with the apex at about 8m. Also new was a quarter wave vertical for 20m, erected for the weekend on a 10m fishing pole - more of that later.

The contest ran from 10am, but at 9.30am I was struggling with the computer and interface. Stupid me forgot to turn off the keyer on the FT817 - duh!. Soon we were under way.

The contest got off to slow start with my 5W struggling to break through. Many stations just couldn’t hear me. The quarter wave vertical for 20m turned out to be a noise magnet - almost S8. I  decided to abandon it quite quickly.

After an hour I had a few stations in the log - 5B4AGN (Cyprus) and 9H1CG am (Malta), but nothing better. 3B8XF Mauritius (G3TXF) was audible, but I couldn’t break through. Same with ZF2CA Cayman Islands (both 3B8 and ZF were worked last year).

The afternoon saw Canada romping in and I ended up doing an hour at about 10-11pm, clearing up the UK HQ stations.

Sunday started at about 5.30am and a few more Canadians on 40m were cleared up. I then had a big breakthrough - VK4CT on 40m. It wasn’t easy, as they needed three or four repeats on their serial number, but we got there eventually.

So there you go - 34 QSOs in total, which doesn’t sound much, but I didn’t take part for the full 24 hours and it is HARD work with only 5W. Peter M0RYB, a fellow Norfolk Amateur Radio Club member, cleaned up with 70 QSOs in the QRP section. Must find out his secret!

Note: The FT-817 isn't much of a contesting radio. I found it struggled with a nearby 400W station and also found the 500Hz filter a bit too wide. Might be back to the IC-756 Pro next year.

Monday, 4 February 2019

HF propagation charts updated

I have just updated my HF short-path propagation prediction charts for the UK (accessed via a link on the right).

I had to update them with the latest smoothed sunspot numbers for the next 12 months.

This is a little depressing as after May 2019 the predicted SSN falls to "one" and stays like that for the rest of the year! Sunspot minimum is currently thought to be later this year, but could spill over into 2020.

These charts are meant as a rough guide. Other tools that are available are:

1. The VOACAP RadCom prediction tool - this replicates the locations found in the monthly RSGB publication, but lets you choose your own mode, power and antennas to give more accuracy.

2. The tool - this tool, developed by Gwyn Williams G4FKH, uses the latest ITURHFPROP prediction engine to let you produce point-to-point or area propagation predictions, again with full control over the input parameters.

3. Propquest - this is a near real-time tool, developed by Jim G3YLA, that shows the critical frequency and extrapolated maximum usable frequencies available over different path lengths. The critical frequency (the frequency at which a radio wave launched vertically stills gets returned to Earth) is derived from ionosonde data, mainly from Chilton and Fairford.

It should be your first port of call to see what conditions are like. In the summer it also has predictions for Sporadic E, courtesy of Jim.

Steve G0KYA
RSGB PSC Chairman

Monday, 21 January 2019

Yaesu FT-991A firmware update warning

I have owned a Yaesu FT-991A for about two years. I have to say that I really only use it on two metres. It isn't a bad radio, but it can be fiddly and you have to get used to going through lots of menus to do what you want it to do.

As such I tend to use my Icom IC-756 Pro 3 as my main HF rig (unless I'm using one of my QRP rigs like the Elecraft K1, YouKits HB1A, QCX, MTR etc). Use the QRP tag on the right if you are interested in reading about them.

Anyway, I recently tried to use Yaesu's Fusion mode as we have a new Fusion repeater (GB7NM) about 10 miles from me.

I wasn't impressed with the audio though. Half the time it was unintelligible and pretty awful to be honest. I did wonder if the signal strength is sufficient, but it is S9 +30db. Also, I live about half a mile from the police headquarters and do suffer some desensing on 2m if I use a cheap handheld like a Baofeng connected to my 2m antenna. Perhaps that's the problem.

However, I checked and found that the FT-991A's firmware (including C4FM) was out of date and thought that an update might improve things.

So, following the instructions, I first uploaded the main firmware - and this is where I came unstuck. Once I had completed it I rebooted the radio, but it wouldn't - all I had was the Yaesu screen.

Arrrgghh! Now what. Reading around the internet I found that you have to upload all four of the Yaesu firmware updates - the main, the TFT screen, the DSP and C4FM.

If you don't the radio won't work.

To be fair it does say in the instructions:

MAIN Ver. 02-01 also requires TFT Ver. 02-00; also DSP Ver. 01-11 and C4FM DSP Ver. 04-15.
If your FT-991A does not have them already, please update all firmware, they must be used together.

Once I had uploaded all four and reset it all was fine again - apart from I had lost all my settings.

Another quick hint. If you have memories loaded use VK2BYI's FTRestore software before you start the firmware update and make a copy of the memories. Once you have made the firmware updates you can then reload the memories and save yourself a lot of time.

Anyway, after two hours of messing around I had the radio back the way I wanted it.

So is Fusion better now? I still don't think the audio quality is that good, although it my be a bit better. But at least the radio isn't bricked!

Thursday, 1 November 2018

Autumnal HF conditions show sunspots aren't everything

Click to enlarge

Don't you just love it when something works! I took down my multi-band end fed half wave (EFHW) antenna last weekend and replaced it with a home-made 40m off-centre fed dipole (OCFD).

The EFHW worked, but I was never happy with the performance. This may be due to the inverted L configuration or the compromise 49:1 ferrite-based Un-Un. Either way, I felt I was missing out on some DX and was keen to try something else for the Autumn/Winter.

The 40m Windom is about 66ft long and has a home-made 4:1 Guanella balun made with two ferrite cores. It is fed at the 41%/59% point so it covers 40, 20, 15 and 10m with an SWR below 3:1 and the other HF bands with an ATU.

The apex is at about 8m with the ends down to about two metres, so not ideal.

Nevertheless, in back-to-back WSPR tests it proved to be better than my W5GI dipole that goes over the roof by about 7dB on average. This was good as the EFHW was mostly down on the W5GI.

Anyway, I thought I would leave it running on 20m WSPR for 24 hours to see what it could pick up. This was with zero sunspots, but a Kp index of 1. I was delighted to see that I had been picked up as far afield as Japan, Australia, Alaska, Antarctica and Brazil. The furthest west I got in the US was Utah.

So, I'm a happier bunny. I might return to the multiband EFHW one day, perhaps looking at different ferrite mix configurations for the Un-Un, but for now I'll stick with monoband EFHWs with tuned iron toroid/capacitor matching units that work well.

The OCFD can stay up for a while - you know that the best antenna you can have is either the one you just took down, or the one you are going to put up, not the one you are using!

Sunday, 26 August 2018

Predicting space weather – and how to get it wrong!

Space weather prediction is an inexact science. We still don’t fully understand the Sun or how it works.

This means that predicting what HF radio conditions are going to be like over the next seven days can be challenging – especially when you have to produce the forecast a couple of days before it is published.

This week was a perfect example of how to get it wrong!

I prepare the HF part of the RSGB’s GB2RS Propagation Prediction forecast on Thursday afternoon. Jim G3YLA looks at VHF and Sporadic E, before it is sent to John G4BAO who adds some more info on any microwave propagation such as rain scatter and also adds the EME report.

I then edit it, add my HF predictions and send it to RSGB HQ so it can be collated, published and sent to GB2RS readers on Friday.

Sunspots on Thursday 23rd August 2018.
At that point this week the Sun looked fairly innocuous with one tiny sunspot group, a solar flux index of 70 and a sunspot number of 15, representing one sunspot group with five tiny spots.

There were no obvious coronal holes and NOAA predicted the K index would likely be two all week due to a lack of geomagnetic disturbances. The US Air Force agreed.

So far so good!

At 04:45UTC on Monday 20th NOAA had reported:

“Region 2719 (S06, L=133, class/area Bxo/010 on 19 Aug)
developed in the SE quadrant on 19 Aug. No significant flare events
occurred from either region. Other activity included a filament
eruption centered near S11W04 observed lifting off the solar disk at
approximately 19/0538 UTC. An associated coronal mass ejection was
observed off the SW limb in SOHO/LASCO C2 imagery at 19/0812 UTC.
WSA/Enlil modelling of the event suggested the ejecta was primarily
directed westward of the Sun-Earth line and is not expected to cause
any significant effects.”

So the CME wasn’t earth-directed so shouldn’t be a problem – bear with me!

The NOAA report for Monday 20th August said there were no events.
The NOAA report for Tuesday 21st August said there was an RSP (a sweep-frequency radio burst) at 18:46UTC observed at Palahua, Hawaii, USA
The NOAA report for Wednesday 22nd August said there were no events.
The NOAA report for Thursday 23rd August said that at 20:23UTC on Thursday evening the older region 2719 emitted an an “A class” X-ray solar flare. “A class” flares are the weakest and it was after sunset in the UK so didn’t have any major impact for us according to the ionosonde data.

But there were further A class flares on Friday 24th August, which were at 12:47-12:50 UTC, 21:54-21:58 UTC and 21:57-22:01 UTC.

The Chilton and Fairford Ionosondes in the UK show Friday’s flare’s effect at 12:47 as there is a gap in the data.

You can see this at Jim G3YLA’s Propquest site at:

But by Saturday 25th August a new large sunspot
group had appeared.
By Friday another new sunspot group (2720) had emerged, which grew rapidly and by Saturday it was quite large. Sunspot AR2720 is not only large, but also strange. Its magnetic polarity is reversed. The North and South ends of its magnetic field are backwards compared to the norm for sunspots in decaying Solar Cycle 24.

So could AR2720 be from the next solar cycle, Solar Cycle 25? We’ve already had one reverse polarity sunspot which has been attributed to Cycle 25, but that was last year. This is going to be discussed over the coming weeks.

Action on Friday 24th August continued.

From 02:00UTC a series of solar flares were recorded, mainly from the new region 2720. These were B-class solar flares.

By the early hours of Sunday morning, 26th August the K index had started to climb, peaking at Kp7 at 03:00 and 06:0UTC. The bands on Sunday were lousy with a lack of signals across the board in the UK as the ionosphere collapsed. The 14.100MHz IARU beacons were all inaudible.

The Kp index hit 7 in the early hours of Sunday
26th August 2018.
A sweep with my SDRPlay receiver and SDRUno software saw very few signals on 20m at all and virtually nothing higher in frequency. There were a few weak and watery CW signals from Germany on 40m.

So what was the cause?

NOAA now says there had been an earth-directed coronal mass ejection on Monday 20th August that no-one seemed to comment on at the time. NOAA’s own records don’t show any solar flares on Monday August 20th – see (

So was it this CME or the one on the 19th that is now reported as causing the high-speed solar wind stream that brought about the Kp7 event and auroral conditions? The experts seem to think so – now!

Or was it a CME as a result of the solar flares on Friday 24th August? That to me would seem more likely and fit in with the roughly two-day solar wind transit time to Earth. described it as a “surprise geomagnetic storm” and I think that’s a pretty apt description as no-one predicted it.

If that is the case there is no way I could have known about it when I filed the copy to RSGB on Friday morning. This report predicted quiet geomagnetic conditions for the week commending Sunday 26th August – I don’t think so somehow!

Oh, the joys of space weather and HF radio propagation forecasting!