Updated HF Propagation Charts from the UK

I have just updated my short-path propagation charts from the UK with the latest predicted smoothed sunspot numbers.

It takes about half a day to do - it took longer this time as I was using a new, faster laptop, but couldn't remember the log-in details for my server!

Anyway. they are done now. They are updated up to January 2027. Interestingly, the predicted smoothed sunspot numbers range from 120 for February 2026 to 96 for January 2027. These come from the Space Weather Prediction Centre in the US and are SIDC figures.

So it looks like we will have another good year of HF propagation, before the numbers star to slide further in late 2027. 

I still recommend both Proppy and VOACAP.com if you want detailed HF forecasts, or if you want to do long-path predictions. But for casual use my charts are fine, and produced using VOACAP.

Radials and Counterpoises

This is a talk I gave to Norfolk Amateur Radio Club at its annual Radioactive event. It looks at radials for ground-mounted verticals, including how many do you need and how long should they be. It references the excellent work done by Rudy Severns N6LF. Download the presentations in PDF format (760k). 

HF Propagation - what do the numbers mean?

This was the title of a talk and presentation I gave to the Nuneaton ARC in March 2025.

I have attached a PDF of the PowerPoint presentation, which can be downloaded here.

Without the talk, it may not make total sense, but it at least gives you a flavour of the talk and some insight into what some of the terms mean in HF propagation.

New worldwide 10m beacon list issued

RSGB’s Propagation Studies Committee (PSC) has released a new HF beacon list, with the 10m listings completely revamped.

The old list, which was started by Martin Harrison G3USF (SK), had been added to over the years, but was getting out of date. The only way to make it more accurate was to start again.

Use was made of the Reverse Beacon Network (RBN), which wasn’t available when the list was originally created, plus listeners’ contributions from around the world. 

I started by removing around 60 beacons that had not been heard for some time. Delving deeper it seems that a lot had been taken off the air, the owners had died, or their frequencies had changed.

Using the RBN gave a pretty good indication of what beacons are actually on air, plus help from a list compiled by Gary ZL2IFB filled in some of the gaps.

Beacons that are temporarily off-air have been left in, but marked in black.

While no list will ever be complete as changes take place around the world, I think the list is now far more useable. I’ll endeavour to make changes as and when they are needed.

The new beacon list can be found at:

https://rsgb.org/main/technical/propagation/propagation-beacons/

Help needed with Index Laboratories' QRP+ radio

I need your help! 

But first some background. The Index Laboratories' QRP+ is a 1990's 5W all-band QRP transceiver from the USA. I bought mine at a club sale and it was supposed to be working fine.

But it wasn't! Never mind, we all love a

challenge, don't we?

It seems that the SBL-1 mixer is a common failure point so a replacement was ordered.

The rig comprises four boards, which are stacked and have interconnecting leads.

It is relatively easy to pull apart, and the mixer is on the top board.

After a big desoldering struggle I fitted the new SBL-1 (U5), which brought the receiver back to life. Unfortunately, the TX still didn't work. Back to the drawing board.

The next stage was to replace the final PA transistor, which is on the lowest board. This is a IRF510 (Q9) and I ordered a few off Ebay. I fitted a new one and in tests I found that I could only get about 0.1W out! (on CW) with the gate bias backed off fully anticlockwise. 

Power out should be about 5W.

Anyway, that's as far as I have got. I have attached a link to the circuit diagram and would appreciate any suggestions.

Update

Well, some replacement IRF510s were sourced from the G-QRP club (thanks guys). Apparently, there are some "fake" IRF510s around that don't play well with RF.  After pulling the radio apart (again) and replacing the transistor, it was a little better - about half a Watt output. Anyway, to cut a long story short I have passed the radio to another G-QRP club member and I hope he has more luck than I did! 

Update to UK propagation charts

I'll freely admit that my UK propagation charts had been a bit neglected over the past year. But not any more!

I've now updated them until the end of 2024 with new predicted smoothed sunspot numbers.

I've also fixed a problem with the Kp graphs. They now appear, along with solar X-ray and proton flux graphs. This was because the US Space Weather Prediction Center had stopped the production of the previous Kp chart.

I still recommend both Proppy and VOACAP.com if you want detailed HF forecasts, or if you want to do long-path predictions. But for casual use my charts are fine, and produced using VOACAP.

Leave a comment if you find them useful (or not!).

Incidentally, the SSN charts I used show that the expected solar maximum is the middle of this year.

Preparing the GB2RS propagation report

Attached below is a PDF (14Mb) of the presentation I gave on 15th April 2023 after the RSGB AGM.

It looks at how we prepare the weekly propagation report for the RSGB's GB2RS news report. It contains a lot of useful URLs to sources, data and programs that people might find useful.

Steve G0KYA

Download GB2RS_Propagation.pdf