Friday, 21 October 2022

Autumn 2022 HF popagation charts updated


I have just updated my propagation charts for October, November and December 2022 with new sunspot numbers. 

I will update the Spring 2023 charts when we get a little closer as they are likely to change as we head towards the maximum of solar cycle 25. 

Anyway, it is nice to see some good predictions of DX on 10 metres and if the past two weeks are anything to go by they are pretty spot on with very loud signals from the USA. 

ARRL's W1AW's CW practice files were romping in the other day on 28.0675MHz Nice to see 10 metres doing what it does best! 

Click here for the charts or use the link on the right-hand side.

Friday, 18 March 2022

Repairing a MFJ-1786 magnetic loop

I just wired up my MFJ-1786 magnetic loop, which hasn't been used for years. Unfortunately, it looked like the loop controller had gone U/S. 

The meter lit up, but pressing the loop buttons had virtually no effect. The amber lights flicked slightly, but they were not so bright as I remember them, and the motor didn't turn. I got hold of a schematic, but it is way more complex than I thought it would be. I first changed the only electrolytic capacitor in the unit as it was getting quite old, but it made no difference. 

I then stripped the antenna and made sure it was all OK. Connecting a 9V battery made the motor turn, so I sprayed the motor with grease and put it all back together. Turning to the controller again I first changed Q1, but that made no difference. Then I changed Q5, but nope! So I moved on to the U5 78L12 voltage regulator, which is fiddly job as it is an 8pin SMD. 

And low and behold it works! I just need to fix the power meter, which displays reflected power, but not forward, but that can wait until another day. Then finally I can mount it outside for final testing. I've attached the MFJ-1786 schematic as this was quite hard to track down - might come in handy for someone in the future.  Click on the image above to see a larger version.


Well, it wasn't a diode that was stopping the meter from working, just a poor connection. 

So I now have some spare diodes for the future! I've uploaded a higher resolution version of the schematic too.

Steve G0KYA

Thursday, 18 February 2021

HF propagation charts updated for 2021

I've now updated my propagation prediction charts for 2021 with the predicted smoothed sunspot numbers from NOAA/NASA.

So that's a chart for every hour, for every band and for every month, or more than 2,300 charts in total! The process is fairly automated, but it still fairly tedious and takes about a day to do.

The charts are useful as a quick guide to what parts of the world may be workable and which aren't. If you want more accurate charts then the ITURHFPROP-based or the VOACAP-based websites are better.

I may need to update them as the year progresses as we get a better idea of how Solar Cycle 25 pans out. At the moment it isn't looking too good. December 2020 saw a sprinkling of SS25 sunspots with a corresponding rise in HF activity. But since January is has been pretty dire really with long periods of no spots 

Anyway, to avoid confusion, I have updated form February onwards. This means that January is actually for 2022. 

The charts are produced using Hamcap which is a VOACAP-based application and they are for short-path only.

Wednesday, 24 June 2020

VHF propagation video released on YouTube

As a result of the success of our HF Propagation video on YouTube, which has had 2,000 views in two months, the Propagation Studies Committee has now launched a 20-minute VHF propagation video as well.

The video was originally produced for club presentations, but with Covid-19 and the lockdown, it wasn't getting much use.

So if you have never heard what an auroral contact sounds like, for example, now's your chance!


Steve G0KYA
Chairman, RSGB Propagation Studies Committee

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.