AmateurRadio.com

We are entering the Sporadic-E season, the favourite time of the year for those who enjoy operating the VHF bands. As Roger G3XBM suggested today, more stations this year will be using WSPR on the 10m and 6m bands, so many openings may be detected that would otherwise be missed. I am WSPRing on 10m at the moment, and will probably move up to 6m later on once 10m starts opening on a regular basis.

However, my first love will always be 2m. From this QTH surrounded by hills Sporadic-E is the only type of propagation that allows me to work DX on that band. On 2m, Sporadic-E openings are much rarer because much smaller patches of the Sporadic-E clouds are dense enough to reflect signals at this frequency. This makes propagation between two points on 2m much more fleeting. A station can be 59+ one minute and gone the next, which makes it essential to keep QSOs short and sweet: report, locator, and name only if you are sure you have got the time.

Some people are planning to use WSPR on 2m as well, but because of the fleeting nature of propagation I am not convinced that the 2 minute periods of WSPR make it the most appropriate method of detecting propagation on this band. I think it might be more fruitful to monitor 144.8MHz which is the APRS frequency in Europe.

APRS packets take only a second or two to send, so you don’t need propagation to be good for two whole minutes to receive one. Packets do need to be received clearly, but the “strong or gone” nature of Sporadic-E on 2m suits that quite well. The main difficulty is knowing the location of the station that sent the packet you heard, since it could well be a digipeater retransmitting a packet sent from somewhere else.

There used to be a website that displayed a propagation map based on APRS packets received. But in the last few days it appears to have gone QRT, which is rather a shame. But if you are in a location that doesn’t normally hear much APRS activity, even just hearing a number of signals going “braaap” on 144.8MHz could be the alert you need that some unusual propagation is about.

If anyone has any other ideas on how to improve the detection of Sporadic-E on 2m without sitting in front of the receiver listening to band noise for hours on end I’d be interested to hear them. If you aren’t familiar with this mode of propagation and how it works and would like to learn more about it then there is an article about Sporadic-E on my website.

On the WSPRnet website DM1RG posted some results obtained using a 30m dipole 1.3m long, the “Kurz Geratener Dipol“. His 5W signal made it all the way from Germany to Australia. He finds the KGD to receive only 3 to 5dB worse than his “big vertical antenna.”

I tried translating the article about the KGD using Google but it didn’t make enough sense for me to understand how to make one. Perhaps someone will figure it out and publish a better explanation. It looks to me to be an interesting idea for anyone with antenna restrictions or simply wanting a second antenna so they can run WSPR or monitor a band while they operate somewhere else.

I heard a little bit of sporadic-E propagation on 10m this afternoon. Tuning around the beacon segment I heard the beacon DK0TEN on 28.257.5MHz quite strongly for about a minute before it faded away.

There have even been some contacts made and beacons heard on 6 metres, according to VHFDX.info. Let’s hope for some good openings on VHF this year.

I was tuning around the top end of 10m yesterday and noticed a lot of strong bubbly warbly noises, the unmistakable sound of switched mode power supply interference. It didn’t take long to track this down to the power supply for my QNAP TS-109 Turbo Station.

The TS-109 is a network attached storage device. But it is actually a small computer with a big hard drive, running Linux. I use it mainly as a backup drive for all our PCs, but it also hosts the shared documents folder so that we can easily exchange files from one computer to another. It runs a script that updates DynDNS when our IP address changes, which it does quite often at the moment. I could even run a web server on it if I wanted. So it really needs to run all the time. But the amount of interference it produces isn’t acceptable. I tried adding some clamp-on ferrite suppressors but they didn’t make much of a difference.

The power supply for this device is a plug mounted switched mode supply rated at 12V 3A. This is probably over-generous as the specification for the TS-109 gives the power consumption as 14.4W in operation. There are plenty of alternative 12V switched mode supplies available but I have no way of telling whether they would be better or worse than the manufacturer-supplied one as regards RF interference.

The only transformer based power supplies capable of supplying this sort of power are CB radio power supplies such as those sold by Maplin which have a 13.8V DC output. QNAP doesn’t, unfortunately, specify a voltage range for the Turbo Station so I don’t know if this higher voltage would be permissible. It would be very convenient if I could use the power supply I made for my QRP K2, which these days just keeps the K2’s battery charged up, but the output from that is 14.2V.

Switched mode power supplies really are the bane of the radio amateur’s life. I don’t know how to solve this problem at the moment, except to switch off the TS-109, which is inconvenient.

One K3 setup adjustment that I have never done is to check the power level of my K3 transverter output, because I don’t have an RF millivoltmeter. I do, however, have an Elecraft DL1 dummy load which has a test point fed by a 1N5711 diode and capacitor. You can take voltage readings there, and then calculate power using the formula:

Power = (( Voltage * 1.414) + 0.15) ^2 / 50

and I normally use this whenever I want an accurate power measurement rather than rely on the readings of analogue meters.

What I don’t know is whether this is accurate enough to measure power at levels as low as 1mW. So I asked the question on the Elecraft email reflector, rashly forgetting that the function of of the reflector is for users to flame each other and speculate on or redesign Elecraft products. Don, W3FPR, who was usually good for an answer to a technical question, has left the reflector after he was flamed for some imagined breach of netiquette. Frankly, the reflector is now worthless. I wish Elecraft would create an announcements-only mailing list so that one could stay informed of new developments and firmware updates without having to see all the ego clashes and endless questions about problems with USB serial adapters.

When I measured, using the DL1 and my DVM, the output from the K3 transverter port with the level set to 1mW, I got a reading of 36mV. Plugging that into the formula, I get 0.8mW. But the 0.15 is, I presume, a “fudge factor” to compensate for the voltage drop in the detector diode, which gives me a result of 0.45mW even if zero voltage was detected. So I’m wondering if my 0.8mW is within the limits of error of my measurement method and that I should leave my transverter drive level as it is. I assembled my K3 myself and the transverter board was added later so I don’t believe the level has ever been set at the factory.

On a clear day from here you can normally see at any one time two or three vapour trails from transatlantic jets at 35,000 feet on their way to London’s airports. For five days there have been none. The weather has been fine and the sky blue, so blue that it’s easy to doubt whether the density of dust from the Eyjafjallajokull volcano in Iceland poses any real threat to aviation, or whether it is just bureaucrats being over-cautious.

Whatever the risk, the aviation ban is real and there can be no-one in Britain who has not been affected by it one way or another. The first effect we noticed was when we went to a classical music concert last Friday in Carlisle. The piano soloist was unable to get there so the Mozart piano concerto was played by a stand-in.

I received an email from one Hong Kong eBay seller to tell me that the programming interface for the Motorola radio I bought at Blackpool which I ordered from him would take longer to arrive. I expect other items I have ordered from eBay and elsewhere, including a transmitter module for my dedicated Echolink node radio, will be similarly delayed, as there is no air mail. We take for granted that we can order things from China or the USA and have them in a few days. Not any longer.

Friends of ours who are due to return from Ukraine tomorrow are probably not going to be able to make it unless London Luton airport is miraculously opened. They are due to return to work on Thursday and are very anxious not to provide their employers with an excuse to terminate their contracts.

That’s the situation now, but with seismologists saying that the volcano could continue to erupt off and on for the next year or two and even suggesting that another, larger Icelandic volcano is due for an eruption, what is the future for the airline industry? If there’s a high probablility of getting stranded abroad like so many people are now, how many are going to decide to change their travel plans and stay close to home for the next few months? I will, for sure.

I dare say canny investors will be selling airline shares and investing in shipping. And I don’t suppose it will be long before the first package holiday companies start going bankrupt because of all the refunds and cancellations. Like the banking collapse, I think this is another event that is going to have permanent repercussions.

Trust Nature to cut us down to size. We humans think we are so powerful we can end global warming, yet in a few hours the earth achieved what governments alone could never have managed – a complete grounding of aviation. I suspect that a really big volcanic eruption could have a bigger impact on global climate than any of the measures agreed by the politicians.

In a comment to an old posting about D-Star in G4VXE’s blog, Lee N2LEE accuses me of being closed to new ideas. Does it matter that the AMBE codec is patented if it is the best one for the job, he asks? And how can you compare Echolink/IRLP to D-Star when D-Star is an digital end to end system with routing, linking and networking built in to the system so you can just enter someone’s callsign and the network will find them automatically?

To me, ham radio is not and never has been about reliable point to point communication. Communication is just the end-product of a process of experimentation and construction, or a pastime (think contests, DXing) where the unreliability and unpredictability of it is what makes it a challenge.

D-Star’s use of a proprietary codec closes that aspect of the system to experimentation. It doesn’t even permit interested amateurs to look at the code and see how it works. This is contrary to the spirit of amateur radio and the openness that has facilitated most developments to date by letting one idea lead to another. But to be honest I’m not all that bothered about the issue because codec technology, whether proprietary or not, is a closed book to most. I am more concerned about the possibility that digital voice modes might one day make analogue modes obsolete so that building a simple phone transmitter using SSB, FM or AM becomes a pointless activity. Ham radio does not have to slavishly adopt new technology, especially if that technology forces more of us to become appliance operators by making simple rigs that anyone can build obsolete.

As for digital end to end routing, why do we need it? We already have a system that can do that. It is called the mobile phone network. I didn’t get into ham radio in order to be able to do something ordinary people can already do. I want to be able to do things that they can’t. The unpredictability of propagation and the uncertainty of who you might work on a given band at any time are what makes a ham radio contact more interesting and more of an accomplishment than making a phone call. D-Star may be very clever technology but what it delivers is not what ham radio is about.

If the time ever comes when I think to myself “why am I struggling to make this contact on 20m SSB or whatever when I could simply type the guy’s call into my D-Star radio and have a comfortable chat” then that is the day I will give up the hobby for good. And I make no excuses for resisting the adoption of technologies that will bring that day closer.