At the moment, I scan the 70cms band on a pretty regular basis and every so often, the radio will stop on 433.475 and 433.525 MHz. The signal sounds like a weak digital transmission and it's only there occasionally.
I thought perhaps it was due to an out of band signal and the receiver was being overloaded. Having said that, the Alinco 605E seems like a reasonable radio and the front end doesn't seem to be wide open like some of the handhelds.
After a bit of digging, I discovered that there is an allocation for low power device on the 70cms band. It's called LPD433... https://en.wikipedia.org/wiki/LPD433
This is the frequency chart which as you can see goes from 433 to 435 MHz.
I knew that some car key fobs and remote devices were using the band but I hadn't realised it was so extensive. Perhaps that is the reason behind the mystery signals?
What I didn't know was that in Europe, this allows licence free voice communications on 70cms.
"LPD hand-held radios are authorized for license-free voice communications use in most of Europe using analog frequency modulation (FM) as part of short range device regulations, with 25 kHz channel spacing, for a total of 69 channels."...from Wikipedia.
I noticed that Amazon are selling a dual 446 / 433 MHz radio as well...
Considering how easy it is to buy a radio, I wonder will there be more unlicenced operation on the 70cms band in future?
Since I returned to the radio, I have been listening to the 2m and 70cm bands. While the level of activity on FM seems pretty low, the repeater infrastructure on the bands is very impressive.
The largest of these is the Southern Ireland Repeater Network which links up multiple repeaters. i.e. a signal on one repeater appears on all the others.
On Friday the 18th of November, I had the rig turned to 28.2150 MHz, the frequency of the GB3RAL 10 metre beacon in the UK.
I was using Spectrum Lab on the PC with the microphone resting on top of the HF rig....an easy way to monitor a frequency while working away on something else. If there is anything there buried in the noise, it will usually show up on the screen.
I've listened to this back in 2008 and found it hard to get a positive ID. It seemed to be just a carrier without any CW.
This time around, I got 'AL' on cw within about 20 minutes so I knew I was hearing it. There were plenty of pings over the space of an hour and then at about 10:28 UTC, I got this fine 4 minute burst...
Right hand side shows the audio freq in Hz.
The tone was easy to hear at times as it transmitted "GB3RAL IO91IN". It certainly wasn't a huge signal...maybe 419 at best but clear all the same.
I'd imagine it would have been really easy to make a contact on a digital mode like JT65.
It was only afterwards that I noticed that the Leonid meteor shower peaks on the 18th of November so perhaps it was due to one of those.
On a positive note, it's good that the new 10 metre vertical seems to be working well.
With the Solar Flux index down at 78, there isn't much in the way of F2 propagation at the moment. However, there was some Sporadic-E today.
In the morning, I heard the beacon on the Faroe Islands which is always interesting as it's to the North.
EI7GL-@ 28282.5 OK0EG/B 10:38 19 Nov JO70weIO51tu Czech Republic
EI7GL-@ 28237.4 LA5TEN/B 10:32 19 Nov JO59jpIO51tu Norway
EI7GL-@ 28235.0 OY6BEC/B 10:26 19 Nov IP62oaIO51tu Faroe Islands
I also left the rig on the WSPR frequency for a few hours and heard the following.....
It was one of the days where the casual observer might say the band was dead but there were weak signals there all the same. As you can see from the list, some of these were running less than 1 watt.
Interesting Sporadic-E conditions for this time of year. It also suggests that the new 10m vertical antenna is working just fine.
The long process of getting back on the air continues. I've put up antennas for 2m and 70cms in the attic of the house so at least now I have something that might be considered semi-permanent. If I go off the radio again, it's not such a big deal to get going again and the aerials won't get destroyed by the weather.
In the last week, I checked the Westflex 103 coax cable going to where the old CB vertical used to be. Using my old home brew power meter and my old Yaesu FT-290R, I established that the loss for the 20 metres or so of Westlex 103 was about 2dB at 145 MHz. This means that it should be well under 1dB at 28 MHz and that includes having a back to back SO239 connector in line. So the coaxial cable is working fine and shows no sign of water ingress.
About a fortnight ago, I purchased a CB half-wave vertical from Long Communications in Donegal. The model was a Venom which I believe may be from a company called Sigma.
Considering it was only €35 with an additional €12 for delivery, it's hard to say it is in any way expensive. In contrast to some of the verticals for the HF bands, it's incredibly cheap.
Some of the specs should be taken with a pinch of salt.
Power Handling...1000 watts.....I doubt it. 100 watts is fine but I'd have my doubts about anything close to 1000.
Gain...4.1dB.....Sounds great but it's a half-wave! 0dBd or 2.15 dBi at the most and that's if you ignore matching losses.
Frequency....26 to 28 MHz.... My tests shown below suggest that it won't be resonant anywhere near 26 MHz. Without an antenna tuner, I think 27.0 to 29.7 MHz would be part of the spectrum that the antenna could be adjusted to.
Construction and Assembly.......All the parts come in a small plastic bag which includes two U-Bolts, three screws, three washers, 3 nuts, 4 jubilee clips and a small plastic seal for the top of the antenna. All pretty obvious and the antenna can be assembled in about 10 minutes.
There are Blue marks on the aluminium sections to show how far each section should be inserted into each other.
This YouTube below from someone in the UK shows what it looks like out of the box including the Blue marks for adjustments.
One of my biggest fears was that the antenna would be really flimsy once it was constructed. To be honest, it looks fine. I can't really say the construction matches the cheap price, it seems fine.
Tuning...I mounted the antenna on a 4 metre pole and checked the VSWR with the internal meter on the Kenwood TS690. When I had the lengths adjusted to the Blue marks, the centre point seemed to be around 28.0 MHz. I then shortened the antenna so that the VSWR plot now looks like this.
Some observations and notes....
1) As I shortened the antenna the VSWR curve below the centre frequency seemed to match that above. As a result, I have inferred the plot below 28.0 MHz as I cannot transmit there.
2) The 1:1.5 VSWR bandwidth is 1.3 MHz which seems pretty good.
3) The top section of the antenna must be adjusted by 4 cms to move the centre frequency by 100 KHz. So in other words, if you wanted to move the centre frequency up by 300 KHz then you would make the antenna 12cms shorter.
4) If the length of the antenna was assembled to the Blue marks then the centre frequency was 28.0 MHz. This means the VSWR was at or below 1:1.5 from about 27.35 to 28.65 Mhz. This might be an issue for someone who wants to use the bottom end of 27 MHz as there wasn't much scope for making the antenna much longer. It should tune up fine with an antenna tuner but I'd guess most CB stations would be unlikely to have one.
5) My antenna was mounted at 4 metres above ground level. The VSWR and centre frequency may well change if the antenna was at different heights.
Performance.....Too early to say but I am hearing local Churches broadcasting at the top half of 27 MHz from about 50-60 kms away so it seems reasonable. It is certainly no worse than the old CB half wave I used to have.
Overall.......Time will tell if it survives the Winter gales but the mechanical construction seems reasonable. If I had it way above the house then I suspect it wouldn't last long. But at 4m, I would expect it to last the first winter anyway. Other than that, the performance seems as expected.
After my four year absence from the radio, the main task now is just to get some of the gear working again. Over the last two weeks, I managed to locate the microphone for the 2m/70cm dual band rig and I have put up a vertical half-wave in the attic of the house. Not perfect but at least it gets me on the air again.
Even though the aerial is indoors, I can hear some signals from repeaters and simplex stations from about 100kms away. One of those is the Limerick repeater on R5 (145.725 MHz) which is just over 100kms to the North.
The signal is about S3-5 which means it's clear and easy to listen to but I'd probably need the full 50w to work through it.
I have also managed to get the rig set up to scan both 145 MHz and 433 MHz bands which lets me see who is about. The level of activity is pretty low so it spends a lot of time scanning.
I have noticed though that it sometimes stops on 145.725 MHz with the unmistakable sound of CW coming through. It's not CW on FM but I can hear the white noise on FM getting pulsed by a CW signal. Sure enough, when the repeater opens I can hear the CW beating with the signal and the sound of the CW frequency changing slowly....a sure sign of a satellite.
I came across this a few weeks back when I went looking for info on the Cornwall beacon on 50.042 MHz. I ended up watching a video for the AGM of their Beacon/Repeater group...as you do :o)
During the presentation, someone mentioned that there was interference to their local repeater GB3NC on 145.725 MHz from a new Chinese satellite.
Sure enough when I heard the signal today, I looked up the N2YO satellite tracking website and it was out over the Atlantic and within range. If you want to see where it is at any time or to see when it might be visible, go to http://www.n2yo.com/?s=40911
It seems that a bunch of Chinese satellites were launched in September 2015 and their up links and down links are shown below....
As you can see, the XW-2B has a beacon on 145.725 MHz which is the one I was hearing. The image below shows what it looks like with some specs...
XW-2B – Micro-satellite architecture – Dimensions: 250Lx250Wx250H mm – Mass: 9kg – Stabilization: three-axis stabilization system with its +Y surface facing the earth – Antenna: Deployable antenna, one 1/4λ monopole VHF antenna with max.0dBi gain is located at +Z side and one 1/4λ monopole UHF antenna with max.0dBi gain is located at –Z side, close to the each edge of satellite CW Telemetry Beacon: 50 mW, 22 wpm
Essentially it's a 25cm cube with 50mW into a quarter wave whip on 145 MHz. It's pretty amazing to hear it with just a half-wave vertical in the attic.
I heard today that Bernie O'Sullivan EI6AX has passed away (Notice). Bernie used to be a regular on the HF bands and always called into the IRTS News on 40m every Sunday morning. Maybe it was because of his location but he was always one of the strongest signals on the band.
Living in Cahermore on the Beara Peninsula, he was also one of the most remote EI calls in the country.
It can often be useful to listen on the 27 MHz CB band to see if propagation is likely on 28 MHz, especially when the 10 metre band seems dead. The fact that it is slightly lower in frequency can mean that the CB band will open before 10 metres for F2 and Sp-E propagation.
Many of those CB operators who are into DX-ing use 'Division' numbers. For example, if you heard '26 AB 123' then that person would be from England.
Four years....Yes, four long years since I posted anything on this blog let alone turn on the radio.
It's hard to exactly why I was off the air for so long but the main reason is that there are so many other things happening. In a world of Facebook, Twitter, YouTube, TV and all the other stuff, there seems to be less time for things like radio. I guess the biggest single reason is that I just got out of the habit of turning on the radio and using it.
In the last two weeks, I had to do some paperwork for something else and this get me to sort out all my Comreg and IRTS paperwork and notices. That single act alone got me thinking about the radio again.
On the Comreg front, I managed to find my PIN number and I was glad to see that I still had a licence when I logged onto their site! :o)) I wasn't sure if it had lapsed or not but the renewal is still a few years off.
With the IRTS, I rejoin every year but I'm always late. It was always a case of rejoining...looking back through a years worth of newsletters online...and then forgetting about it again. Looking back through the newsletters this time, one thing that struck me was the number of people who had passed away.
Antennas.......On the antenna front, the four years have taken their toll. I no longer have any external antennas as they have been damaged in various storms and I've taken them down. The only antennas I have are the two in the attic of the house....a 2 element beam for 50 MHz and a vertical half-wave for 144 MHz. The next step will probably be to get a vertical up again for 28 MHz.
Another good day on the 10 metre band with the solar flux at 144. The photo above shows the 57 WSPR stations heard on 28 MHz between the time the band opened at 7:34 UTC and closed at 19:56 UTC.
Points to note....
1) Lots of spots from Australia including Tasmania :o)
2) I heard a station in Japan for the first time on WSPR on 10m! Note the Northerly path. Japan on 10m was pretty common at the peak of the last solar cycle back in 2001. Those northerly paths are still proving difficult at the moment with the flux at 144.
3) Absence of signals from Africa and South America has more to do with a lack of stations using WSPR rather than a lack of propagation.
4) The band opened to the NW coast of the US which again is a Northerly path and a good sign. It was open to the same area the previous day as well.
5) Backscatter.......every day now, I am hearing stations in the UK. A while back, I was wondering if the mode of propagation was tropo, aircraft scatter or Sporadic-E? Now I'd be almost certain that it's F2 backscatter. It seems to be remarkably consistent day after day. If the band is open then the backscatter is present. The thing is that WSPR is hearing signals that are normally buried in the noise.
These are the stations in the UK heard on the 23rd of Oct via backscatter. Most are using 5 watts. G4ILO had 2 watts into an attic dipole...
Over the last week or so, I have at times seen an odd looking signal while using WSPR on 28 MHz. It starts off about 10 Hz too low in frequency and then drifts upwards for about 30 seconds and then stays reasonably steady for the remaining 90 seconds of the WSPR two minute time period.
When I first saw this signal, I wasn't getting any decodes but eventually, it came through.....it was GW7KNF in West Wales on backscatter. I have no idea as to why his signal drifts at the start but it is unique to his signal.
Normally, I think a signal needs to drift less than 4 Hz to be decoded. Considering that at least 20% of his signal exceeds this then perhaps you don't need to hear the full two minutes of the signal to decode it? Going on the above example, it looks about 90 seconds.
While it's nice to see the stations coming through from Australia and the West coast of the US, the one that really caught my attention was ZL3PX from New Zealand. Considering that it is at the opposite end of the globe as viewed from Ireland, it's reasonably rare on 28 MHz.
But how did the signal get from New Zealand to Ireland? Short path over the North Pole? I have my doubt's. Long path over the South Pole? Or skewed path?
I got an e-mail this morning with the link to new IRTS newsletter. Looking through some of the news items, I came across a link to this video showing the new tower for the East Cork Radio Club contest station, EI7M.
This morning (~8:45 UTC), I heard NH7O in Hawaii on SSB on 28 MHz.
His signal was very weak, maybe 4/1 to 4/2 at best. He was working a pile up and it was obvious that he was getting into the UK and Ireland pretty well. I gave him a call towards the end......managed to get a EI7?? back but then he dived into the noise. I think it was probably just at the end of the opening.
But I was curious. How did the signal get from Hawaii to Ireland?
This is the short path shown above. It almost certainly wasn't short path as the band hadn't opened to the US and the North-West yet. What about long path? Did the signal travel over the South Pacific, over Antarctica and then over Africa???
Or was it a skewed path? From somewhere over the Indian Ocean? I have heard of this before whereby European stations work Japan on 50 MHz by beaming at the Indian Ocean. Not long after hearing NH7O, I could hear the Australian beacon VK8VF/B near Darwin. Earlier, I was hearing the Phillipines on WSPR so the band was certainly open to that part of the world.
Wonder what way people were beaming when they worked him? It's kind of hard for me to tell with my vertical ;o)
Some more good conditions on 28 MHz on the 17th again. Started off with WSPR station being heard in Australia and finished with ones near Los Angeles in California...
Two Australian stations were heard, VK5AKK near Adelaide and VK2FLR near Sydney.
VK5AKK was being heard or was hearing a lot of stations in Europe
In contrast, none of the stations in the UK were hearing VK2FLR. His signal went over the UK and landed in Ireland instead.
There was no shortage of backscatter? signals as well with lots of the stations in the UK being heard. GW7PEO and G4HZW were the most consistent.......
Signal to Noise of the UK stations heard on the 17th...
G4ILO.....-25dB (1 spot)
GW7PEO.....-22dB to -26dB (18 spots)
G4HZW......-20dB to -25dB (31 spots)
G4KPX.......-25dB (1 spot)
G4FRE........-23dB (1 spot)
GW3LEW......-25dB (1 spot)
G8JNJ/A.......-21dB to -26dB (5 spots)
All pretty weak signals buried in the noise. Typical of what might be expected for back scatter.
Over the last week or so, the solar flux had dropped down to around the 100 mark and there was a distinct lack of good East-West propagation. On the 16th, the flux was back up to 137 and the band really opened nicely to the USA...
There seems to have been some Sporadic-E signals from Europe as well. In fact, there seems to be plenty of weak Sp-E around most days.
Almost every day as well for the last week, I have heard WSPR signals from stations in the UK. The only pattern is that they seem to coincide with good Sp-E conditions to Europe or good F2 conditions. I would say at this stage that I am pretty sure that they are via back scatter rather than some other mode.
I came across this amazing resource recently. 73 magazine was an amateur radio publication that ran from October 1960 to September 2003. In total, there were 513 issues and they are all available now for free in PDF format.
One of the main reasons I have this blog is to act as a scratchpad for myself. If something happens that I want to make a note of, then it's a handy place to keep a record of it and if it helps someone else fix a problem that they are having then so much the better.
On the morning of the 11th of October, I was receiving a station as shown above but I was getting no decodes. Looking at the database on the WSPR website and the spots from other stations, it seemed as if the station was EA8FF, someone who I have heard and decoded over the last few days.
I switched the rig to 30m and left it listening to the WSPR signals there for about 10 minutes. No decodes. So obviously, WSPR had stopped working.
Solution.......it turned out that the sound card in the PC seemed to have crashed or at least the micropart part of it. It was a simple case of rebooting the PC and everything worked fine again.
I came across this video clip recently from the BBC about the vital part that radio amateurs played in wartime Britain by listening in to coded German traffic on the short wave bands.
The programme was broadcast in 1979 which was 33 years ago, about the same amount of time from when the events happened in WW2.
