Over the last few weeks, I have been reading up on the various digital radios on the VHF bands. It would seem as if there are three potential modes which could be a replacement for analogue FM.
1) Icom D-Star, 2) DPMR and 3) Yaesu System Fusion
While the digital radio network in the UK seems to be pretty well developed, it is still in its infancy in EI.
A recent news item from the IRTS outlined how the the Yaesu System Fusion was being introduced in Donegal and Limerick.
A key fact is that the Yaesu DR-1X repeater controller will work on both analogue FM and on the Yaesu C4FM digital system. This means that at worst, it will work away as an FM repeater even if no-one uses the digital system. It will receive digital signals and convert them to FM on the o/p so that everyone can hear them. e.g. Digital in, FM out. It can also relay whatever is on the input...i.e. FM in, FM out OR digital in, digital out.
It was mentioned in the news item that some people in the Limerick region have bought the following Yaesu radios...
There are some obvious issues with introducing this new system in EI...
1) As you can see, they're not cheap. Someone can buy an ordinary analogue FM rig for a lot less. A cheap Chinese FM handheld can be purchased for less than €50.
2) The level of activity on the existing FM network is pretty low. The Limerick repeater has very little traffic on it as it is so it's hard to justify buying an expensive radio.
It will be interesting to see how things develop. I suspect though that in Ireland, DPMR may well become the system of choice for those that want to experiment with digital as cheaper radios come on the market.
This video explains what the Yaesu Fusion System is all about....
I have been scanning and listening on 145MHz for most of November 2016 so I now have a reasonable idea as to what the level of activity on the band is like. As expected, the level of local activity is very low and is mainly confined to mobile stations calling through the various repeaters.
The only real activity period is after the IRTS news broadcasts on Monday and Tuesday evenings.
This is a map of the repeaters that I have heard on 145 MHz under flat conditions...
These are the frequencies I have heard most activity on while listening to 145 MHz FM. The set up was pretty modest with just a home made half wave vertical antenna. The signals in Purple are those heard under lift conditions.
Freq.Station
145.400 ... Used as a net frequency near Waterford city
145.450 ... Used as a net frequency in South Tipperary
145.475 ... Packet type signals from the Chinese Satellite Kaituo 1B. Norad ID 40912.
145.525 ... Used as a net frequency in Wexford 145.600... FM repeater. GB3WR nr Bristol. IO81PH. CTCSS F 94.8Hz. 145.6325... FM repeater. GB3DN. North Devon repeater. IO70UW. CTCSS 77Hz.
145.650 ... FM repeater. EI2DBR. Devil's Bit Repeater, Tipperary. IO62BU. Southern Ireland Repeater Network.
145.675 ... FM repeater. EI2HHR. Helvick Head Repeater. IO62EC. Southern Ireland Repeater Network. 145.675... FM repeater. EI2CCR. Clermont Carn Repeater, Co.Louth. IO64UB.
145.675 ... SSB on downlink from transponder on Chinese satellite XW-2A. Norad ID 40903. 145.6875... Digital repeater. No positive ID. Might be GB3WE? Weston Super Mare. IO81MH. 145.700... FM repeater. EI2TKR. Truskmore Repeater. Sligo. IO54TI. CTCSS 77 Hz. 145.700... FM repeater. GB3AR. Carmarthen Repeater. IO73VC. 110.9Hz.
145.725 ... FM repeater. EI2TAG. Tountinna, Tipperary. Limerick repeater. IO52TU.
145.725 ... Beacon on Chinese satellite XW-2B. Norad ID 40911. 145.725... FM repeater. GB3NC. North Cornwall repeater nr St.Austell. IO70OJ. CTCSS 77Hz.
145.750 ... FM repeater. EI2MGR. Mullaghanish, Co.Cork. IO51KX. 145.7625... FM repeater. GB3PL. East Cornwall. IO70VM. CTCSS 77Hz. ID is 'GB3PL Amateur Radio Repeater'. 145.775... FM repeater. GB3WW. West Wales repeater. IO81CP. CTCSS F 94.8 Hz. 145.775... FM repeater. GB3WT. West Tyrone. IO64JQ. Nr Omagh. CTCSS 110.9Hz.
While this list is unique to my location, it should give a general guide as to what can be heard if you are living near Cork. You may well hear other repeaters but this is a good list to start with and it's a guide on where to listen.
This post is for my own benefit as I want to put the CTCSS codes somewhere online that's easy to find.
CTCSS.....What is it? This is the description from Wikipedia...."In telecommunications, Continuous Tone-Coded Squelch System or CTCSS is a circuit that is used to reduce the annoyance of listening to other users on a shared two-way radio communications channel."
In more practical terms, it is a tone that you can't hear that is added to your transmission so that you can access a distant repeater. If you don't use the CTCSS tone then the repeater will ignore you. It should mean in theory that under lift conditions, you can open up one specific repeater as opposed to several at the same time.
The letters are used in the UK to ID the CTCSS tone required to access some repeaters.
This morning, I heard the GB3WR repeater on 145.600 MHz. It was pretty weak and was 4/1 at best but the CW id was clearly audible.
At just under 400kms, it is the furthest signal that I have heard this month. Considering I was using a home made vertical half-wave in the attic, I presume it would have been much stronger with say a beam outside.
Still though, it was interesting to hear a signal from that distance. The map above shows the locations and the key is of course the sea path.
Listening to the conversation this morning, the repeater antenna seems to be on a 200ft mast and the repeater site is at 1000ft above sea level on the Mendip Hills to the South-West of Bristol.
Update 12:45pm: The repeater is still there in the noise. ID on CW is "GB3WR" and sometimes "GB3WR F". The repeater uses a CTCSS access tone of 94.8Hz which is tone 10 or 'F'. I presume the F in the ID is to tell people what the access tone is. Update 2:45pm: GB3NC in Cornwall (298kms) was there as well at S'3'. CTCSS code 'C' which is 77Hz. GB3CM on 433.200MHz is in there as well. Update 9:30pm: Heard GB3WW near Swansea on 145.775MHz. Distance is 316kms. It gave out 'F' after the callsign ID which again ties in with the CTCSS code.
I've been scanning and listening on a pretty regular basis on 145 MHz FM for the last two weeks so I am getting a good feel of what I can hear with the home brew Slim Jim vertical in the attic. On Saturday the 26th of Nov 2016, there was a reasonable lift and the following were heard on 145 MHz...
With the exception of MW0DEW, the rest were repeaters. Obviously most are on hills but it was interesting to see what could be heard with my current antenna. None were that strong but I could hear the CW identification every so often.
MW0DEW was a Welsh station I worked on 145.475MHz. He was using 30w into a vertical antenna just 4m above ground level. The distance was just short of 300kms, a nice distance for an indoor antenna.
Over the years, I have collected many old magazine articles and it seems to be a waste to have them buried away in a folder. This one is for a 3/8 wave ground plane antenna for 28 MHz and hopefully it might encourage someone to experiment and build one.
The principle is pretty easy. A normal dipole in free space normally has a 72 Ohm feed point impedance. A quarter wave ground plane is half this...about 36 Ohms.
By extending the antenna from a quarter wave to a three-eight wave, the maximum current point moves from the base to further up the radiating element. This has the effect of lowering the angle of radiation which is a plus.
The longer three-eight wave antenna now has a reactive feed point (inductive) as it's too long. This is tuned out with a series capacitor and it should be able to get close to 50 Ohms.
This antenna would suit someone who can only put up a quarter wave ground plane for 10 metres and wants better performance.
The article from the March 1983 edition of Short Wave Magazine is shown below...
25th Nov 2016...There seems to be a reasonable lift on the VHF bands today as there is a high pressure weather system over the country. I noticed it first late last night when I heard the West Tyrone repeater GB3WT in the noise on 145.775 MHz.
This morning, the Limerick repeater on 145.725 MHz which is normally S3 on my indoor antenna was up to S8 and I was able to have a QSO with MM0RJJ and MI0ADX on it with just 5 watts.
Looking North from here this morning, I could see the inversion layer with the high pressure keeping the air trapped near the ground. It can be seen as that dark band on the horizon which is usually slightly pink/purple in colour and is in marked contrast to the clear air above....a classic sign of air trapped near the surface.
This inversion layer means good VHF conditions and it ties in with this tropo propagation map for this morning...
The biggest suprise this morning was hearing the GB3CM repeater in Wales on 70cms. It was up to s'8' at times and that is with a home made colinear antenna in the attic. The distance is about 286 kms, well in excess of the usual range for that repeater.
GB3CM
70cm (FM) UHF Repeater
94.8Hz CTCSS tone and the 'time out' is set to three and a half minutes
Operating on 433.200MHz output 434.800MHz input
Power 20w
As I don't have the 70cms rig programmed for that CTCSS, I didn't try to work through it. I'll have to dig out the manual again :o)
Additional info... GB3CM...Website for the GB3CM repeater.
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?
