Low Pass Filter for the 10m & 11m Bands

Another one from the archives :o). This is a design for a low pass filter for 29 MHz and would be suitable for anyone on the 28 MHz or 27 MHz bands who needs a filter to reduce harmonics. This is especially valid for anyone using a low powered radio to drive an external amplifier. e.g. Amplifying  4w to say 50-100w.

Coils...12 SWG wire. 6 turns. 8mm internal diameter. Coil length 19mm.

Capacitors...High Voltage ceramic or Mica. 110pf Cap is 100pf and 10pf in parallel.

A suitable enclosure might be a diecast box with the filter built on copper clad board. Note the screen which can be made from the pcb material as well. If you can live with a slightly lower performance in terms of filtering, you can omit the internal screens but make sure you put it in a metal box.

Hands free morse code contact :o)

This is a great video! Italian radio amateur Mauri IZ5OVP makes contact with C31CT in Andorra...but without a morse key! :o))



For those of you who can't read morse, it goes...

IZ5OVP gives his call sign IZ5OVP in morse
C31CT replies with IZ5OVP IZ5OVP 599
IZ5OVP replies with R R 599 BK
C31CT concludes the contact with R TU

molto bene

A quick look at network radios...

What is radio? As time goes by, the fine line between what can be called 'radio' and what is the internet is becoming increasing blurred.

I was on the 70cms band today using the Echolink gateway about 10 miles to the north in Watergrasshill and I spoke to Brian GM7JDS in Scotland who was using an Inrico TM-7...a so called 'Network Radio'.

A network radio is essentially a mobile phone that is made to look and behave like a radio. It can have the same appearance and some like the Inrico TM-7 have a traditional microphone which might be found on a mobile rig. It uses the Android operating system, behaves like any smartphone and can be used through wi-fi as well.

But is it 'radio' as opposed to 'a radio'? Is it 'radio' if someone at the other end is actually using a real radio with RF going out over the airwaves? What if someone is using say a DMR radio into a local hotspot in their own house, is that any more 'real radio' than this?

At first glance, a network radio isn't a radio... or at least not a traditional radio. But if it allows you access to various repeaters around the world, is it not just a remote access for a radio? If it looks like a radio and behaves like a radio, is it a radio? Many people will have different opinions.

Some of the purists may well dismiss this as not real radio but it could be the perfect solution for someone with antenna restrictions or living in an apartment complex.

From my own point of view, anything that results in some activity on an amateur band somewhere can only be a positive thing.

There is an explanation on network radios below...

Proposal to establish EI VHF Activity Nights

Proposal : Establish EI VHF Activity Nights

17th March 2018 : At present, the activity level on the VHF and UHF amateur bands is very low, possibly the lowest ever. It doesn’t help matters when the few radio amateurs that are active are spread across different bands and modes and are on air at different times.

The suggestion is that VHF activity nights should be established on Tuesday evenings. The RSGB hold VHF/UHF contests on certain Tuesday nights and the proposed schedule would tie in with those.

The schedule would be as follows...

First Tues of the month... 2m (Aligns with the UK)
Second Tues of the month... 70cms (Aligns with the UK)
Third Tues of the month... 6m & 4m
Fourth Tues of the month... Digital - Fusion / DMR / D-Star

Each activity period would be from 7 to 10pm. It's up to individuals to do what they want to do. SSB / FM simplex / repeaters. Local rag chew or try to see how far they can get.

The plan is to start it in Cork in April of 2018 and to try to encourage other areas to take part as well. I have asked the IRTS VHF manager to help publicise it on their website and newsletter.

Update : 3rd May 2018... The banner for the activity night is now up on the IRTS website.

Talk by K1JT on the latest digital weak signal modes

I came across this very interesting talk by Joe Taylor K1JT on the latest weak signal digital modes and it can be seen below. It's over an hour long and it gives a good overview of the status of the various weak signal modes in use at the moment (March 2018) on HF and VHF.



Unless you are actively using these modes, it can be hard to keep up with all the changes so I found the video very useful.

One of the interesting slides used in the talk is shown below...

The data for this chart is from all the logs updated to the CLUBLOG website in 2017. It shows how the new FT8 mode has really exploded since it was released and how it has replaced the older JT65 and JT9 modes.

It's also interesting to see how CW is still doing reasonably well and is ahead of phone! Not sure why the second half of the year is lower than the first half though?

Daytime band scan on Medium Wave using basic domestic radios...March 2018

After a recent chat with Willie EI7CGB about Medium Wave reception, I did a daytime band scan to see what could be heard on the band using just basic domestic radios. I used two radios....

Silvercrest KH2030...The first one is a Silvercrest radio which I picked up in Lidl a good few years back. I think at the time, it was only about €18 and it's performance can be at best be described as mediocre. It's fine for listening to local stations on FM but on AM, the sensitivity is poor. At night, it can pull in the strong European signals but it's not very good for weak signals. It does however have a digital readout to show what frequency it is on.

Sony CFS-W360L... The larger radio is an old model which covers FM, Medium Wave and Long Wave. Considering its size, it probably has a bigger internal ferrite rod aerial for Medium Wave than the Silvercrest and as a result is better at hearing weak signals. The tuning dial however is analogue but that wasn't too much of a problem when there are only a small number of signals to hear during the daylight hours.

The tests were done in the middle of the day when only ground wave signals would be heard. This is what was heard.

Freq KHz Station Distance (kms) Pwr (KW) Location Notes
549 Spirit Radio 280 25 Carrickroe, Monaghan Nothing on Silvercrest. Very noisy on Sony. Positive ID due to local signal on VHF.
630 BBC Radio Cornwall 280 2 Lanner, Redruth, Cornwall Noisy on the Silvercrest. OK to ID. A good bit better on the Sony. Noisy signal.
657 BBC Radio Cornwall 300 0.5 Bodmin, Cornwall Very weak on Silvercrest. Strong enough to ID on Sony but difficult to make out what is being said. Very noisy on Sony.
693 BBC Radio 5 Live 370 50 Start Point, Plymouth, Dorset Assume it's Start Point S coast of Devon. Noisy on Silvercrest. Reasonable but noisy on Sony.
756 BBC Radio 4 R3-4 2 Lanner, Redruth, Cornwall Noisy on Silvercrest. Reasonable but noisy on Sony.
801 BBC Radio Devon 300 2 Barnstable, Devon Noisy on Silvercrest. Reasonable but noisy on Sony.
882 BBC Radio Wales 470 100 Washford, Somerset, England Noisy on Silvercrest. Reasonable on Sony. Seems to be one of the strongest signals.
909 BBC Radio 5 Live 380 50 Clevedon, Somerset Noisy on Silvercrest. Reasonable but noisy on Sony.
990 BBC Radio 5 Live 300 1 Tywyn, near Aberstwyth, W Wales Hardly anything on Silvercrest. A very noisy and weak signal on the Sony.
1089 Talk Sport R2-3 2 Washford or Redruth??? Noisy on the Silvercrest. OK to ID. A good bit better on the Sony. Noisy signal.
1215 Absolute Radio 470 100 Washford, Somerset, England Noisy on Silvercrest. Reasonable but noisy on Sony.

Notes...
1) A total of 11 signals were heard. Roughly 7 of them were strong enough to listen to but with a good bit of noise. The other 4 were weak.

2) The 657 KHz signal from the 0.5kw BBC Radio Cornwall transmitter at Bodmin was about the same level as the 25kw Spirit Radio transmitter up in Co.Monaghan on 549KHz. Considering that both are roughly the same distance from here, it just goes to show the difference a sea path makes even though I am still about 20kms inland.

3) I repeated the test on several days at about the same time, the results were the same. These are the basic 11 signals that I can hear from my house.

The equipment used was very basic and would be pretty typical of what most people would have. It does however set a useful base line on which to judge future tests and improvements.

Donations for the Southern Ireland Repeater Network

The Southern Ireland Repeater Group maintain an impressive repeater network in the south of Ireland. They have no fewer than 7 voice repeaters scatted across the 2 metre and 70cms bands as well as two digital repeaters in Waterford.

While VHF and UHF activity remains at a low level, this network is largely responsible for much of the activity on the higher bands.

I noticed recently that they have added a donate facility on their website to help maintain the network. Have a look if you wish to contribute.... http://sirnrepeaters.blogspot.ie/

Hearing the Mt.Leinster 70cms repeater at 135kms on a handheld

While I was updating the code plug for my TYT MD-380 dual mode handheld, I decided to add the Mt.Leinster repeater EI7MLR on 430.950 MHz. Initially, I thought it might be interesting to see if I could hear it under lift conditions. Little did I realise that I can actually hear it all the time with the half-wave whip on the handheld just sitting next to an east facing window.

Mt.Leinster is 135kms or 84 miles from my location, quite a distance for a UHF signal. I have heard the repeater before on my main rig using a home made colinear in the attic but only under lift conditions.

The signal I am getting on the handheld is under flat conditions and it's steady... about a constant 4/1. Pretty amazing considering the distance.

The profile of the path is interesting...

Right in the middle of the path is the Comeragh Mountains at about 750m above sea level (asl). I can see these mountains from my house 40 miles away on a clear day and obviously the path from Mt.Leinster at about 780m asl to the Comeraghs is line of sight as well.

It does raise some interesting points.....

1) I tried using the handheld in the attic and I seem to hear Mt.Leinster just as well in the attic as I do at the upstairs window. I would have expected that the roof tiles would have attenuated the UHF signal more.

2) I am not hearing Mt.Leinster on my main rig with the home brew colinear in the attic. I think it might be worth trying to put up another 70cms antenna in the attic? Perhaps the colinear isn't working as well as I thought.

3) In the past, I would have considered any type of mountains as a bit of a show stopper. I found out a long time ago that if the mountains are far enough away, they are less of a problem on VHF and UHF.

80 year old US radio amateur rescued from 20ft tower

It sounded a bit like an April Fools joke but this headline is doing the rounds at the moment. An 80-year old radio amateur in the USA had to be rescued from the top of a tower which was a mighty 6 metres high. Apparently the trouble started when his shoe got stuck.

As you can see from the photo, there was no shortage of firefighters. Must have been a slow day in Edgartown.

Full story HERE

Snapshot of DMR activity in EI - 10th March 2018

After a few contacts earlier today on digital radio (DMR), I began to wonder what the DMR activity levels in Ireland was like among EI calls. After a small bit of digging, I came up with some stats which are current as of the 10th of March 2018.

Some stats...

1) 108 DMR numbers...There are 108 registered DMR numbers issued to EI calls. Even though number 272109 was issued, number 272008 is missing...so that's 108 in total.

2) 100 Individuals (incl 3 clubs)... Eight individuals have two DMR numbers a) EI9IL/EI1UN b) EI3JE c) EI4GJB d) EI4KN e) EI5CA f) EI7IG g) EI8EJB and h) EI9ED. So that makes 108 - 8 = 100 individuals with registered DMR numbers. (Three are clubs but I'll count those as individuals).

3) 46% Heard... Out of the 100 individuals registered for DMR, only 46 have been heard. (49 - 3 duplicates from EI3JE, EI4KN and EI7IG). If that's correct then that means 46% of the those that have registered a DMR number have actually activated it.

4) 41 active in 2018...Of the 46 heard, a total of 41 of these were heard in the first 10 weeks of 2018. That probably represents the current number of EI calls actually active at present on this digital mode.

5) Distribution of activity... Of the 41 heard in the first ten weeks of 2018, this is where the majority were heard last...(as of the 10th of March 2018)...
...a) 21 heard on MMDVM individual hotspots.
...b) 7 heard on EI7WCD in Tramore near Waterford City.
...c) 7 heard on EI7CDD in West Waterford.
...d) 2 heard on EI2GCD in Galway City.

6) Registrations by County... If we count the club calls and account for those with two DMR numbers, this is the breakdown by county (3 and more)...

It breaks down as Cork 14, Galway 13, Waterford 8, Limerick 8, Dublin 6, Louth 6, Clare 5, Mayo 5, Wexford 4, Donegal 3, Tipperary 3, Kerry 3 and Kildare 3.

7) DMR Registrations by Quarter... The chart below shows the total number of registered DMR users in Ireland (EI) at the end of 2017.

It's worth pointing out that the stats above don't show the large pocket of activity in Northern Ireland as well (GI).

Taken all together, there are three pockets of activity in Ireland...in the south-east near Waterford & East Cork, near Galway City and in the north-east near Belfast.

It's amazing there is no real activity yet from near Dublin? Why?

Links...
1) EI registered DMR numbers

Line of Sight to the DMR repeater EI7CDD

After a spell of four years off the radio, I got on air again in late 2016. Once I came back, I found out there were some new developments in the world of digital radio with D-Star, Yaesu System Fusion and DMR. I read up on these but at that stage at the start of 2017, there were no digital repeaters anywhere near me in Cork.

After another short spell off the radio from May to December 2017, I found out in January of 2018 that a new digital repeater with the call sign EI7CDD had been installed in West Waterford in September of 2017.

The new repeater was located on a 300m high hill called Carronadavderg in West Waterford which just so happens to be line of sight to my house!

Carronadavderg is high enough so that it is visible for me over the hills to the north of Killeagh. The repeater is 45kms / 28 miles away.

On any sort of clear day, I can see Carronadavderg on the horizon. This is a photo I took today with a small telephoto lens on the camera. The golf course in the foreground is about 2-3kms away.

The white below the summit of Carronadavderg is a layer of snow while the darker summit is covered in trees.

On closer inspection, some white microwave dishes can be barely seen on the summit when the sun was shining there. The houses in this view are some 25kms distant.

The view was a little better when the dark masts were contrasted against a bright background. I can pick out six masts in total...three large ones and three small.

Pretty amazing what the camera could pick up from 45kms away!

The main thing of course is that it is line of sight from here which allows me to access the DMR repeater with 1w from a TYT MD-380 handheld with a whip antenna.

When I check the Last Heard list for EI7CDD, I seem to have a signal of S4-6 when I stand next to a window here in the house so I can get into the DMR system fine.

IRTS Membership Stats...End of Dec 2017

In the most recent newsletter from the Irish Radio Transmitters Society (IRTS), they stated that there was 927 members in the society at the end of 2017. I had a look at the previous membership levels and I put together this chart...

As the chart shows, there was four years of decline from 2009 to 2013 but it has leveled out since then. While the chart may look pretty dramatic, the range from the highest to lowest point is in the region of 8.5% so it's not huge. In the last decade (2008 to 2017), the IRTS membership has declined by 5.8%.

Another interesting stat from the newsletter is that there was 1729 EI call signs at the end of 2017. Back at the end of the year 2000, it was 1726...almost identical. I suspect that a lot of people would have expected the number of EI call signs to have dropped since the start of the new millennium but that doesn't seem to be the case.

One worrying aspect is that the number of EI calls that are members of the IRTS is dropping. The chart below shows that 44.9% of all EI callsigns are members of the IRTS as of the end of 2017.

Considering that the IRTS membership has dropped since the year 2000 and the number of licences is largely the same, the overall percentage of EI calls who are members must have dropped.

As it says on the IRTS website..."IRTS is the national society for radio amateurs and experimenters in Ireland.  Its purpose is to promote the study of radio communications, to encourage radio experimentation and to provide services to its members."

It would be nice if more people with licences supported what is an organisation run by volunteers on behalf of its member. €30 per annum is a very modest fee.

Links...
1) IRTS website

High Tech Morse Code Safety Boots!

There was a news item on the BBC news website today about some new safety boots that use morse code for signalling purposes!

According to the manufacturers..."The shoes holder can “press” this “button” with his toes to start a sequence (composed of 2 symbols: “short” or “long”, an alphabet derived from MORSE code). This differs from other smart PPE that do not allow interactions with the device without using hands. Right and left vibrating motors, as well as a 90dB buzzer, allow the shoes to communicate with the holder using short and long vibration or beeps too. For instance, this system allows holder to acknowledge when he receives a message to leave immediately an area. Or he can send a “MAY DAY” message to alert his employer or colleagues. To handle extreme situations (such as broken leg), a second external membrane is also available by hand."

Links...
1) BBC News item
2) Manufacturers website

New 70cms repeater in West Wales...

Over the weekend, I was using EchoLink and I came across a new Welsh repeater there.... GB3UP-R in Fishguard on the west coast of Wales.

I had a chat with the repeater keeper Simon GW6TKK and it turns out that the repeater has been up and running since August 2017.

Here are the basic specs...

Keeper/NoV holder - Simon GW6TKK
Channel - RU73  input Frequency -  438.5125 MHz  Output frequency 430.9125 MHz
Access - CTCSS Tone F 94.8 Hz
Echolink Node GB3UP-R

The repeater is located in a domestic house about 300ft asl on the south side of the town of Fishguard and is heavily screened by hills to the south and east. This is shown in the coverage map which is pretty small over land areas but would be much bigger over the Irish Sea if it was shown. It's very likely that it can be worked from Ireland under lift conditions so it might making a note of it.

The repeater website is http://sparks.btck.co.uk/FishguardRepeater

Cork Radio Club in the SSB Field Day Contest...Sept 1999

I came across this video by accident while I was looking for something else. Despite the fact it is over 18 years ago, field days today are still pretty much the same.

EI DMR Registrations...

A few weeks back, I got a registration number for using DMR (Digital Mobile Radio). Considering DMR has its roots in the commercial world, I think that this will become the de facto standard for digital radio on the VHF amateur bands in the future...as opposed to D-Star or Fusion.

I was curious to see how many EI stations have registered to do and I put together the chart above. The 2017 peak coincided with articles in the IRTS newsletter.

The chart below shows the total number of DMR registrations for EI calls at the end of each quarter up until the end of 2017...

As of the 9th of February 2018, there are 106 EI calls registered on DMR. Needless to say, not all of them are active or may even have equipment but it does show a growing interest in this digital mode.

Update 9th March 2018 : Using the 'Heard Users' function, 47 of the 108 registered users have been heard using DMR. That's roughly 44%.

Free PDF articles from the UK Microwave Group

This might be of interest to those who operate on the microwave bands. Backscatter is a compendium of the best technical articles that have been in Scatterpoint, the UK Microwave Group newsletter over the period 1999 to 2006.

The original publication in 2008 was an A5 size book of 445 pages and is an excellent reference with many articles on all aspects of microwaves.

It is now freely available as pdf chapters via the link below:- http://www.microwavers.org/?backscatter.htm

Free HackSpace Magazines...

This might be of interest to anyone using Rasberry Pi or Arduino boards. HackSpace are offering their magazines for free via this website... https://hackspace.raspberrypi.org/issues

There are plenty of radio related projects out there that have these systems at their core.

EI-GI Packet Map for 1994

I recently came across this old map of the various packet nodes in Ireland back in 1994 (Click on the image to see the full size version).

In today's world of smartphones and tablets, it's easy to forget about what a big deal packet radio was back then. In 1994, most people weren't on the Internet and the only source of information was via email at work or via magazines and books.

The killer 'app' at the time if it could be called that, was the DX-Cluster. When it was working properly, it allowed people to see for the first time what was happening on the bands and what others were hearing.

From what I remember, I started using packet radio back in the early 90's with an old DIGITAL computer terminal, a PK-88 TNC and a really old PYE 2m radio.

1994 may well have marked the peak of packet radio in Ireland. A few years later as more people got access to the Internet, the packet radio network went into decline. The 1200 bits per second speed back then seemed fine at the time but it was arcane compared to say a dial up modem let alone the megabit fibre connections of today.

Today, packet is used mainly for APRS (Automatic Packet/Position Reporting System) where stations sent out an identification bursts every few minutes. A map of Irish stations on APRS can be seen HERE.

Certificate for the Dutch PACC Contest

Slowly getting back on air again after a long break of about 9 months. In the meantime, a certificate arrived in the post for the PACC contest that I had entered last February.