The IRTS Weekend Hosted by the Galway VHF Group 2018

It was very much by accident that the Galway hosted this, the 86th Annual General Meeting Weekend of the IRTS. It was to be held in Cork but they decided against it and passed it over. The Galway VHF Group put their name forward at the last minute following a brief call to the Galway Bay Hotel. This is, in fact, the 4th IRTS Function organised by Steve EI5DD. The first was in 1985 in the Warwick Hotel, Galway (sadly the Warwick closed in 2008), the Second was 1992 in  the Royal Hoey Hotel, Athlone, the Third in the Galway Bay Hotel 2014 and this one in the Galway Bay Hotel for 2018. The service and facilities were excellent as on the previous occasion.

On Saturday the 14th at 2pm a series of talks were given on the Following topics. "Getting Started with Digital Radio" by Steve Wright, "The 7Q7EI Dxpedition", by Enda Broderick EI2II, "The FT8 Digital Mode" by Keith Wallace EI5KO, and "Having fun in Space" by Graham Shirville, G3VZV. The talks were of 45 minutes duration and saw a good attendance and great interest. Special thanks to all of the lectures who presented their specialist subjects.

 Steve EI5DD lecturing on DMR

 Enda EI2II and Pat O'Connor EI9HX lecturing on the 7Q7EI  Dxpedition

 Keith Wallace EI5KO lecturing on the FT8 Digital Mode

 Graham Shirville G3VZV lecturing on Satellite Operation

The Annual Dinner took place at 7:30 pm and this was attended by 69 people. The food and service was excellent. It was a shame that a number had booked tickets and didn't show which placed a burden on our group given that we had to book for 75 and naturally the Hotel held us to this number.

Steve, EI5DD, welcoming the guests

Steve & Hilary Wright

John Anderson, MI0AAZ,  and Mary 

Joe Fadden, EI3IX

Tom Rea, EI2GP, and Loretta
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A view of the function room

IRTS President Gerry Gervin EI8CC

A really great night was enjoyed by all following the excellent meal. A quick draw for spot prizes took place which added to the fun of the evening.
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The following day was devoted to the Rally and AGM so it was an early start to ensure that the tables were marked and ready for their traders. One had to ensure that nobody encroached on the allocation for a neighbouring trader.
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Early Morning and the traders just arriving. Mike EI0CL was the first in and had a huge stand 

 Joe EI3IX at the Mayo VHF Group Stand

Steve EI5DD and John Anderson MI0AAZ at the Brandmeister Digital Radio Stand

Mark Bannon and John Anderson in deep discussion about DMR Repeaters
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 Raymond Long - Long Communications

Philip Hosey and the Region 8 RSGB team manning the RSGB stand

Jimmy Kelly, running the Mayo Radio Experimenters Club Stand

 

Jimmy Kelly and Padraig Baynes 

Two rogues Mike EI0CL and Steve EI5DD
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This and the next 7 Pictures show a sample of Mike, EI0CL's, goodies

Peter Green EI2IU

  Arek, EI9GWB, selling customised shack accesssories see items below

A handmade Shack Sign made for EI5DD

Sean with his 2nd hand commercial radio products

 The IRTS Stand manned by Pat Fitzpatrick

 

Silent Key Equipment at the end of the IRTS Stand

During the Rally CW tests were run by Dave Moore, EI4BZ, and there were two applicants who passed with ease. The Annual General Meeting of the IRTS took place at 2pm and the rally closed shortly after this time. It would be appropriate to thank all of the traders and Radio Clubs who were kind enough to attend and make this rally so successful. There was an excellent turn out for this rally. The proceeds of the weekend will be going towards our new DMR Repeater, antenna and feeders.

 The AGM in full swing

 John Brown EI7FAB receiving his trophy for the 1296 MHz contest

Steve EI5DD receiving the Kevin Freeney Trophy for Experimentation and Innovation. This was for time devoted to the promotion of Digital Radio both locally and Nationally.

This was a really enjoyable weekend and we thank the Galway Bay Hotel for their excellent service through out he weekend and during the organisation of the event. Special thanks to all those who attended the lectures, the AGM dinner and the large crowd from far and wide who attended the rally. We also thank the traders who put on a great show and contributed to the huge success of the Rally.

We thank Joe EI3IX and Joe EI7GY for their pictures shown above.

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New Product - Inrico TM-7 - Is It Real Radio?

The Inrico TM-7, a best seller network radio and is the first mobile network Radio. Great for amateur radio use with the new IRN platform, for Zello, Team Speak 3 and Echolink via 3G or WiFi. And it works as WiFi hotspot too! This network radio is fully compatible with the International Radio Network (IRN) and with the new Echolink for Android.  

What follows is not an APRIL FOOL JOKE.

  

Wot? - It looks a like a Motorola!

What is in the box?

The Inrico TM-7 comes complete with Microphone, Power Lead and GPS antenna. On switch on, it is blatantly obvious that the operating system is that of an Android Phone. As an optional extra, one can obtain a small mag mounted Cellular Antenna. It should be noted that there is a provision to insert a cellular network sim card into the underside of the radio. The actual data useage is not that heavy.

It is necessary to import a few apps from the Google Play Store such as APRS Droid, Teamspeak 3 and Echolink for Android and perhaps even Zello. Provided that you have registered with Echolink, it is a case of entering your callsign and password and away you go on Echolink. Absolutely no problem as it will work first time.

APRS Droid requires a small payment for the app followed by the entry of a registration key and the app will fire up very quickly once the GPs antenna is connected to the "Radio". There is no problem with any part of the route. Operation on APRS via 2 metres would often see parts of the route missing due to poor coverage. Cellular towers cover pretty much everywhere nowadays.

Teamspeak 3 is required to link into other Amateur Radio Applications. After download, it is necessary to join the International Radio Network to obtain the privilege key to allow access to the amateur radio transmitting areas. A simple process, without the necessity to upload the license. After filling out  the necessary online forms, the IRN team check QRZ.com, and other areas, to ensure that your details are correct before issuing the key. I stress here that unless you can prove that you are a radio amateur, you will not get the key.

 

There are a number of zones in the IRN server which cater for Amateur Radio. The most popular is the UK Hub and one may find repeaters and other Amateur Groups linked together. To select a particular station, or net, one uses the touch screen. This is not too easy as my fingers are a bit large for the small display, however, the stylus for the Android tablet does come in handy. 

Operating this "Radio" is no different to the operation of any other VHF/UHF black box radio. Just press the PTT and talk. In fairness, this all happens via the data connection on the WiFi or 4G Network. The audio quality is excellent on both Echolink and on the networks available via Teamspeak 3 and the International Radio Network. The UK Hub is connected to Echolink, DMR, D-Star, Wires-X and a couple of Repeaters. Searching through other areas, there are nets from the UK, Australia, the States, and South Africa to name a few. Temporary groups may be set up for private chats amongst individual hams. There is always activity on this device from many parts of the world.

Zello can be added and it is possible to chat to non-radio hams and for personal use. This would not enable connection into the zones where amateur radio operation takes place.

The RT4 4G /LTE is a handheld radio that would pair nicely with this device and an added bonus is that it doubles as a mobile phone. It provides all the functions of the TM-7 but you can make mobile phone calls as well. It is chunky and has an antenna sticking out of the top. The antenna has nothing to do with phone or communications. It is the GPS antenna.

Is it Real Radio?

The debate can go on for ever. Looking back in time, it could be said by CW operators that the new AM mode was not real radio. The introduction of SSB caused more discontent and, to cap it all, the introduction of FM was the end of the world. I remember saying that FM would never catch on in the 1960s as there were very few using it - a bit like comments about digital radio today. FM resulted in the introduction of Repeaters and then it was really necessary to hold up the crucifix. In time, this sacrilege soon became acceptable and the norm. One should not forget that, as time progressed, many Analog repeaters were linked via IRLP and Echolink and the first generation of Yaesu's Wires system. 

Whilst discussing Digital Radio, at an IRTS Lecture in Dundalk, two Radio Amateurs became quite irate and irrational, saying that Digital Radio would never be encouraged in their area - end of story. Famous last words me thinks! Their part of the country now has the highest uptake of Digital Radio according to the DMR listings and I am sure that they will have a DMR repeater in their City sooner or later. The circle turns!

A well seasoned HF contest operator would throw forty fits at the thought of an internet connection to a major HF radio installation in a beautifully RF quiet area. I am sure that WiFi radio would provoke instantaneous Hari Kari in his case.

Looking at another angle, one has to see the way commercial broadcasting has developed. Not only is it Digital but almost all commercial broadcasters stream via the internet and can be picked up on WiFi radios or mobile phones with the correct app. Nobody bats an eyelid about this and it is an excellent opportunity to listen to stations in HiFi quality from locations all over the world.

Commercial two way radio is very much influenced and controlled via the internet whether it be by DMR or TETRA operation. Security companies would be lost without video feeds from remote sites via the internet. Taxi companies are a prime user of 4G internet communications.

Yes things are changing, and we, as radio amateurs, will have to adapt, adopt and improve as this is what we do. DMR, D-Star, Yaesu Fusion, P25 and NXDN all have an input and output via the internet somewhere along the line. One can transmit into a repeater or gateway in Galway and come out in Australia over another repeater. Hey - how many sit patiently waiting for DX on the HF bands. Australia is not DX on Digital Modes! A few seconds of a call will bring up an Australian station almost immediately on Digital Radio - no pile ups or poor operating here. Digital operators are gentlemen.

The formation of interlinked modes, Echolink and repeaters into a Hub has proven successful and it has enabled a number of operators who just cannot transmit on an external antenna or who are not in the range of a repeater to communicate. 

If you are not into Amateur Radio, this is the ideal system to keep in touch with family and friends all over the world via Zello or other personal talk areas not associated with the licenced operator's area. The cost is minimal.

Whatever floats the boat at the end of the day. To quote Chris, G7DDN, "Does the fact that one transmits on cellular frequencies at 800MHz, 900MHz, 1800MHz, 2100MHz or on Wi-Fi on 2.4GHz or 5GHz matter? Is there something intrinsically evil about that? Is there more virtue in using 14 MHz or 144 MHz, for example? They are just “frequencies” after all".

This article does not reflect the view of the Galway VHF Group apart from the avid texters WattsApp and mobile phone users. As they will say in the future, "You are 5 9, whats your IMEI Number - QSL"!

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Galway County 70cm Repeater EI7AKR

The Galway 70cm Repeater, EI7AKR, located at Knockroe, Abbeyknockmoy, continues to give an excellent service and coverage throughout county Galway and into adjacent counties. All of the roads leading in and out of Galway have a good strong signal from this repeater and it is possible to drive from just outside of Limerick through to Claremorris Co. Mayo with a strong signal for the majority of the journey.

Like all of the repeaters around the country, this does not seem to be very busy and if not used, there will be fewer monitoring the output. It would seem a shame that one almost has to make a phone call to another operator to get a contact on this Repeater, but, sadly this is the state of play nowadays. 

If you have equipment in the car take time to listen on 430.825 and transmit on 438.425 (+7.6 MHz)  CTCSS tones of 77 Hz are required to access the repeater. The repeater does also transmit 77 Hz CTCSS tones which will ensure that you receive no interference on channel when the repeater is not transmitting.

Do spare a thought for this repeater as it has huge potential and is just standing by for use

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Have You Tried the Worlwide Net on DMR TG 91 16:00 UTC Saturday Evenings?

The TalkGroup 91 Worldwide net takes place on TalkGroup 91 commencing at 16:00 UTC on Saturday evenings. The net commences with call-ins from the Far East and working across the continents in a westerly  direction where the last call-ins are taken from the individual States of America.

This is a great opportunity to access the activity on DMR and also to note the countries that call into the net. Naturally, the amount of call-ins from some areas will coincide with the early hours of the morning but sometimes it can be surprising that even these countries will input the the net despite the early hours in their location. 

The net controller will request the countries that he wishes to call in. The station will then give the following reply Call sign ...... , Name ...... , QTH ........ and finally the words "No Traffic" if there is no emergency or information for the net. Do not try to enter into a QSO as this is just for check-ins from each country.

When the net is finished,  the Net controller will correlate all the calls and place the table on the website at http://www.ac2he.com/ usually by 10pm at the latest. The chart below is the typical summary of the net held on Saturday afternoons.
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As illustrated, there are a wealth of participants on this Net and a good indication of interest and support around the world. Well worth a try and also an opportunity to put your area on the map.

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Galway City Multimode Digital Gateway EI2GCD

On Monday the 13th of November 2017, the Galway City Multi mode Digital Gateway was pressed into service. The Digital Gateway is fabricated from a Motorola GM350, Raspberry Pi, Arduino Due and a MMDVM modem board. See Picture below.

With assistance from John MI0AAZ on Team Viewer, the program was initially set up on the Raspberry Pi. Unfortunately, the setting of the Transmit and Receive audio levels were critical and required setting on a spectrum analyser. John McCarthy EI8JA had performed this task on his own Repeater and offered to set these critical levels for us. The Repeater was returned and a decision was taken to load the Pi-Star software on the Raspberry Pi as it was easier to manage and set up. 

At the same time Joe, EI3IX, had built a similar system for the Mayo area. It was decided that we would adopt the same Software for his Gateway. The aim was to place the two systems on air together.

Once Pi-Star was installed on both systems it was possible to mimic the settings and they both worked with a few minor problems that were easy enough to rectify.  A Skype chat between Mayo, Galway and Northern Ireland enabled final checks and the Gateways were powered within minutes of each other.

The GM350 and the Raspberry Pi booted up together with the status lights indicating that all was well.

Following tests on both Yaesu Fusion and DMR, the system appeared to be connecting to the server and stations were being heard by the system. A typical screen shot from the Pi-Star dashboard is shown below.

The dashboard was well populated in a very short space of time with DMR contacts. Yaesu Fusion was tested later and proved to be functioning well. The Brandmeister Dashboard revealed the connection was functioning properly on both DMR and Fusion.

A look at the network map showed the Gateway positioned in its corrrect location in Galway City.

The map coordinates were interpreted properly on this occasion unlike my DV Mega which was shown about a mile further east from my home location. 

Whilst there is not a huge amount to activity in Galway, this system will, at least, bring some activity to those who do go on the air and also provide an opportunity to operate whilst mobile in the car or walking with a handheld radio.

For further information about this project see the EI5DD Blog >>  click here
Further information about Digital Radio may also be found on the EI5DD Blog.

Special thanks to John Anderson MI0AAZ, John McCarthy EI8JA, and Joe EI3IX who were all involved in the set up and final testing phase of this Gateway.

Parameters and operation: Click>>>  HERE
 

Specifications of the Galway City Gateway

Call sign EI2GCD

Location Galway City

Frequency 144.8500 MHz

Time slot 2 

Colour code 1

Default DMR Talk Group TG 2722 ( Ireland Calling) 

Default Yaesu Fusion Server IE YSF Ireland

Sysop Steve EI5DD - reports welcomed >> HERE

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Specifications of the Mayo Gateway 

Call sign EI2DOD

Location 10m East of Castlebar Co. Mayo

Frequency 144.8250 MHz

Time Slot 2

Colour Code 1

Default DMR Talk Group TG 2722 (Ireland Calling)

Default Yaesu Fusion Server IE YSF Ireland 

Sysop Joe EI3IX - reports welcomed>> HERE

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Galway City DMR Repeater EI7RHD

A proposal has been made to set up a DMR repeater for the Galway area operating from a site near Circular road on the West side of the City. Our group was offered a reasonably priced Hytera 985 repeater which was really not to be refused. 

This Repeater is a Commercial system easily programmed to operate on the 70cms band. Once connected into the internet, it will network with the Brandmeister Server located in Waterford giving connectivity o a worldwide basis . The Hytera is capable of running 50 watts but we will reduce this to 30 watts as there is little point in running it to the extremes of its capabilities. 

The cavity filters are situated on the chassis. and, unlike an analog repeater, these cavities will operate quite comfortably at 30 watts without warming. As the DMR signal is 50% duty cycle, these will run and remain cool and stable. There is a facility to run an Analog signal from this repeater but this may be a conflict of interest. There is already a 70cm Analog Repeater in the City and also EI7AKR situated in a rural area to the East.

The proposed coverage from site chosen is as follows:

The antenna will be a vertical system which is a 3 x 5/8 colinear antenna giving a reasonable gain over a dipole. This plot was derived assuming 30 watts power and the antenna with a gain of 9dB. over a dipole. 

This will be the third DMR repeater to be established in Ireland and will be networked into the existing Brandmeister system. 

This Repeater will facilitate those with an interest in DMR and the development of this aspect of the hobby. The networking capabilities are endless and will ensure that any activity in Ireland will be transmitted to our area. 

To see more of the digital facilities around Ireland click here
EI7RHD Web page click >> Here

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Digital Radio

DMR Radio

With the availability of cheap handheld transceivers manufactured by the Chinese, DMR Radio has become popular amongst the amateur radio fraternity. There are a number of handhelds to chose from, ranging from Tytera, and clones such as Retevis, and Zastone.

The Zastone became a big hit when it was offered as a pack of two handheld transceivers for £108.00. This was a UHF handheld which could be easily programmed with Tytera Code Plug software. It was in fact a clone of the MD-380. The pack contained two chargers, a programming lead and a "Matrix" style earpiece/microphone. In a short period of time, the sale was over as the stock diminished overnight. At the time the Tytera was selling for £80 - £90 on other outlets such as Amazon. Most were UHF but VHF transceivers were also available but not as popular.

A new kid on the block is the Radioddity GD-77 which is a dual band VHF/UHF handheld transceiver.

Things have moved forward to the point where the Radioddity GD-77 was released at 66 Euro. There was a sale announced and the stock was sold out within 3 days. Even at a higher price of 80 Euro on Amazon, the stocks were cleared overnight.

This radio is well supported by the manufacturers via a Facebook Page. Feedback from customers and their wish lists were taken into account and appropriate Firmware upgrades follow. Not only are all of these DMR radios capable of operating in Digital Mode, but, they can also be programmed for Analogue channels. At current prices, they can easily compete with Wouxun and Baofeng handhelds.

For some time there were no mobile DMR transceivers apart from the expensive Motorola versions which sell for £365 upwards. Either VHF or UHF versions can be purchased with or without the Keypad microphone which retails for £85.00. Pictured below is a Motorola DM4600. 

These DMR sets are for Commercial use and have many additional features not normally used by radio amateurs. They are not easy to program but one has the ability to program a more basic set, it follows the same pattern. 

It was not too long before a dual-band mobile radio was marketed by TyTera in the form of the MD-9600. This operates on VHF and UHF and it is possible to program both VHF and UHF channels into this radio. It has great prospects and will be backed by regular updates by the manufacturer.

This Transceiver is almost as easy to program as the Tytera range of handhelds.

There is a little effort required to program a DMR radio but once one has the grasp of programming a code plug, life does become easier.

Link to Basic DMR Programming Tutorial >> here

A Brandmeister network has been established in Ireland and has three Talk Groups:

1) Ireland Call Channel - Talk Group 2722 -  needs to be programmed as a channel in the code plug

2) Ireland Chat Channel - Talk Group 2723 -                 -- As above --

3) YSF Ireland Channel  - Talk Group 2724                   -- As above --

The YSF Ireland Talk Group bridges DMR to Yaesu Fusion (re-transmits the audio from DMR onto Yaesu Fusion and vice versa. If one is operating DMR on this Bridge they may have QSOs with Fusion operators and vice versa.

Yaesu Fusion (C4FM)

Yaesu Fusion is probably the easiest way to get on air with a Digital Mode. The Transceiver may be taken straight out of the box an, after programming the call sign without having to read the manual. It is, however, necessary to read the manual to derive the benefits of the fusion mode. Some examples of Yaesu Fusion equipment are sown below

Yaesu has developed the Digital Wires-X Network accessible by pressing the DX button on the front of the transceiver. This is, essentially, a more up to date version of Echolink or IRLP with a superior network capability. With Wires-X, it is possible to press a button on the front of the rig to access the network and choose a room from a chosen part of the world to make a call.

The Galway VHF Group has recently given a contribution to the Galway Radio Club towards a new Yaesu Fusion Repeater which will be fitted with the Wires-X system. This should go on the air in October 2017.

The Multi-mode Digital Gateway situated on 145.850 MHz, covering DMR Fusion and D-Star, will cover Galway City and a surrounding radius of 25 miles. This will go on air in October. The Call sign will be EI2GCD.

A Yaesu Fusion Gateway, with similar coverage, will be going on air in October. The Callsign will be EI2SHD and the frequency will be 144.8125 MHz.

All of the Galway VHF Group are currently active on Yaesu Fusion and some are active on DMR. The Galway VHF Group would be delighted to assist anyone who wishes to enter into the field of Digital Communications.

If you wish to discover more about this aspect of the Hobby contact Steve EI5DD at wrights1@eircom.net

More information may be obtained >> here

Considerations for a Digital Radio System in Galway may be obtained >> here 

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Installing the 70cms Repeater at Knockroe

A meeting prior to the installation ensured that all parts had been purchased and also who currently had them in their possession. The last item required was the 20ft pole. John looked after the purchase and delivery of the pole to the site.

Gerry took charge of the guying equipment and all of the necessary parts were handed to him. Andrew took charge of the fencing materials and the parts for the fourth guy which needed to be set in the ground on the day.

Steve held the repeater, sundry items and spares should they be required.

The group met in Abbeyknockmoy and headed for the site. Marlow joined us and oversaw the operation on his site.

The first task was to work on the brackets to hold the pole against the wall of the hut. Gerry took charge of this with the assistance of Arek.  

The next task was to organise the staying point for the fourth guy. Joe and Andrew looked after this duty. A fair bit of digging was involved until a huge lump of rock was found. 

This rock was going nowhere so the best course of action was to drill into the rock and insert a rawl bolt. This has a couple of small clamps added and the fourth guy was affixed to this. Concrete and rocks were poured over this and then the rest of the earth covered it. A small fence was built around this area to prevent cattle damaging the guy and staying point.

The pole was raised to ascertain the length of the steel guys and also the fourth guy which would have been longer. Once this was done it was time to bolt the antennas to the pole. 

The raising of the mast was not too difficult with a little muscle and weight behind the mast

Gerry spent much of the time on the roof of the hut ensuring that the guys were secure. The tensioners did not need adjustment so there will be plenty of play to tighten them in the event of the guys stretching.

And so the last of the guys were attached and secured to the Rawl Bolt on the rock. With all in place it was time to look upward and see the results of the work done.

And then into the hut where John had been working on the installation of the Repeater and the APRS Digipeater.

A great day was enjoyed by all. The installation took four hours to complete. A great days work was done by all with special thanks to the Team - John EI1EM. Tom EI2GP, Joe EI3IX, Steve EI5DD, Andrew EI3FEB, Gerry EI8DRB, and Arek EI9GWB and not forgetting Martin List-Petersen who oversaw the operation and took the photographs shown here.

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Galway 70cm Repeater - EI7AKR

The Galway VHF Group 70 cms Repeater is now located at its permanent home on Knockroe, Abbeknockmoy, Co. Galway. This is a prime site with a superb and unimpeded view in all directions. Initial predictions using Radio-Mobile show a pretty uniform coverage of the County of Galway in almost all directions. 

As can be seen below, the coverage is impressive. This will facilitate many operators who just can not experiment with communication over distance using UHF Radio. The primary objective is to give saturation coverage of the County and, more importantly, the main routes into and out of Galway City. Regrettably, this is not possible in the direction of Clifden due to the proximity of the 12 Pins and Maamturks, however, coverage into Oughterard, and just beyond, is possible. Whilst predicted coverage is impressive, the actual mobile coverage may bring in even more surprises.

The Individual components of the Repeater are as follows

The repeater is fabricated from a modified Commercial Kyodo UHF Repeater unit running 40 Watts fed into a 4 stacked dipole array with an actual gain of 6dB. Naturally, ultra-low loss coax feeder will be used. The repeater was supplied by WESCOM and modified by Enda O'Brien EI5GMB.

To achieve the isolation between transmit and receive it is necessary to insert a bandpass/band-reject filter in line. This is one area where compromise is not an option. A set of six Sinclair cavity filters were purchased. Expensive but perfect for the job. Careful tuning using a spectrum analyser and/or a VNA was required to achieve the best possible rejection. The specification suggested that there would be 120dB of isolation between the receive and transmit frequency and we were using a 7.6MHz split.

Ideally, the cavity filter needs to be tuned into the feeder and antenna in use on-site. Although the cavity filter can be tuned into a 50 Ohm load, it will be necessary to tweak it up on site. If one changes the antenna or feeder the whole process of tuning the cavity filters has to be repeated as minor changes to the load will alter the characteristic curves. Shown below are the characteristic curves on the receiver tuned to 432.825MHz. 

We were fortunate that we were able to tune the cavity filters into the correct heliax feeder and antenna system prior to installation on the permanent site. This will reduce the amount of time spent tuning on site. It will probably be necessary to make minor adjustments before leaving the repeater once the installation has been completed.

It is now possible to run 30 watts of power without any worry about desense or drift. With the present power setting, it has been possible to get into the repeater with an S 1 signal received from it whilst it is transmitting 30 watts. This may have to be balanced on-site but at this stage, it may not be necessary. 

There is no noticeable temperature effect causing the cavity to pass or reject bands to drift. We had tried the small Procom type filters which actually heated up when our transmit signal was passed through them. This resulted in the characteristic curves to drift and resulted in desense after a couple of minutes of use. A search on the internet revealed the Sinclair cavity filters. These were by no means cheap but it is far better not to compromise the system for the sake of saving a few Euro. 

An RC-100 Repeater controller deals with the identification and timings of the repeater. The repeater is accessed using a CTCSS tone of 77 Hz as it is considered irresponsible to allow spurious triggering from a carrier operated squelch. Through this controller, the Repeater can be switched off at short notice if required to do so. 

The Antenna is the most important part of the set up.

The antenna system was obtained from Radio Structures Ltd in the UK. It was designed specifically for the task taking into account the Transmit and Receive frequencies. the Gain of the antenna is 5.5dB gain over a 1/2 wave dipole. The antenna is true Omni-directional and the characteristics are shown below. 

There is little point in producing a professional system without a professional antenna fed with low loss coax. In our case, we used Andrews heliax with negligable losses at UHF.

Status - Active

Call sign EI7AKR

Repeater Access by 77 Hz CTCSS Tone

Modulation Narrow FM (+/- 2.5 KHz)

The IRLP Node Number is 5705

The Echolink Node Number  5705

Echolink Node EI7AKR-R

Locator Reference for site IO53PK

 

Output Frequency 430.825 MHz  

Input Frequency 438.425MHz

 Frequency Shift + 7.6 MHz 

Please note Time-out 2.45minutes

Repeater Keeper - Steve Wright EI5DD

Reports to wrights1@eircom.net

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