Phase III - Abbeyknockmoy DMR On Air

On Saturday the 16th of October EI7AKR, the Abbeyknockmoy DMR Repeater was installed on site at Knockroe, Abbeyknockmoy, Co Galway and appeared on air at 16:30.

Sadly, our previous attempt to put the Repeater on air saw a total disintegration of the 4-Stack array and therefore we were unable to switch the equipment on. Radio Structures LTD supplied us with a new antenna, under a 3-year warranty agreement, so our trip on the 26th of October was to install the replacement antenna. 

On this occasion, our team consisted of Aengus, EI4ABB, who was responsible for tuning the cavities into the antenna system, Steve, EI5DD, who programmed the Repeater along with Tom, EI3ER, Joe EI3IX, and Enda EI3IS who installed the new antenna system.

This site provides the primary coverage of Co. Galway as it is located almost in the middle of the County a superb height and an excellent Radio Horizon in all directions. This will facilitate communications on all roads into and out of Galway.

The antenna system is the same as used for the previous Analog Repeater located at this site. The antenna is an RF Structures Ltd. 4-Stack Omni-directional antenna offering 6.5dBD of gain. The antennas are built to withstand the worst of weather conditions and therefore ideal for the purpose.
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Some Excellent views towards the horizon

The new 4 Stack Omni-directional antenna is pictures above as of 26th October 2019

Aengus, EI4ABB, assisted with the installation and made sure that the Sinclair Cavity Filters matched the Antenna system. Despite perfect tuning at ground level, the impedance of the antenna is seldom exactly that of the dummy reference antenna leading to losses. Often only minor tuning was required to obtain perfection on-site into the 4-Stack array.

Whilst the Cavity Filters were checked, Steve, EI5DD, locked the Network settings into the DMR Repeater and ensured that the connection into the Brandmeister network had established. A quick check followed to ensure that all other settings and levels were correct.

On power up the Repeater appeared on the Brandmeister Dashboard - a great sign that all is well. The power levels were then increased to 40 watts. On Re-boot, there was no indication of desense detected on the receive side. A quick tidy up of cables was performed and finally, the remote switching equipment was installed.

A scout around the shack was in order before leaving the site and to make sure that we left nothing behind as we would not be going back to that location for at least another year. 

A check on the Brandmeister Dashboard revealed that all was well so we now have three out of four DMR Repeaters  and one multimode Gateway on site and operational within one year.

 
The Coverage of the Abbeyknockmoy Repeater is as shown below

Combining the Abbeyknockmoy coverage with the Inishbofin Repeater EJ7IBD, and the Galway Repeater EI7RHD it can be seen that the Network is slowly coming together.

The addition of the Loughrea Repeater EI7LRD will complete the Network. Uniform coverage with saturation of the majority of the County will be possible. This will facilitate Roaming where the user radio can switch between repeaters according to received signal strength. Should one of the Repeaters shut down, for any reason, ample but reduced coverage will still be possible.

We look forward to installing the Loughrea repeater on-site in the near future.

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Catastrophe - The Best-Laid Plans of Mice and Men

With all items packed and ready to go on site to install the Repeater, it was a perfect sunny day with an excellent panoramic view in all directions from the hilltop. The gear was unloaded and installed into the hut in the site at Abbeyknockmoy. The Cavity Filters for the Repeater were given their final tune up and the Repeater was installed and connected to the network without a problem. Almost straight away the signals came through via the network. A pleasing conclusion will be found at the end of this write up.

Great we thought. Job Well Done! We placed the APRS system on air and it came to life as soon as we connected it. Better again.

And then we peered up at the antenna system. Well there were not enough swear words in the dictionary to describe the situation and none of them were repeated twice. The Repeater antenna was totally destroyed and all its components were draping down from the pole.

What was originally this:

was now this - all of the dipoles had sheared off the pole where the clamps holding them to the pole had disintegrated.

Naturally the Repeater is currently disconnected until further notice until we can replace the antenna. Hopefully Radio Structures Ltd will replace the antenna which has only been on site for 1 1/2 years.

The pole had suffered a little with the high winds and seemed to be a little bent on the bottom end where it was clamped to the pole

This was part of the clamp that held the dipole element to the pole. The others had completely disintegrated and disappeared,

This is the other part of the clamp which had litereally shattered like china.

A sad end to what could have been a really great day.

Epilogue

The Good news, however, is that a very quick respose was received from Radio Structures LTD who have offered to replace the antenna under a three year No Quibble Warranty which were were unaware of at the time. The replacement antenna was dispatched on Monday the 14th of October, just 3 days after sending an Email on Saturday.The antenna arrived in Galway on Friday the 18th of October.

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New Life For The Galway Analog 70cm Repeater

Our 70cm Repeater was recently removed from its high site in Abbeyknockmoy prior to the installation of a Hytera DMR Repeater. It had been on site for some time and, whilst it proved itself to be an exceptional Repeater, very few made any effort to use it. Coverage was over a colossal distance considering that this was a UHF Repeater. One journey, from just outside of Limerick,  to Claremorris in Co. Mayo yielded a Strength 9 signal for the majority of the journey. Why nobody took an interest in this Repeater is difficult to comprehend, as it had a coverage far superior to many 2 metre repeaters around Ireland.

On Examination, Aengus, EI4ABB, noted that there was an accessory plug on the back of the repeater that would make it possible to extract raw unprocessed audio from the receive side and allow encoded audio to be transmitted. This would be perfect for a mode such as D-Star. Just by chance, Aengus had the appropriate circuitry from a project that never saw completion. The perfect opportunity to try to see if it would be compatible. 

Amazingly, Aengus did not have this Repeater on his bench for more than a couple of days before the project took shape and was ready for testing. The cavity filters had recently been tuned up in preparation for use with the DMR repeater when it was to be placed on its site in Abbeyknockmoy. these worked well into his own antenna so it was possible to try out the D-Star build.

Steve, EI5DD, was working in his shack on DMR repeaters scheduled for re-location sometime in the future. A call was received from Aengus on TG 2722, for assistance with the initial tests. After disconnecting the DMR repeaters, the D-Star Radio was hooked into an antenna and the initial call was made. 

Apart from a bit of feedback from equipment in Aengus's shack, the audio was very good. Obviously, this wasn't the completed project, but very promising results were achieved. The Audio was crisp, clear and stable - the system was working. Great potential for this project.

Whilst D-Star is probably the least used digital mode in the Galway area, the opportunity to experiment is available as well as for the other Digital Modes. We have multi-mode systems that also encompass D-Star operation which will cater for may forms of experimentation. 

This equipment will run initially as a repeater until we register it on the D-Star network and then its full potential can be realised through the D-Star system. This is really quite remarkable progress as D-Star had only been tested in July through the multi-mode Gateway before we followed up with the acquisition of a multi-mode Repeater for Galway City in September.

The pictures below show the Kyodo 70cms Repeater gradually nearing completion with its new components for D-Star.  

Finally, everything  installed and covers back on the units ready for further tests. Delighted that the Kyodo Repeater still has a function, and place in the Galway area, as it had a very sensitive receiver and the transmit otput power was more than adequate on UHF operation. As if by magic, a new Repeater was born

Subsequently, the repeater has been fitted with a set of cavity filters and is operating on RB14.

RB14 - Input: 434.950, Output: 433.350. Analog CTCSS 77hz

Special thanks to Aengus for his time and effort and we look forward to this going on a high location.

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