Published: 23/12/2023

Hi All, Happy Festive greetings to you all. Just a quick note to inform members of the repeater group that the 2023 newsletter has now been published. If you have not received your copy via email then please get in touch with us and let us know.

The weekend before we were due to have our antenna replaced (See below), Mark and I took the new replacement antenna, and some coffee making supplies to site ready for the antenna riggers.

HOWEVER on arrival we were met with a strong smell of hydrochloric acid.  Initial thoughts were one of the generator starter batteries had been boiling. Neither of us was prepared for what we found.

One of the two 12V batteries (connected in series to produce 24V) had not only been boiling, but had been producing hydrogen gas, which looked to have ignited causing a hydrogen explosion blasting, yes, blasting the side out and top off the battery. All cell filler/pressure release valves had also blown, and caps were found all over the generator room.
Forward of the “Blast Area” the contents of the battery had been liberally sprayed coating the under side of the generator, and the wall to the left of the battery to a height of around 1.8m. After a loud use of an old English phrase, followed by a Norwegian and French phrases, we noticed that the other battery was also bulging.  The power to the charger was turned off and a closer look at the batteries took place.

After disconnection from the generator they were moved, double rubble sack’ed (I knew the sacks that I took to site several years ago would be handy one day) and placed into a couple of thick wall boxes that were due to be crushed and taken home, again that was lucky.  We contacted control and warned them of the events more out of respect as they, after all are our landlords and do occasionally enter the generator room to carry out electrical inspections.

The following day we returned to sight armed with a couple of dubs of bicarbonate of soda, a spray bottle and water. Mixing this all up and spraying the “Blast Zone” watching it fizz. This was repeated until the fizzing stopped, meaning the acid had been neutralised.

We then inspected the charger to see if it was over volting, but found it was dead. Volts in but nothing on the output. The Charger is a low current device, designed to simply float charge the batteries. So it was unlikely to been the cause.

A call to BBL in Bristol, along with a couple of photo’s emailed to them lead us to a bit of a stark discovery. They (BBL) were able to look up our purchase history and found the batteries were over 8 years old. Batteries this old apparently suffer from internal warped plates and a Generator Start could have caused stress to the battery and warped the plates enough to cause a low resistance. The trickle charger would have had enough current capability to cause heat build up, leading on to hydrogen build up, and finally the heat from the plate plus the pressure ignited the gas. BBL said it was a good job we were not present as we could have been sprayed with a fine mist of hot hydrochloric acid, or burnt if they had been an explosive flash.

While on the phone we looked at ordering replacements. Taking guidance from BBL we purchased a pair of No Maintenance batteries that use cylindrical plates, and produce a better cold crank current that our traditional wet cell batteries. Of course we had to replace the now dead 30 year old charger with a modern unit.  We simply loaded to old batteries into the car and went down to collect the new parts. BBL dispose of the old batteries in an environmental manor, which means they old batteries get recycled and do not end up in land fill.

We returned to site and fitted the new batteries and charger. The batteries are half the size of the wet cell batteries, and as Marks Testacies can confirm, about a quarter of the weight of them.

The charger itself, one the old one was removed off the wall occupies not even quarter of the old chargers footprint (Nicely outlined by the marks left behind after being sprayed with battery acid.

All in all June/July has been a very heavy on the repeater groups’ funds. What with, The failed antenna, having to engage a rigging company to carry out the tower work and now the battery and charger has left a big dent.

IF anyone wants to make a large donation to the repeater group it certainly would be welcome. One can dream.

On a normal site maintenance visit in June 23 we discovered that the return loss of our primary antenna had crept up from -23dB to around -10dB. This meant only one thing, the antenna had all the signs it was starting to fail.

The Group were forced to purchase a new commercial grade antenna (a UHF 4 Stack from Radio Structures).  We were also required by our landlords to use a certificated rigging company.

On the 20^th July after a month of paperwork and phone calls the antenna was replaced.

The return loss on the new antenna is now back to the -23/24dB level.

A full report will be in our 2023 Newsletter published later this year.

The above picture shows one of the 4 elements of the 4 stack antenna with a noticeable crack in the moulding.  All but one element had cracks allowing water to penetrate into the coax phasing harness. 

The riggers came equipped with drone surveying equipment that they used to look at the antenna before they sent men up the tower.  Celtech were kind enough to allow us to use some of their drone footage to produce a short video which was uploaded to the Repeater Group’s YouTube Channel.

This can be found HERE

Something Wonderful

The title of this news item may confuse some; much as it has our recent Facebook postings and YouTube viewers.

It was aimed to get peoples attention and raise interest, which may of lead to questions being asked.

Since its concept in 2014, the SouthWest Cluster (SWC) has existed to provide a reliable, simple to use, DMR Network across partner repeaters in the area. Over this time period a few early adopters into the cluster have moved on to other Networks. (This is one of the mantras of the SWC. Groups are encouraged to manage their own repeaters and their own destiny’s). But generally, member repeater numbers have increased.

This has caused us a little, not so well known predicament!

Motorola by design only supports up to 15 devices. One of those is known as the “Master Repeater”. This repeater holds a database of all the SWC Repeater members connected to it, and distributes data to the other repeaters so they learn about each other.

We have grown to 10 repeaters at time of writing this, along with a couple of monitoring units we use to help maintain the cluster, this brings us to 12 units. And we have another two repeaters interested in connecting into the SWC. So we are quickly reaching the magic number of 15.

Mark – G4SDR and I have been working on this ’15 is the max number’ problem for over 2 years; one solution would have cost lots of money. But late last year we became aware of FreeDMR. Since then we have been working with Simon and Jon from FreeDMR here in the UK who have kindly customised their software solution to meet our requirements for the SWC.

Compare the old network layout to the new network layout. Keen eyed among you will spot two things. The first thing: GB7BS has been demoted from being the ‘Master’ repeater (That role has been taken over by the server) to being a Peer, just like all other SWC repeaters. 

The second thing: “Dial on demand Talkgroups” on Slot 1 Talkgroup 9 (next to the red line going to the internet). No, this is not a printing mistake; Talkgroup 9 will continue to be your local repeater only Timeslot/Talkgroup, as it does now.

However, one of the “Wonderful Things” that FreeDMR brings to the SWC is a function called “Dial on Demand” Talkgroups.

Anyone tuning to your local repeater while you’re using a dial on demand Talkgroup will hear that Talkgroup, and can join in without having to change any settings on their radio or hunt for the Talkgroup in use.

All we do ask is, once you finish a DoD QSO, Manual dial Talkgroup 4000 and press PTT for a second to Disconnect you. You will hear the message  “Not Linked”

Dialling TG 5000 (PTT) will cause the server to report either the currently dialled and connected Talkgroup number, or simply report  “Not Linked” if no one is using a DoD.

Just a few last things about the new Timeslot 1 Talkgroup 9.

• While using DoD you’re only tying up your local repeater not the whole SWC.
• There is no DoD timeout unlike some networks. You want a 50 min QSO you have it.
• If someone leaves a DoD Talkgroup active (Shame on them) the system will automatically disconnect it after 10 minutes of inactivity.
• Every 15 minutes you will hear your local repeaters Callsign beacon. This is only on Slot 1 TG9 and in speech.