Author: webdev

The portable-antennas.com site is a must have when you want to build a wire antenna. It takes into account all the factors that affect the lengths of the wire for many common wire antennas e.g. height of each attachment point, soil type, diameter of wire and its insulation, feed point, distance from end poles and much more. It is all in metric so no need to convert to feet and inches. Very impressive.

Types covered include normal or linked dipoles, off centre fed, end fed, vertical, delta loop, half square, Moxon and a general section.

It’s well worth a look. I’ve put a permanent link to the site in the Links page too as posts gradually disappear into the archives.

Sad news, we have been advised by Bevan’s son Wayne, that Bevan had a serious heart attack last Sunday 1/9/24. He passed a couple of days ago.

The club has lost one of its great friends. His cheery voice, his trumpet announcing his arrival for the convention will be fondly remembered as was his determination to win a foxhunt with a minimum of equipment.

Bevan’s Funeral will be held on Monday 23/9/2024. It will be available by live stream from 12:45PM.  Here is the link.

If anyone wishes to attend in person it will be held at Partridge House, 38 Partridge St, Glenelg.

President Peter

Solar panels up, Nick and Peter have been busy. Here’s the solar array up on the stand. Next comes the wiring and the installation of the solar controller.

Jack VK5EBA and Tom VK5NFT spent a busy afternoon on Sunday 19/8/24 ensuring the drainage worked well at the new site on The Bluff. Thanks fellas. Pity VK5DJ gave them the wrong key – it’s hard to get good help!

Working Bee #2  – Tuesday July 30th

Attended by :- Norbert VK5MQ, Peter VK5BE, Owen VK5HOS

Tasks completed

In conjunction with staff from CSE CrossComm, conducted further investigation into the intermittent interference that has been plaguing our 2m repeater for some time.

Assisted staff from CSE CrossComm to recover our antennas from the Hutchesson tower. Firstly, the newly acquired stacked pair of folded dipoles were recovered for relocating to Mount Graham, then the small UHF link yagi to Naracoorte was recovered, and lastly the temporary single 2m folded dipole was also recovered. All of their respective coaxial cables were also recovered.

NOTE – the linking to Naracoorte and Willalooka will be out of service until further notice.

Following the removal of the excess vegetation within the Lime FM compound at the previous working bee, Owen has sprayed the remaining areas to kill off any remaining vegetation.

Following a number of visits over several weeks the repeater team have now found a workaround that prevents the trunking radio interference from taking over the system.

Maxwell has put a huge amount of effort into the problem over this time and he now has an excellent understanding of how the Philips PRF1520 operates. It should be said that this is a very complex radio as it can be used in many ways. There are dozens of configuration jumpers and they need to be just right for our particular usage.

The main change is to use the PRF1520’s internal CTCSS hardware at 91.5Hz.

In the past when VK5RPM was transmitting and mixing with two or three other transmitters the receiver would open and we would hear the interference. This was because the 91.5 decoder was inside the controller and audio (the nasties) were fed into the audio system even though the controller was not responding to the mute.

We have now activated the CTCSS detect in the PRF15 which means that if there is no 91.5 Hz tone, not only  is the mute not activated, but the audio is also inhibited.

The repeater operation is now less susceptible to the interference. It will not show up at all if communication is coming via our links but if the incoming user’s signal on 146.3 is weak, you will hear white noise in the background or may even cause the weak signal to drop out.

This is not a cure for the interference, it just means we will not be bothered by it and we’ll have some peace!

The cause of the interference is still being investigated.

The 2M repeater has an indicator if volts are getting low. A decreasing frequency set of 3 tones on the tail indicates that voltage is low at the controller (i.e. it’s working from the battery). A quick test using the telemetry remote control indicated the volts at the controller were down to 11.9V under TX load (probably about 12.4V at the battery). Strangely the beeps  would disappear and power was apparently restored after 1.00 pm and for the rest of the day.

The SA Power Networks did not indicate an outage and yet this puzzling pattern repeated for a number of days. What’s going on?

So on Wednesday 29/5/24 an intrepid group of Maxwell VK5AC, Jack VK5EBA and John VK5DJ made the trip. On site at 2:00 pm there was no sign of the beeps re-occurring. All the meters read correctly. The battery was being charged, the repeater was using the correct amps and volts from the 230V AC power supply. The mystery deepened.

Then Jack with his extra bit of height said “What’s this?” and pointed at a timer above his head that was used to shut off 230V AC and cycle the battery between midnight and 6 am.

That was it, the power outage last Sunday lasted about 7 hours and the mechanical timer stopped ticking during that time, so when power was restored following the completion of the SAPN work the timer was about 7 hours slow and thought it should cut off power between 7 am and 1.00 pm.

If only all problems could be fixed as easily.

The Club has again enrolled in the People First Community Lottery. All the money from your purchase of tickets goes to our club. It is their way of supporting community groups. By buying the $2 tickets you’re guaranteed to help SERG and if you’re lucky wouldn’t it be nice to have one of the cars, nice TVs or solar systems?

The link to access the community lottery is:

https://mountgambier.us17.list-manage.com/track/click?u=63fe8c517be2c6db5f9585242&id=e51966f275&e=e05aeec806

The prize list is pretty good and the odds are much better than Lotto.

Here’s the prize list. Click on the image for a better quality version.