SERG was well represented today (Saturday 10/4/21) by Peter VK5BE, Col VK5HCF, Andrew VK5VKC, Tom VK5EE and Andrew VK5MAS at the Reidy Park Centre working bee to extensively trim back the much over-grown hedge at the rear of our Clubrooms. Also thanks to the 2 Andrews for towing 2 of the 4 fully loaded trailers away.
Members from all groups contributed to the exercise making quick work of a mammoth task. This has resulted in the Reidy Park Centre saving hundreds of dollars in maintenance costs, which has now been passed on to all the Groups in the form of a rent reduction.
Last month I reported that negotiations to secure a site sharing agreement with the new land-owners of Mount Eckersley had broken down and that we had begun negotiations with the land-owners of the neighbouring property to secure a site sharing agreement.
Unfortunately, these recent talks have also failed to secure the rights to install the proposed Heywood repeater on Mount Eckersley.
Not to be deterred, a search for an alternate site has begun, with a number options being identified and considered.
Hopefully we can secure a formal site agreement in the near future to locate the Portland repeater.
In the mean time, the VK3RSW repeater remains on test on-air from the SERG clubrooms, and is linked into the existing South-East network and you are all encouraged to try it out.
Ross VK3KBO has put up a temporary link antenna at Naracoorte and the link has been turned on. Things need to be working well again. Well done Ross – a high gain home brew 10 element beam is doing the job very nicely. Great to have the whole network back on again
Peter VK5BE has been busy too. He grabbed one of our spare cavities from the clubrooms and tuned it up as a band pass filter using his tracking generator/spectrum analyser. The idea being to cut out harmonics from the 146.9MHz transmitter on the basis that maybe the mixing products we have been experiencing are related to a harmonic mix. The first harmonic at 293.8MHz is now filtered out by at least 40db and higher harmonics even further down. Peter installed it at The Bluff today (8/4/21) and so far so good, no noise. Have we spoken too soon! Thank you Robin for being the testing station from the Mt Gambier end. We’ve lost a little output power but if that means no noise I think we can tolerate that.
Update: Spoke too soon. Still having noise problems, maybe, just maybe, not as bad. Seems OK on weekends but weekdays are a different matter.
Today, March 29th, Peter VK5BE and Colin VK5DK completed the recommissioning of the VK5ROH 70cm repeater at The Bluff, together with the Echo-Link gateway from the Clubrooms. All appears to be working as it should. Attached pics are of the Echolink antenna and measurements at the Clubrooms. Cheers, Peter PS : I haven’t tested the IRLP facility (Editor: it’s not currently working), so I’m not sure if its working, but Echolink works fine.
Today, Colin VK5DK and I had a very successful activity at The Bluff to restore our 70cm repeater, VK5ROH, following the mounting of the dipole array last week-end on the Hutchesson tower.
Correct galvanised bolts fitted to the array mounting brackets. Dipole array realigned to face north. Coaxial cables neatly routed down the tower to our hut. Custom cut extension cables using RG-213 installed to the rack equipment.
Tx SWR = 1.13 to 1 Rx SWR = 1.08 to 1
Initial signal reports suggest the coverage is as expected.
Note from VK5DJ At the top of the photo, just to the right of the tip of the Mt Benson yagi you can see a 2M vertical dipole. This was installed by Gambier Electronics for us some months back and had some performance issues when used as a duplexed antenna. Sometime in the next week I plan to drive to The Bluff and put that currently unused antenna on the receiver but leave the transmitter on the top phased dipoles. It’s worth the try to overcome the poor receiver performance. I may be able to remove a received cavity also.
On Sunday 21-3-21 we had a get-together at the Bluff. Tim VK5AV and Norbert VK5MQ set up HF portable operation for the John Moyle field Day. They had some success, Tim using a horizontal wire and Norbert tested his vertical. Forty metres was the best band.
Col VK5DK and Gary VK5JR setup 1296MHz equipment but failures prevented successful operation. An attempt by Gary and Norbert to get a 1296MHz contact over 200m was unsuccessful as the contest time ran out.
It was all great fun, we had a good turn up of members considering the short notice. President Peter also relocated the UHF repeater antennas on the tower although the coaxes will wait another few days.
More work over the weekend. Saturday attendees at the Bluff were Peter VK5BE, Col VK5DK and John VK5DJ.
Three main tasks: 1) Remove the UHF antennas from the fence ready for the site inspection this week. 2) Install the Mt Eckersley/Mt Gambier Clubrooms linking yagi on the Gambier electronics tower. 3) Install an additional filter in the main receiver cavity line.
So what happened? 1) UHF repeater was turned off and the antenna laid on the ground neatly against the fence, Peter guiding the pole and Col and John bravely holding the end of a rope doing the lowering.
2) Peter brought along a long ladder and has installed the yagi pointing at Mt Eckersley about 7 metres above ground level. He and Col arranged the coax in a neat but temporary fashion. Rather than cut the long length of heliax, a temporary coax line was built out of three shorter pieces with two joiners. A compromise until we know if the yagi is high enough to get through to Mt Eckersley. Once this is confirmed we’ll make the coax one length. Tests show that the link is very strong into Mt Gambier and can be heard off the back of the beam in Millicent.
3) It was suspected that there were strong signals (or noise) overloading the 2M receiver. The cavity shown to people last Friday was retuned at Millicent to 146.3MHz and installed on site. Using a return loss device it was possible to show there was an additional 10dB of sensitivity gained by inserting the additional cavity. As an aside some of the noise from nearby transmitters can still be heard on signals into The Bluff receiver but this can’t be filtered out for obvious reasons. The overload problem is fixed. Noise is just a feature of the site – there is so much RF on the hill.
Some measurements of the cavity performance at spot frequencies: Commercial TX on site 70MHz -45dB Commercial FM radio on site 96.1MHz -41dB Repeater input 146.3MHz -0.39dB Pagers 148MHz -18dB Commercial services 160MHz -41dB
What does 45dB down look like? It might be easier to picture that as the power is down by 31,600 times. That is a great filter! Even 18dB down is a reduction in power of 63 times.
On Sunday Peter and Col returned to the site as the link output had suddenly dropped off and signals became noisy into the link input of the Mount Repeater. Examination showed that the relay had failed in the link. These relays are 40 years old being ex-FM828. Fortunately there was an unused relay system in the link frame so Peter with judicious use of a soldering iron, various tools and great patience, was able to do a successful swap. Well done Peter. The link is now outputting 8W and all is good back to the Mount.
We hope to have the UHF antenna back up later in the week after the site inspection although a more permanent installation onto the tower is planned.
VK3RSW on test – now linked into the SE 2m network
Today, Saturday February 27th, the Heywood repeater that was put on test recently at our Clubrooms, has now been linked into the South East 2m repeater network.
This repeater will allow members to access the SE network from the city of Mount Gambier, and its immediate surrounds.
This will be of a benefit to those Mount Gambier members who are currently experiencing difficulties in accessing The Bluff repeater due to an ongoing issue with its coverage.
The SERG repeater team have been working tirelessly to provide the best coverage possible during these uncertain times.
The repeater at the Clubrooms transmits on 146.875 MHz, and receives on 146.275 MHz. (No CTCSS tone is required)
It will be available for all Sunday broadcasts, and Friday night meetings and skeds whilst on test.
In order for this linking to occur, the IRLP/Echolink facility on our 70cm repeater will be unavailable until further notice. The 70cm repeater remains available, it’s just that we’ve temporarily made use of the UHF antenna at the clubrooms preventing this end of the link for IRLP/Echolink. Another antenna is being explored.
Just a brief update following activities at The Bluff today. Colin VK5DK, Owen VK5HOS and myself (VK5BE) attended. Owen VK5HOS has a brilliant plan on how to repair the big hole in the floor of the hut. He will manage this issue through to its completion, hopefully by the end of next week. The pole mounted temporary VHF array has been removed from the site and returned to my QTH until required for the Heywood project. In its place, a RFI YB9 yagi (450-470MHz) has been installed on the vacated pole, horizontally polarised, and facing the Clubrooms in preparation for linking the Heywood repeater to The Bluff. The yagi SWR was measured at 1.13 to 1 at 449.875MHz. We figured this was acceptable. Initial tests show excellent solid signals are being received in Mount Gambier. Tomorrow we plan plan to erect another yagi at the Clubrooms to link the 2 sites.