Constantiaberg maintenance 20190831

On 23/24 July the Motorola repeater was damaged in a storm. It is suspected that the repeater was damaged by static from lightning.

Roof damaged by storms

On 26 July Jan ZS1VDV and Paul ZS1V investigated and found the repeater damaged. The repeater and duplexer was removed. The antenna SWR (1:1.03) was checked.

In the following weeks a new install was planned:

  • a backup repeater serviced by Verstay (ZS1VDV, ZS1V)
  • correct length coax acquired (ZS1VDV, ZS1YT)
  • duplexer tuned (ZS1VDV, ZS1V)
  • circulator tuned (ZS1VDV)
  • power supply connector replaced (ZS1V)

The morning of 31 August started at 06:00 with the last few tests of the configuration. Backed all equipment and tools. Left for site around 07:30

Repacked all into 4×4 vehicle at ZS1DDK.

View of Hout bay

On site around 10:00

Duplexer and circulator

Installed duplexer (Decibel Products 6 can). It was tuned to -2.04 dB insertion loss on RX, -2.5 dB insertion loss on TX, and -115 dB isolation between RX and TX). Next was the installation of the rack mount power supply (13.82 V) and Vertex VXR 9000 (sensitivity set to 0.25 uV) repeater.

Power Supply and Repeater

SWR was rechecked between repeater and circulator, circulator and duplexer as well as after duplexer, all was found to be perfect flat (1:1.05). The power output after the duplexer is 14W.

Folded Dipole just above first landing

A few test contacts was made to confirm all working.

Packed all equipment and boxes and returned home at around 11:30

A quick lunch sponsored by ZS1DDK was enjoyed at Peddlers on the Bend.

Hanskop maintenance 20190707

Problem: About 2 months after the big rebuild in September 2018, the UHF repeater was starting to drop out after a few seconds of transmission.

This lead to a long fault finding process with help from the high site managers’ personnel to save on trips to site, on a very bad road.

After 4 months of problem finding, it was concluded that was not the repeater and not the antenna, but most probably the duplexer.

The WCRWG do not have a spare 1.6MHz split UHF duplexer. One was constructed out of spare notch cans. This happened over a process of 2 months, to make up a custom duplexer coax harness and trying to get the pass-through SWR as low as possible. With everything ready, it took some planning to get the vehicle, weather and correct people aligned to go do the swop out repair on site.

It started at around 06:30 today. Packed the repeater, swop-out duplexer and all required tools. Next was the pickup of keys.

Vehicle packed and ready, All in good spirit after the coffee ZS1V provided

The team (Sybrand ZS1SJ, Paul ZS1V and Jan ZS1VDV) got together at around 08:00 to repack all equipment into the 4×4 to go up.

Hanskop in the clouds

Around 08:15 the trip up started. Sybrand got a few chances to use the 4×4 capabilities of his vehicle.

On site the repeater was reinstalled. Next the debugging of the high SWR around the duplexer was completed. SWR straight on antenna 1.2. SWR through duplexer to antenna 1.8. SWR through duplexer to dummyload 1.0. It was concluded that the current duplexer on site was also not the problem. With a bit of head scratching a short patch lead was added to the antenna feedline. That took the SWR through the duplexer down from 1.8 to 1.3.

The last part was to correct the power sensing of the controller. Suddenly the UHF repeater started to restart on transmission. With some debugging it was found that the 10 A PSU used on the UHF repeater was suspect. This PSU was removed and the UHF repeater moved over to the main 30 A. The total current draw is just below 20A on full transmit. The calibration of the power sensing was updated and the voice responses also updated.

DTMF:

  • 8323 – Controller Voltage (This is the main power supply when on mains, and battery when on backup power)
  • 8324 – Main PSU voltage
  • 8325 – Battery voltage
Team photo in the clouds with tower in the back

Everything was packed up and returned home. Home around 13:00 and unpacked by 13:30.

Jonaskop maintenance 2019-06-29

On 26 June it was reported that the repeater is not functioning and constant keying.

From the detailed fault report it was concluded that a power supply is the most likely problem. However with power problems, there could also have been big equipment failure.

Paul ZS1V and Peter ZS1PDE assisted with the ordering and pickup of a replacement PSU for the site.

Jan ZS1VDV packed for all scenarios on Friday evening. This included making controller link cables for the spare repeater.

All equipment ready and packed

Saturday started very early with Sybrand ZS1SJ meeting up with Paul to collect keys and replacement PSU in Somerset West.

Sybrand next was picked up Jan ZS1VDV and loading all equipment in Stellenbosch at around 07:20.

Sybrand driving 330km for the day

A route via Worcester to Jonaskop the best option, as the Franschhoek pass was closed and the round via Grabouw to Villiersdorp was reported on Thursday to have loads of sand after the winter storms,

Arrived on site, it was very clear that this was going to be a very cold and windy visit. Around -2.5 C and very strong gusts of wind.

Sybrand hiding from wind

As soon as the repeater hut was opened, it was found that the repeater was on backup power (measured to be 12.8V). This was very strange as the repeater never went to backup power during the week. Next the PSU and 220V was tested all over the site, and found the no 220V was available. With out more information, it was decided to swop the PSU.

Isolator after lighting strike

On the way down, Eskom was found working on the line. At this stage it was clear why the repeater was on backup power. In the process of driving up, Eskom switched of the 11 KV line to work on it. The 11KV line was hit by lightning and an isolator needed to be replaced. With the one line on the delta 11 KV line down, the transformer would have converted to 220V star 3 phase, but the 220V would not have been stable. After about 1.5 hours the repair was concluded. They had to use a gas flame to shrink the heat shrink on the lug.

Eskom replacing isolator

Returned to site, checked that all power was up and running. It was found the that controller configuration was corrupted and needed to be updated. The main and battery sense DTMF codes was also swopped as listed on the TODO list for the site.

Jan using repeater hut door to hide from wind to configure controller

The link radio the Hanskop audio levels could not be realigned as it was just to cold and wind to strong.

The tower guy lines was giving a quick inspection and found that they will need service on next visit.

Unpacked in Stellenbosch around 14:00.

Sybrand last stop at home around 14:30 for a total round trip of 330km.

Sutherland Repeater maintenance 2019-06-11

Transmitter:

Output power:                  21.6W
Frequency error:              -315Hz
Deviation:                          1.49kHz

Receiver:

Sensitivity:                          0.683uV for 12.2dB SINAD (NOT CCITT weighted)
                                             @1.5 kHz deviation AT 1kHz
Squelch                              Could not be measured. Comms test set only goes down to 0.350uV

TX Filter unit:

RF power before filter:   42.63dBm (18.3W)
Return loss:                       3.4dB  !!!!!!(VSWR 1:5.23)
RF Power after filter:      34.3dBm (2.7W)
Antenna Return loss:      15.7dB (VSWR 1:1.39)

After tuning the filter unit, I got the following results:

RF power before filter:   42.85dBm (20.1W)
Return loss:                       23.2dB (VSWR 1:15)
RF Power after filter:      40.34dBm (10.3W)
Antenna Return loss:      15.7dB (VSWR 1:1.39)

RX Filter unit:

Measured loss at intended frequency:     20.6dB
Isolation at plus 600kHz                               Around 50dB

After tuning the filter unit, I got the following results:

Measured loss at intended frequency:     2.4dB
Isolation at plus 600kHz                               Around 50dB

Repeater without filters at high input RF level; 20uV 88.5Hz CTCSS @400Hz and 1.5kHz deviation @1kHz tone

Repeater without filters at low RF level; 0.683uV 88.5Hz CTCSS @400Hz and 1.5kHz deviation @1kHz tone

RF power going into the filters. Note poor return loss.

After tuning the filter. Note marker on 145.000MHz. Reference at the -10dB mark.

Results after tuning the TX filters.

Receiver filters before tuning: Reference is at the -10dB mark (-22.6dBm) indicating filter loss at 20dB.and off frequency.

Receiver filter after tuning. 2.4dB loss and on frequency. +600kHz isolation of around 51dBm

Repeater performance through both TX and RX filters after tuning filters.

The Site: Gentle reminder not to tamper……..

Conclusion:
I could probably get better results tuning the filters if I had the directional coupler with me. Maybe next time. I would have also preferred to have the manufacturers specifications to test against but did not have at the time. In my experience the repeater performs well according to what I measured. I tested the repeater from the town using a 5W hand held radio and got full quieting from the repeater with good quality audio. I there is someone who can test from the N1, some feedback would be great.

Report compiled by Neville Gleeson (ZS1NEV)

Site tested by: Neville Gleeson (ZS1NEV) and Deon Lamprecht (ZS1AFU)

Hawequa maintenance 2019-06-09

On Sunday a team of four consisting of David ZS1DDK, Mike ZS1TAF, Markus ZS1MTB and Rassie ZS1YT left home at 7h00 to meet at the site gate at 8h00. The purpose of the visit was to replace the 3 cable stays on the tower with new Stainless Steel cables, clamps and turn buckles.

Stay replacement

A 6m dipole was also fitted to the tower for future linking of a 6m simplex radio onto the repeater system.

Although quite a strong wind was experienced, the temperature on top of the mountain was a very cool 18o C.  Work started immediately with Mike and Markus climbing the tower and David and Rassie fixing the cable stays on the bottom anchor points. The team returned home by about 12h30.

6m antenna

The 6m Webb-antenna and Stainless Steel cable was donated by Rassie ZS1YT

The antenna clamps, cable ties and other hardware was donated by Mike ZS1TAF

Travelling to the site by ZS1TAF, ZS1MTB and ZS1YT was also donated.

Onrusberg visit

On Sunday 4 November, a team consisting of David ZS1DDK, Jan ZS1VDV and Paul ZS1V visitted the 145.725 repeater site at Onrusberg with the intention of returning the repaired Tait repeater and retrieving the Kenwood TKR-750 which had been put there as a temporary measure.

David collected Jan at 06:45 and Paul at 07:15.  The team reached the site at around 09:30.  The Tait was re-installed and the Kenwood removed, but despite introducing a bandpass filter to the receive path, the Tait’s front-end was not suited to the high noise on the site.

Consequently, the Kenwood was returned to service.  The bandpass filter was left in place.

Photo: ZS1DDK

Piketberg Visit

On Saturday 3 November, Jan ZS1VDV and Paul ZS1V left Stellenbosch at 06:00 to visit the 145.625MHz repeater site at Voorstevlei near Piketberg.

Towards the end of October the UHF radio for the link from Piketberg to Hawequas locked into transmit.  The link repeater at Hawequas had to be temporarily disabled to prevent the rest of the link network also locking in transmit.

The team arrived at the Piketberg site at around 8am.  The problem was narrowed to a faulty buffer chip in the link controller.  The chip was replaced with a spare and the fault cleared.  The link controller was also updated to the latest firmware.  A bandpass filter was also added to the receive path.  That eliminated interference from a nearby DMR repeater.

At 09:45 the team packed up and departed Piketberg for Hawequas.  There, the link controller settings were adjusted and a damaged connector seal on one of the antennas was repaired.

The exterior temperature sensors at both Piketberg and Hawequa have not stood up to the elements and are faulty.

The team arrived home just after noon.

Constantiaberg maintenance

On Thursday 11 October, Mike ZS1TAF and Paul ZS1V took a day off work to take advantage of an opportunity to access the Constantiaberg Sentech site, home of the 145.700MHz repeater.

The site was last visited by Sean ZS1BSD and Paul ZS1V during mid-2017.  At the time, they diagnosed a problem with the antenna/feedline, but there were no Sentech personnel on site and so, despite being certified to climb, Paul could not attend to the antenna problem.  Since then, there have been numerous changes to the management at Sentech and communication has been difficult.  Gustav ZS1NZ, who works for Sentech, alerted the WCRWG to an upcoming Sentech maintenance run earlier in the week and so plans were hastily put in place for Mike and Paul to take leave and visit the site.

The team met the Sentech technician at the security checkpoint at 9.30am and proceeded up to the site.  Despite the warm weather at the bottom, a cloud on the mountain ensured cold and wet conditions at the mast.  The SWR at the bottom of the antenna feedline was measured at 2.5:1.  The high SWR presumably caused damage to the repeater which was transmitting well below 1W.

Despite the unpleasant climbing conditions, Mike headed up the tower to open and inspect the connection point between the feedline and the antenna, but this was found to be well sealed and dry inside.  He swapped out the antenna for another and the SWR was measured at the bottom at 1.3:1.  Paul swapped out the repeater and removed the bandpass filter for re-tuning.

The team left the site just after noon, to enjoy a cold one in a warm and sunny Tokai.

 

Hanskop rebuild 2018-09-09

On the morning of Sunday 9 September, a team consisting of Jan ZS1VDV, Mike ZS1TAF, Rassie ZS1YT, Paul ZS1V, Ohan ZS1SCI and JP ZS1JPM headed to Hanskop to perform a major site re-installation.

Approximately two years ago, the tower at Hanskop blew over in a storm and all the antennas of the tennants on the site have been temporarily mounted on the building ever since.  The new tower and cable trays have been recently installed and once the owner of the site had moved his own equipment on to the new tower, we were invited to install next.

The journey to Hanskop has become quite challenging.  The usual access route has been all but washed away, necessitating navigation along some even more minor tracks.  Even those are flood damaged and deeply rutted, some with pools of water 30 to 40cm deep and 50 or 60m long.   The weather on the morning was cold – around 4C – but Hanskop was uncharacteristically wind still and so all team members jumped into action after arrival on site at around 9am.

While one group removed the temporary antenna pole from the side of the building and removed the antennas from it, another re-organised all the equipment in the rack, moving the equipment up to make space for the new battery backup system at the bottom of the rack.

New backup batteries

Rassie ZS1YT constructed a shelf to go over the batteries, allowing the duplexer and bandpass filter for the 2m repeater to stand above them.

Duplexer and battery charger on shelf

Equipment reinstalled

New cable gland plates have been installed in the building. New RG214 patch leads for inside the building were made up and attached to lightning protection devices.

Feedline connection points for the 70cm repeater, 2m repeater and 70cm link to Jonaskop

Outside Mike ZS1TAF was left to solo all the tower work after Paul ZS1V was unable to climb due to illness.

Mike attaching the feedline to the link antenna

Mike attaching the UHF repeater feedline to the antenna

Mike installed the three antennas, attached their feedlines and secured all the cables to the mast.  On the ground, Jan ZS1VDV and the rest of the team prepared the feedlines, installing the connectors and routing them in the cable trays to the exterior of the gland plate.

Feedlines being secured

Feedline wrangling

Final measurements showed the antennas reacting well.

Antennas installed

The team packed up and left site just after 3pm.

Maintenance Hanskop 20180707

Jan (ZS1VDV) and Rassie (ZS1YT) went to Hanskop reconfigured the repeater controller and did all measurements for the big site power upgrade and antenna migration.

Most site visits starts the evening before the time with a 1 hour planning and packing session.

Tools and Spares for trip

Wake up 06:30, pack vehicle.

Leave for Strand 07:30 from Stellenbosch.

Pickup key 07:45.

Drive to site, which was very long and challenging drive. Had to “find” a way to the top.

“Finding” the road

MMMM, where to now?

Some holes with bakkie for size reference

08:45 arrive on site.

With all the power interruptions and no backup power, the site controller’s EPROM got corrupted. Reprogrammed the controller. Changed default for links to VHF and East. (please see updates DTMF updates on Hanskop)

Did some detail measurement for coax and battery placements.

10:00 left site.

11:45 Home in Stellenbosch

12:00 Finished unpacking.