On Saturday 25 April, ZS1VDV, ZS1V and ZS1RK visited the Hawequa site, home of the 145.650 repeater and 438.800 link repeater between Piketberg and CPUT. The 4 x 200AH backup batteries donated for the purpose were installed with their fusebox and charger.
In addition the Vertex/Motorola repeater system swapped out for a pair of Kenwoods, a TKR750 VHF and a TKR850 UHF.
The waterproofing of the antenna connectors was also inspected and found to be in good order for the coming winter.
Meetup at gate (at tar road) +_ 09:00.
Drove up.
VHF Repeater
Connected a test repeater direct to duplexer (By passed all filters and pre amp except duplexer). Repeater was set at 0.22uV to open.
Received ZS1GVW with lots of rain on signal (ZS1GVW running 20w)
Received ZS1GVW clear (ZS1GVW running 60w)
Did receive some interference on RX.
Tested if CTCSS was a good enough filter (Confirmed).
Local RF noise suspected to be around 0.3uV
Removed 1 can from Celwave cavity set and retuned for 145.750 (-0.58dB insertion loss)
Replaced VHF Engineering Bandpass filter with Celwave cavity (Insertion loss moved from -2.7dB to -.58 dB)
Bypassed one of the two cavity bandpass filters in RX side (left -0.97dB)
Reconnected the installed PYE repeater.
Power after duplexer up by 60% +_ 15W output now.
UHF repeater:
Checked all cables.
Fixed N-male connector on RG214 between duplexer and repeater in RX path)
Retuned duplexer (434.625 -0.79 dB / 433.025 -1.38 dB / 102 dB isolation)
Placed duplexer back.
Measured power and SWR:
Repeater output 30W SWR 1
After circulator 27W SWR 1
After duplexer 22W SWR 1 (With dummy load)
After duplexer 22W SWR 1.4 (With antenna)
Tested sensitivity direct on repeater (3.5uV)
Investigated repeater. In process of investigation sensitivity went down to 0.55uV, but lots of rain) Could not measure 12db sinad, but suspect it to be around 5uV (the by ear test).
Sensitivity was at 0.55uV at end.
Finshed around 14:30 and drove down.
Summary
More thinking will need to be done about Heliax state.
VHF Repeater
TX side: improved output by swapping out band pass filters (2.1 dB improvement, output now 15W)
RX side: removed 2 cavity bandpass filters (improved RX by 3.63 dB)
UHF Repeater
TX side: improved by 0.83 dB
RX side: improved by 4.7 dB
UHF repeater is not healthy.
TODO:
Investigate Antenna options VHF
Investigate why 1.4 SWR on UHF
Decide on Feeder
Think about linking
Service UHF Repeater
Meetup at gate (at tar road) +_ 09:00.
Drove up.
Measured Power and SWRs
Batteries 13.3V and 13.2V
Power Supply Unit right 26.64V
Power Supply left (DC to DC) 13.7V
Power Supply RHS against rack (DC to DC) 13.8V (Negative grounded on rack)
Between Duplexer and Heliax 10W SWR 1.4
Between T4002 and circulator 30W SWR 2
Between Circulator and Band Reject Filter 16W SWR 1.7
Between Band Reject Filer and Duplexer 13W SWR 1.4
Tested Heliax and Antenna
Used hand radio as source
Bottom 6W SWR 1.4
Removed antenna and replaced with dummyload
Bottom 6W SWR 1.4
Top 5W SWR 1
Reconnected antenna
Top 5W SWR 1
The 2 stage circulator was retuned to correct SWR problem (145.750 before -1.2dB SWR 2 after tuning -0.38 dB SWR 1) The first cap in circulator is suspect.
Bandreject (Notch) filter on 146.2375 was measured and the one nut was tightend
The duplexer was measured and retuned to get a beter insertion loss on 145.150 (before -1.95db after -0.74db) (One cable in harness was found to be wrong length and was replaced)
Wideband bandpass filter was measured. This was connected between cavity bandpass filter and preamp. Moved to be between circulator and bandreject filter.
Cavity bandpass filter was retuned for beter pass band. (before -5.71dB after -4.6dB)
Tested gasfet preamp (145.150 +16 dB)
All equipment was labeled with measurements.
Repeater sensitivity measured -0.4uV
Everything reinstalled and some final measurements
Between T4002 and circulator 30W SWR 1
Between ciculator and Wideband bandpass 27W SWR 1
Between wideband bandpass and band Reject filter 12W SWR 1
Between band reject filter and duplexer 11W SWR 1
After duplexer, just under 10W
Sensitivity after duplexer 0.3uV
Tested UHF dipole antenna on side of building (good strong signal to 438.800)
Cleaned up and drove down +_ 15:30.
Summary
More thinking will need to be done about Heliax state.
TX side: losses was improved and corrected, but with the introducing of the wideband bandpass in the correct place, no power was gained.
RX side: removed wideband bandpass (2.2 dB improvement), returned cavity bandpass (1.1 dB improvement), retuned duplexer (1.2 dB improvement) Total 4.5 dB improvement
TODO:
Investigate Antenna options
Decide on Feeder
Think about linking
Retuned Wideband bandpass Filter to have less loss on 145.750 (currently -2.7db)
Move preamp before cavity BP filter. (This would just make more sense to amplify, before filter)
Remove one can from Cavity BP filter, retuned for 145.750 and replace wideband BP filter. (Will make about 1.2db more sensitive on RX and about 2dB less loss on TX)
Service UHF
On 23/24 July the Motorola repeater was damaged in a storm. It is suspected that the repeater was damaged by static from lightning.
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:
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.
On site around 10:00
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.
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.
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.
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.
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.
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:
Everything was packed up and returned home. Home around 13:00 and unpacked by 13:30.
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.
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.
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.
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.
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.
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.
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.
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
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)
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.
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.
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.
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
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.