On Monday 1 June 2020, Jan ZS1VDV and Paul ZS1V visited the Hanskop 145.600 site to assess the damage to the equipment after a burglary that occurred over the weekend prior.
The perpetrators ripped out and made off with the battery charger, multiplug and 220V power lead. Temporary repairs were made and plans put in place to return and complete the restoration.
Category Archives: Repeaters
Hawequa Maintenance 20200531
An investigation was done to get more information for the pause in voice feedback on the UHF link repeater.
Reference voltage was re calibrated for more accurate temperature and battery sensors.
Bottelary repairs 20200530
On Saturday 30 May, John ZS1EQ, Paul ZS1V and Jan ZS1VDV visited the Bottelaryberg highsite that hosts the 145.575 DSTAR and 438.300 multimode digital repeaters. While both repeaters were operating correctly, the internet link to the site had been down for several months, limitting the utility of these repeaters.
The internet link was re-established and a general health check of the site was performed. The gateway unit for the VHF DSTAR repeater was found to be faulty and removed from the site. As a consequence the UHF multimode repeater is now fully functional, but the DSTAR repeater is not linked to the internet.
A battery switch over and low voltage cutout unit on the backup batteries was installed.
Jonaskop Maintenance 20200524
Jan, ZS1VDV znd Ralf, ZS1RK visited Jonaskop toe investigate why the link controller was down.
It was found that a power plug was intermittent and repaired.
The reference voltage for the temperature and battery sensors was re calibrated.
Jonaskop maintenance 20200509
On Saturday 9 May, Jan ZS1VDV and Ralf ZS1RK visitted the Jonaskop 145.675 repeater site. High wind conditions prevented close up inspection of the antenna connections on the tower, but the SWR of all the antennas were checked and found to be good.
The VHF repeater squelch was adjusted. The audio levels were re-aligned and one coax connector was seated correctly.
Hawequa Maintenance 20200425
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.
Kanonkop maintenance 20191026
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
Kanonkop maintenance 20191019
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
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.
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.
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.
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.
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:
- 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
Everything was packed up and returned home. Home around 13:00 and unpacked by 13:30.