Digital Repeater Build Day

On Sunday 19 February 2017 a digital repeater build day was held in Stellenbosch at the QTH of Jan (ZS1VDV).  The result was that there is now three home brew (MMDVM based) repeaters running in the Western Cape.

Digital Repeater Coverage as of 20 February 2017

In June 2016 the first build process started. Jan(ZS1VDV) and Paul(ZS1V) reached out to Ronald(ZS6RVC) and Johan(ZS6JPL) for some help and learnings. Johan provided ZS1VDV with a single PCB for an SP8NTH v6 shield. The orders was placed for Raspberry Pi’s, Arduino Due, SP8NTH v6.1 PCBs, components and Nextion screens.  ZS1VDV started to collect duplexers and radios.

SP8NTH v6.1 1st production

10 complete SP8NTH v 6.1 PCB was assembled and 7 was shipped up country.

In September 2016 the first proof of concept repeater was build by ZS1VDV. The next step was to design an produce a case that can be used on a highsite. This was completed early November 2016.

Stainless Steel Case

In January 2017 the finer setup and software configuration was resolved.

The next step was to build more repeaters.

A repeater that was build

ZS1MTF, ZS1BSD and ZS1VDV was involved with the build day. It started the morning at 09:00 with a quick recap of what digital repeaters are, what they are made of and how they work. Then two repeaters was build and configured.  The are on temporary wooden bords to keep costs down.

Currently there are three UHF repeaters running in the Western Cape that are DMR and DSTAR capable. The WCRWG is in process of moving a VHF DSTAR repeater and a UHF MMDVM repeater to a high site. This will improve the current coverage area.

Hermanus maintenance 20170212

David (ZS1DDK), Jan (ZS1VDV) went to do some maintenance on the Hermanus repeater.

With the last installation of the repeater it was found that the repeater rf sensitivity was not what was expected and needed to be corrected.

The weather was on and off with rain, the same as installation day, which did not make it fun.

Rain, not fun.

Started 06:30 in Bellville.
Pickup and pack equipment in Stellenbosch 07:15

Equipment packed

Left Strand around 08:00
Arrived on site 09:15.
Debug repeater sensitivity. In the process to realign the front-end, it was found that one of the 4 notch filters tuning pots need to be replaced as it was damaged.
The spare repeater was installed, audio aligned and link controller reconfigured for new repeater.
Did some testing with Sam (ZS1OR). The spare repeater is better, but still some areas need to be looked at.
Left site around 11:30.
Extended the power supply power lead with 2m.
Got some “quick” lunch on the way back.
Unpacked at Stellenbosch 14:30.
Back in Bellville 15:00.

Hawequa maintenance 20170128

Paul ZS1V went to the Hawequa 145.650 repeater site on Saturday morning 28 January, to diagnose a fault that was causing the link to operate in one direction only.

The effects of the recent fire were evident.  The veld had burned on both sides of the access road and to within 1m of our building that houses the repeater.  Fortunately, both our building, tower and the area in between where the coaxial cables are in the cable tray, were spared.

The destruction was quite wide-spread.  The poles supporting the electrical feed to the site have been burned and will likely need to be replaced.  For now, the power is still on.

Some diagnostics on the link controller were done and some settings adjusted.  The link is functioning correctly again, albeit still with slightly misaligned audio.  This will remain the case until firmware fix is provided by the link controller suppliers, enabling the return to the required configuration.

Link Installation Hermanus 20170115

ZS1TAF left home at 07:00. ZS1DDK, ZS1VDV, ZS1V and ZS1OR were collected and all the equipment was loaded in 2 vehicles.

The team arrived on site at about 09:45.

View

Unpacking

The weather was windy, misty and there was some rain to complicate matters. The team all got stuck in and many of the tasks were executed in parallel.

Raining, ZS1TAF sealing new UHF antenna, ZS1V keeping rain off ZS1VDV tuning the duplexer

The first step was to confirm the correct SWR on the current VHF installation.  This was found to be an acceptable 1.2:1.

The previous repeater was removed and the hut cleaned out.  A Webb HD400 UHF dipole, fed by half inch Heliax and an LMR400 patch lead, was installed with lightning protection, for the link to Hanskop some 40km away.

ZS1TAF sealing the UHF antenna with ZS1OR

The duplexer was retuned which improved the insertion loss from 3 dB to 1.5 dB, and the rejection from 65 dB to 82 dB).

145.725 duplexer results after tuning by ZS1VDV

The UHF power output was measured at 2W and SWR on the antenna system after installation at 1.1:1.

As with many of the WCRWG repeater installations, the new link controller installation includes inside and outside temperature sensors as well as a DC voltmeter that can be queried by sending DTMF codes.

The repeater power output was measured at 10w after the duplexer.  Due to local noise levels, the squelch of the repeater had to be tightened somewhat.

The team left the site at about 13:00 and everybody was back home with the vehicles unloaded by around 16:00.