Category Archives: Piketberg

Pikerberg Maintenance 2021-05-18

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It was an early and crisp morning of 7 degrees when Mike Kellet, ZS1TAF, and Mike Taylor, ZS1MJT, met in Tableview and departed for the 145.625 repeater high site in Piketberg.

The plan for the day was to replace the dipole antenna and try see where the problem was with linking the 70cm and 2m systems.

The planning started a few weeks before the 18th. New equipment needed to be purchased and a plan was put in place to get access to the Sentech site. On Monday 17th, ZS1TAF collected the new dipole and ZS1MJT got a crash course on how controller and laptop interface worked, or didn’t.

We left Tableview at 07h00 and enjoyed the beautiful sunset en-route.

09h15 we arrived at the high site and started preparing equipment for the climb up the tower. Trying to identify the antenna from the ground was rather challenging, but ZS1TAF eventually made it to the 2m 4 stack and started work on cable checking and testing (SWR was around 1.5). He found the old joint to the antenna to be damaged and brittle and water had found its way into the socket.

At just under 80m up the tower, the wind proved to be a bit of a contender, but Mike, as resilient as he is, trudged on relentlessly and eventually got the job done. The old antenna was put back and the SWR retested, reading around 1:1.

While Mike was working on the antenna, Mike ZS1MJT, did software checks on the controller. Software was updated and the programming was reloaded.

We tested signals and got positive feedback from fellow Hams in Cape Town.

We departed site around 12h45 and headed back to Tableview. We were back at Tablwview around 14h15.

A huge thank you to Jan ZS1VDV, Rassie ZS1YT, Sybrand ZS1SJ and Paul ZS1V for arranging and coordinating the successful visit.

Maintenance Piketberg 20200627

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Michael ZS1TAF did a quick on site diagnosis on 26 June 2020 and found that the controller needed reconfiguration.

Paul ZS1V and Jan ZS1VDV went to Piketberg on 27 June 2020.

The controller was reinitialized, firmware reloaded and reconfigured. (Last done 3 November 2018)

The VHF antenna system was found to have a 2+ SWR, and needs servicing.

Piketberg Visit

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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.

Maintenance Piketberg, Hawequa and Bottelary 20180113

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Jan (ZS1VDV) and John (ZS1EQ) did a round trip to service 3 sites.

Started to load the bakkie 07:00.

Left Stellenbosch around 08:00 and reached Piketberg by 09:45

At the end of 2017, the Piketberg VHF repeater was removed.  The repeater was serviced by Verstay.  The final transistor was replaced.  A replacement duplexer was prepared during the week. The duplexer was swapped out and VHF repeater reinstalled.  SWR between duplexer and VHF radio was 1.2 and between the duplexer and antenna 1.3.

Left Piketberg 11:15 and was on Hawequa at 12:45.

The 10 amp battery charger was swapped out for a 7 amp battery charger.  The 10 amp is designated to go to Hanskop.

Left Hawequa 13:45 and reached Bottelary at 14:45.

Removed the UHF DMR repeater for service.

Back in Stellenbosch and unpacked by 16:15.

Maintenance Piketberg 2016-05-28/29

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ZS1VDV went to Piketberg on Saturday to resolve 3 issues.

  1. The power drops almost 1 second after transmission starts
  2. Add filter to link radio fan
  3. Correct emphasis settings on radios

This was suppose to be a quick 2 hour visit, but again turned out to be much more.

The morning started around 09:00 on site.

The first step was to investigate the circulator as it was suspected to be the reason for the power drop.  After checking the circulator and 2nd harmonic filter with a mobile network analyzer they where found to be in order. (about 0.5db insertion loss on circulator and a 40db filter on the 2nd harmonic).  It was then found that the duplexer was causing a 1.7 SWR on the TX path.  This was very strange because the duplexer was tuned on last visit.  The duplexer was removed from the rack and rechecked and found that the possible cause for the hi SWR is wrong length linking cables between the cans.  They only onsite solution was to “play” with the tuning of the duplexer (the result was that about 10db isolation was lost).  This is not optimal, but would still work.  The SWR now was 1.1 between the duplexer and circulator.  This however did not take the power reduction away.  The last step was to test the repeater on its own with an SWR meter and dummyload.  No SWR problem, but the cause for the power reduction was found.  The internal filters of the repeater needs to be re tuned and this cannot be done on site.

The filter was added to the fan of the link radio.

Emphasis settings was changed on the link radio and link cable updated on the repeater.  Audio was aligned.  At this stage it was about 13:30 with no water or food, this became a very long day.

On Sunday ZS1VDV returned to site to recheck the audio alignment and a few small tweaks was made.

TODO:

The repeater and duplexer needs to be swopped out.  The repeaters filter re tuned and the proper length linking cables for the duplexer made.

Maintenance Piketberg and Hawequa 2016-02-21

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ZS1DDK and ZS1VDV started just past 05:00 in Bellville.  Loaded all equipment and left Stellenbosch 06:00 for Piketberg.

Arrived 07:45 at Piketberg Site.

On Inspection 3 main problems was found:

  1. There is a local signal creating interference on the VHF Repeater
  2. The controller was set to key the link on COS, with the problem that this was too often.
  3. The duplexer was not tuned well enough.

Remedies:

  1. The SQL of the VHF Repeater was set to 0.25microVolt.
  2. The controller was set to key the link on the presence of CTCSS(PL) and COS(SQL).
  3. The duplexer was retuned.

Other maintenance:

  1. The circulator was installed between the VHF repeater and duplexer.
  2. The controller FW was updated.

Left Piketberg site around 11:30.

Quickly had lunch in Wellington.

Arrived at 13:45 at Hawequa.

Problem:

  1. UHF Repeater was not TXing.

Remedies

  1. The repeat setting on the controller was in an inconsistent state, this was due to deactivation which was done 15 Feb to protect the TX radio.  The setting was deactivated and the reactivated.

Left Hawequa site around 14:15.

Arrived 15:00 in Stellenbosch unpacked.

Finally got home at around 15:45.