Maintenance Hawequa 20160709

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Jan (ZS1VDV) and a friend departed to Hawequa around 09:00

Arrived on site 09:45, little to no wind and about 5 degrees.

View towards Worcester from Hawequa

View towards Worcester from Hawequa

Started to try reproduce the current interference problem. Could only get it to happen when our repeater started to transmit first and the the commercial repeater in our hut second.

Next step was to measure our duplexer and bandpass filter (RX) and second harmonic filter after the circulator. I did not check SWR, because this was checked on the previous visit. Nothing could be found wrong with our filters and duplexers. (The bandpass filter on RX does add about 2dB insertion loss on 145.050 Mhz and will need to be replaced as this sets our total insertion loss for the duplexer and bandpass filter to about 4 dB).

145.650 Duplexer (Sinclair Q202)

145.650 Duplexer (Sinclair Q202)

Bandpass filter in RX path

Bandpass filter in RX path

Then scanned with a SDR spectrum analyzer. Found that the commercial repeaters RX and TX frequencies was labelled wrongly. Could not find any strange signals. About -85 dB filter on the TX frequency of the commercial repeater in the input path.

SDR Spectrum Analyzer

SDR Spectrum Analyzer

So the only conclusion was that the interference is a mix of our output signal, but mixed with the commercial repeaters signal. The second harmonic filter was replaced by a bandpass filter to make sure that our transmission path is clean.

New bandpass filter installed

New bandpass filter installed

This did not solve the problem.

For now removed the CTCSS on TX path. Will check in with commercial repeater owner to add a circulator to their repeater.

Resolved the battery voltage that was reading wrong. The sense wire got damaged and was replaced.

Left for home around 13:50, about 9 degrees.

Arrived home around 14:30

Maintenance Hawequas 20160703

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Jan ZS1VDV, Dirk ZS1VDB and Paul ZS1V departed Stellenbosch for the Hawequa 145.650 site at about 9.30am on Sunday 3 July.  It was sunny but cold, with a light dusting of snow on some of the nearby peaks.  Dusting of snowJan applied a filter to the cooling fans and a modification to the 2m repeater linking cable.  The latter being necessary as part of a correction to the incorrect emphasis on audio from the links to the 2m repeater.  The change necessitated a complete re-alignment of the audio through the link controller.

Soldering in a tight space

The SWR on the 2m antenna system was tested and found to be satisfactory.  An inspection of the antennas and the coaxial feeds also found everything in good order.

A source of interference on the 2m repeater was also identified and this will be taken up with the operator of the equipment in question.

Ice on the rocks

The team returned to Stellenbosch at about 2.30pm in dire need of hot coffee.

Paul
ZS1V

Repeater Status Reports 20160614 & 20160621

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Yup, you read that right. I’ve been more than a little busy lately, still am, and forgot to post the weekly reports here on the website. Sure, they went out on email but that’s only half the job. So, bundled together in a single posting we have 2 reports! Oui, deux rapports, twee verslae, zwei Berichte, dois relatórios!  🙂

Enjoy!

WCRWG_Status_Report_20160614

WCRWG_Status_Report_20160621

Maintenance Jonaskop 2016-06-05

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On Sunday 5 June, the team consisting of Jan ZS1VDV, Paul ZS1V, Mike ZS1TAF, David ZS1DDK and Andre ZS1AN headed to Jonaskop to attend to a number of issues at the 145.675 repeater site.

It was a sunny, but cold day at around 1C when the team arrived, but warming to a comparatively pleasant 7C by the time we left at around 5pm.  A light breeze aided in keeping everybody’s hands cold.

Jan ZS1VDV selecting the correct scalpel

The following tasks were completed:

  • Replacement of a faulty speech chip in the controller and re-enable temperature and voltage measurement macros
  • Correction of the audio emphasis for audio from the links to the 2m repeater
  • Realignment of audio talk through levels
  • Installation of a second backup battery
  • Reinstallation of the VHF ferrite circulator and harmonic filter after the latter was retuned
  • Improve station grounding
  • Install vent covers on the equipment housing
  • Investigate and correct interference problem on the 2m repeater – VHF SWR was high (> 2.5)
Mike ZS1TAF and Paul ZS1V attending to the VHF SWR

Mike ZS1TAF and Paul ZS1V attending to the VHF SWR

At the end of the day, a light crackle in the repeater tail was traced to the audio mixer in the controller.  This was also corrected.

FLTR Paul ZS1V, Jan ZS1VDV and Andre ZS1AN

FLTR Paul ZS1V, Jan ZS1VDV and Andre ZS1AN

Photo credit: David ZS1DDK

The team arrived home again around 19.30.

Paul
ZS1V

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.

Repeater Status Report 20160524

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Hi again, people!

I’ve scoured my inbox for any extra news to bring you this week but it seems the best I can do is to report that the link system seems to be working exceptionally well. For example, I was listening to ZS1MJJ and ZS1OKO chatting this evening and it sounded really nice. 🙂

Other than that, not much to add. Here’s the weekly report for your collection 🙂

WCRWG_Status_Report_20160524

Repeater Status Report 20160517

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Greetings, folks!

Well, well, well… what a lot of work has been happening! The Hanskop site has seen a load of activity the past few days what with tower happenings and moving antennas and the UHF link to Jonaskop has never been better! Check out the report on the website for details 🙂

That said, here’s the status report for this week, for your reading pleasure. Enjoy! 🙂

WCRWG_Status_Report_20160517

Edit: New report version with the status of the link from Hawequas to Hanskop corrected.