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.

Maintenance Hanskop 20161030

David (ZS1DDK), Andre (ZS1AN) and Jan (ZS1VDV) did maintenance on Hanskop.

Summary:
Removed UPS, replaced with battery and charger
Changed UHF repeater frequency (434.650 output/ 433.050 input)

Log:

Left Bellville 06:45.
Packed all equipment in Stellenbosch (07:45) (4 ammo crates, 2 x 15L storage boxes, 1 tool box(very heavy), Pelican case, comms test set, table and chair). (Takes about 1.5 hour to prep all equipment).
Collected battery and low drop out switch in Somerset West from ZS1V (08:00).
Collected key from ZS1YT (08:15).
Arrived on site at around 09:05. (15 degrees Celsius)

Unpacking

Unpacking

Removed faulty UPS (Battery banks is dead).
Installed new Victron Energy Charger.
Collect more equipment at N2 (Thank you Melissa (ZS1MEL) for driving from Stellenbosch).
Installed battery (donated by ZS1V).

Backup Battery

Backup Battery

Changed power wiring for new configuration.
Retuned UHF duplexer for new frequencies (434.650 output / 433.050 input).

Retuning Duplexer

Retuning Duplexer

Duplexer

Duplexer Results

Made changes to repeater configs.
Tested UHF repeater (1.5 SWR and 0.56uV sql)
Made changes to link controller.
Left site 14:23. (4 degrees Celsius)
Drop key at ZS1YT 15:15.
Unpack equipment in Stellenbosch 15:50.
Home in Bellville 16:30.

Maintenance Hawequa 20161009

ZS1YT, ZS1VDV and ZR1SWB went to Hawequa to investigate some errors after big Eskom/power outages/instability the last few weeks.

Vehicles Parked

Vehicles Parked

Wellington view

ZS1VDV and ZR1SWB

The morning started at around 07:00 with packing all tools and equipment. Left Stellenbosch around 08:00. On site at around 08:45.

First checked all voltage levels. It was found that the Benton Charger again was off and not charging the battery. The charger was replaced by an 10A Victron Energy charger which was donated by ZS1FX.

The link controller opened, and no damage could be seen. The audio paths was traced and all seemed in order. A complete firmware reload and configuration reprogram was done. At a stage last week the controller was rebooted numerous times(by power outages/spikes) and this caused the configuration to go faulty.

Left for home around 10:15.

Home and unpacked by 11:30.

Maintenance Hanskop 20160918

AGENDA:

Reinstall 434.600 Repeater and Duplexer
Research interference from 145.600 Repeater on commercial repeater
Research interference on 433.000
Research 145.600 dropout on input from Jonaskop.

Jan(ZS1VDV) left Stellenbosch 07:30.

Reinstalled 434.600 Repeater and Duplexer. Checked SWR (1.1).
Interference on 433 was determined to not be within the hut.

The interference from 145.600 and the commercial repeater was determined to be proximity. Moving antennas will be investigated. (Before tower fall it was 11m vertical, now only 1m vertical and 3m horizontal)

Could not replicate the dropout. Problem will continue.

Back in Stellenbosch 12:40

Maintenance Hanskop 20160904

Jan (ZS1VDV), David (ZS1DDK) and Andre (ZS1AN) started early at around 06:00.

We arrived on site around 08:15.

View from Hankop

SWR was tested on a few areas on the UHF repeater, duplexer and antenna.

It was found that the repeater has a permanent PA error and will need to be serviced.  The duplexer, harness is also suspect and have been returned for servicing.  The antenna and coax was all working fine.

The VHF main power supply was moved from UPS power to mains power.  This will now enable an short over beep on the VHF repeater when power is out on site.

Returned home around 12:00

Maintenance Hawequa 20160709

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

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

Maintenance Jonaskop 2016-06-05

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

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.