Sutherland Repeater maintenance 2019-06-11

Transmitter:

Output power:                  21.6W
Frequency error:              -315Hz
Deviation:                          1.49kHz

Receiver:

Sensitivity:                          0.683uV for 12.2dB SINAD (NOT CCITT weighted)
                                             @1.5 kHz deviation AT 1kHz
Squelch                              Could not be measured. Comms test set only goes down to 0.350uV

TX Filter unit:

RF power before filter:   42.63dBm (18.3W)
Return loss:                       3.4dB  !!!!!!(VSWR 1:5.23)
RF Power after filter:      34.3dBm (2.7W)
Antenna Return loss:      15.7dB (VSWR 1:1.39)

After tuning the filter unit, I got the following results:

RF power before filter:   42.85dBm (20.1W)
Return loss:                       23.2dB (VSWR 1:15)
RF Power after filter:      40.34dBm (10.3W)
Antenna Return loss:      15.7dB (VSWR 1:1.39)

RX Filter unit:

Measured loss at intended frequency:     20.6dB
Isolation at plus 600kHz                               Around 50dB

After tuning the filter unit, I got the following results:

Measured loss at intended frequency:     2.4dB
Isolation at plus 600kHz                               Around 50dB

Repeater without filters at high input RF level; 20uV 88.5Hz CTCSS @400Hz and 1.5kHz deviation @1kHz tone

Repeater without filters at low RF level; 0.683uV 88.5Hz CTCSS @400Hz and 1.5kHz deviation @1kHz tone

RF power going into the filters. Note poor return loss.

After tuning the filter. Note marker on 145.000MHz. Reference at the -10dB mark.

Results after tuning the TX filters.

Receiver filters before tuning: Reference is at the -10dB mark (-22.6dBm) indicating filter loss at 20dB.and off frequency.

Receiver filter after tuning. 2.4dB loss and on frequency. +600kHz isolation of around 51dBm

Repeater performance through both TX and RX filters after tuning filters.

The Site: Gentle reminder not to tamper……..

Conclusion:
I could probably get better results tuning the filters if I had the directional coupler with me. Maybe next time. I would have also preferred to have the manufacturers specifications to test against but did not have at the time. In my experience the repeater performs well according to what I measured. I tested the repeater from the town using a 5W hand held radio and got full quieting from the repeater with good quality audio. I there is someone who can test from the N1, some feedback would be great.

Report compiled by Neville Gleeson (ZS1NEV)

Site tested by: Neville Gleeson (ZS1NEV) and Deon Lamprecht (ZS1AFU)

Hawequa maintenance 2019-06-09

On Sunday a team of four consisting of David ZS1DDK, Mike ZS1TAF, Markus ZS1MTB and Rassie ZS1YT left home at 7h00 to meet at the site gate at 8h00. The purpose of the visit was to replace the 3 cable stays on the tower with new Stainless Steel cables, clamps and turn buckles.

Stay replacement

A 6m dipole was also fitted to the tower for future linking of a 6m simplex radio onto the repeater system.

Although quite a strong wind was experienced, the temperature on top of the mountain was a very cool 18o C.  Work started immediately with Mike and Markus climbing the tower and David and Rassie fixing the cable stays on the bottom anchor points. The team returned home by about 12h30.

6m antenna

The 6m Webb-antenna and Stainless Steel cable was donated by Rassie ZS1YT

The antenna clamps, cable ties and other hardware was donated by Mike ZS1TAF

Travelling to the site by ZS1TAF, ZS1MTB and ZS1YT was also donated.