This information correct on the 2th October 2012.
Any queries address to:-
Repeaters,  DARC, 17 Brownlee place, Bluff,  4052. Telephone: 031-4677357.

The zu9pkp repeater is one of the 5 repeaters originally licenced early 1970. Amateur repeater. (voice) zu9pkp. Licence number:418-312-9 region code:20886 allocation:0026

Frequencies. Rx 145,050/tx 439.00 mhz. This repeater was converted to 12,5khz channel spacing when the latest regulations required it.

Woodlands water tower.  Gps: 30:51:00 e 29:55:00 s. Kenyon howden road.

Rx. Storno type 614.   +   uhf tx storno type 661. Frequencies. Tx 145,650/rx 438,350 mhz   Bluff water tower.   Gps: 31:00,7 e 29:55,6 s. Bluff road.

Tx. Storno type 614 + uhf rx storno type 661. Power output 10 watts.

Note: split receiver and transmitter. Vhf receiver on woodlands tower, transmitter 11 kilometers away on the bluff water tower.  Audio and switching feed between the two sites by uhf, frequency 438,350 mhz. Power 2 watts.

Additional uhf receiver port installed at vhf transmitter site for bulletin and other facilities  . Input frequency allotted 438,450 mhz. This repeater is remote controlled as per licence req.  Requirements,  (on/off etc.)By zvei tones.

Responsible person: l. De bruin. Zs5lp.  Ph: 031-4677357

Technical information.

The above repeater installations provided for low rf losses needing only 8 metres coax cables. A notch filter is necessary as a commercial repeater on the same site could cause intermod problems. The total rf loss in the system is however kept to just over 1,2db.  The vhf antenna, a co-linear, was specially designed for the repeaters for maximum radiation lobes as required in the hilly terrain locally, requiring signals above the horizon.  The receive station is 106 metres above sea level while the transmit station is 88 metres above the sea.  Both vhf antennas thus must fire 5 to 10 degrees upwards both at the transmit station and the receive station. A 4 element beam at each site beamed rx – tx is installed. Uhf operates at >2 watts.  The receiver has some unique designs by zs5lp incorporated.

1) the squelch system was redesigned to assist in eliminating interference prevalent at the high site on which the 650 repeater is installed.

2) the interfacing between the receiver and transmitter is also designed for conditions prevailing. 99% of the interference consists of pulses or amplitude spikes of short duration, thus a 1,8 second delay is incorporated in the switch on of the uhf to vhf transmitter site.

This makes the repeater a “sleeping system”. To activate the system, there are 2 options:

1. The operator will give his call sign twice,
2. Or a carrier exceeding 1,8 secs, thus switching on the vhf transmitter. Operation will be conventional, as long as the ptt is within the 7 sec tail..

The  tail, a carrier, of 7 seconds duration is installed. This serves many purposes.

A) if using a handheld or being mobile the tail (transmitter on) allows sufficient time for the operator to establish a “good” spot, by noting the “s” meter strength.
B) the unwanted noise, a hanging squelch, “kerchunk” caused by the rx/tx switching on/off,(with no tail,) systems is now eliminated and left till end of the tail when the repeater drops out.  This is important when operating on recording,  “intecnet” or similar nets.

Zu9qkb. (as soon as traffic demands this repeater an be switched on.)

This system also operate as a  split site operation as for 145,650 mhz. Uhf frequency allocated, 438,300 and extra port 438,500 mhz can be installed if required.

This system will be installed as per the 650.

**(refer correspondence and authorization of the allocation of 4 uhf channels with sarl band planner, for the vhf band planner co-ordinator during 1978.)

Amateur repeater (voice.) Zu9qkb
Licence number:416-313-7 region code:20886 allocation:0026
Frequencies. Rx 145,125 tx 145,725 mhz. Tx storno type 614. Rx storno type 614. Power output 10 watts.
Uhf shinwa. Uhf channels: 438,00mhz, with extra port 438,500 mhz.
Output power approximately 4 watts. Uhf 4 element beam antennas.
Converted to 12,5khz spacing.

Responsible person: l. De bruin. Zs5lp.  Ph: 031-4677357.
ZS5D. Unrestricted.
Licence number:420-170-1 region code:41803 allocation:0026
Chairman. Durban ARC.   Ph: 031-4677357.
Durban Amateur Radio Club Station.
Repeater keeper: Louis De Bruin.   ZS5LP.

**it was during 1977 that more repeaters were being installed at the montclair water tower. All of these were in the vhf band giving rise to inter-modulation problems.

The receiver @ 145,650 mhz being only 600 khz away – together with the commercial repeaters gave reason to investigate how to resolve this problem.

After much consideration it was decided to split the amateur 050/650 receive and transmit units. This was to be linked by using uhf. Easier said then done. The sarl band planner could not understand what i had in mind. The then vhf co-ordinator was not technically orientated.

The uhf band plan was obtained and the “link” band indicated that in the uk. Frequencies in the 438mhz section should be used for linking all type of repeaters. It was the following year that a new band planner was appointed, being john fielding zs5jf.

John was contacted and the good news – he agreed that linking as shown in the band plan was allowed. He suggested that channels should be selected and application made through john (sarl).

The uhf channels were monitored on storno uhf receiver modules and 4 frequencies was selected, having no interference on the receivers.  Application was made and within a few weeks permission was granted, (thanks john).

Permission was obtained for the second site, as shown in the information section, this in turn thank you steve pietersen zs5hp.

It did take a lot of experimentation to obtain the present results. The history of repeaters in Durban branch later, Durban club will feature in the history section of the website as soon the repeater item has been written up.