Rottnest mark 2

VK6ROT or VK6RAT....?


Rottnest Island, located 20km off the coast from Fremantle, is a holiday destination for many and WARG had for a long time considered it as a place to locate a 2 metre repeater. At the end of 1990 it almost happened.

Rottnest Sun set

Radio mast on left - wind turbine - light house

With the large Tic Hill and Busselton repeater sites long established, Rottnest could be an easy project it was thought. The FM880 design had been proven and would be the chosen repeater to go in at Rottnest.

The interesting aspect was that there was a 100' guyed tower already on a high point in the centre of the Island, that had been used for wind speed and direction information by the nearby large wind turbine. No other equipment was on the tower at all.

The Rottnest Authorities were asked for permission to use the tower and they accepted our application to do so. We even obtained permission to use 240 volt power from a nearby shed.

Testing the site

With access to the site, a coverage test was the first step. Rather than install VK6REE with all the requirements of filters etc a simpler idea was to use a dual band radio operating in repeater mode. Amateurs could cycle and walk around the Island using 2 metres or 70 cm to communicate via the cross band repeater. This set up could also be used to link to VK6RUF and then those on the Island could talk to other amateurs on the mainland. Both modes of operation were used and the Island coverage was given a good trial.

The coverage was excellent, even as far out at West End on the beach below the cliffs.

The design

Rottnest is isolated in terms of you just can't drive to the site. It requires a ferry of boat ride from the mainland to do the installation and future maintenance. Hence the design had to be simple and easy all round.

After much discussion the following design was decided on.....

No shed to house the repeater.
Repeater to be housed on the tower.
Low voltage (12v) power run from the shed where 240v power was available.
Two antenna split design.

The split antenna design should not require any cavities but if required they could also be mounted on the tower. By mounting all equipment on the tower vandalism would be made more difficult.

Rottnest repeater design

Rottnest repeater site design

Stage one Rottnest installation

WARG decided to install a repeater on Rottnest. The basic concept was decided, with the repeater mounted on the mast and using a split antenna design, fabrication of the parts began. At this point an FM880 repeater was not finished but the housing and 2 metre dipoles were constructed. Coax cable was obtained as was a long run of heavy duty 3 core mains cable. Not to carry mains but the 12 volts from a power supply to be housed in the nearby shed.

All equipment had to be transported over one the ferry or Trish's (VK6QL) sail boat, Sea Flight, which sailed over from Fremantle, and carried all the heavy items.

Video of the installation of the repeater housing, antennas and tower work

The small pictures below are video frame grabs and as such of poor detail but at least they give you some idea of the work done at Rottnest. The video is available soon.

Sea Flight

Sea Flight, later to sail around the World by David, Trish's son.

On arrival all items had to be walked or transported to the hill on bicycle, a distance of 3 kilometers. There are no private cars allowed on Rottnest, so getting to and from the site, as beautiful as the walk or bike ride is was of concern for maintenance.

Cliff and Trish

Cliff VK6LZ & Trish VK6QL transporting power cable & 2 metre antennas

Climbing Rottnest hill

The last few hundred metres by foot up to the Rottnest tower.

It was decided to also link the Rottnest repeater to VK6RUF for a re-broadcast of the WIA news. The initial design was for a one way only link that would transmit the news onto the Rottnest repeater and to later add the link back to VK6RUF for two way linking.

Fitting the repeater housing

Installing the UHF link antenna to VK6RUF Roleystone

There was much thought put into the design of the repeater housing. The FM880 would be placed inside the box from below into a small rack frame. The most important issues were keeping the rain out and reflecting as much heat as possible. During summer the box would be in direct sunlight. Air vents were on either side with a over hang to prevent rain getting in. The box is still there today as are the antennas.

The repeater housing

Installing repeater housing - Joe VK6ZTN left and Trevor VK6MS

box installation

Joe and Trevor still working away

The finished installation Rottnest

The finished tower work, 2 two metre antennas - UHF beam - repeater housing

The installation required two days and Trevor VK6MS changed the guy wires while others dug in the low voltage power cable from the base of the tower to the shed. Both jobs were difficult, Trevor did all the tower work replacing all the guy wires, with some ground help, while the rest used shovels and pick axes to dig a trench through the limestone.

Cliff Rottnest

Cliff VK6LZ, hacking through the limestone for the cable run

Running the power cable

Glenn VK6ZGT.....Running the power cable

Running the low voltage power cable

Job finished

Job finished and it was coffee and cake...Rottnest

Site today

This is a receint photograph taken off the Nearmap web site..All looks to be there

Rottnest tower top

Top of Rottnest tower November 2010....Photograph John VK6UP

Rottnest tower box

Housing for Rottnest repeater November 2010....Photograph John VK6UP

Rottnest low antenna

Rottnest tower lower antenna below repeater housing...Photograph John VK6UP

So why was there no repeater installed at Rottnest...? Firstly the repeater was never built and secondly there was growing concern that the maintenance required could prove too difficult and too costly. If the repeater operated with little or no problems then it would have been sustainable but with repeater problems at other sites the enthusiasm diminished and some 20 years later there is still no repeater on Rottnest.

With new radio technology, a very reliable repeater could be installed at the site. It would have to be solar powered and perhaps run at a low power, say two watts from a Hamtronics exciter. Linked to Roleystone it would be a valuable repeater on the Holiday Island.

The FOLLOWING is the W A A D C A
Western Australian Amateur Digital Communications Association
and reports on the Rottnest construction weekend on 11/11/1990.

  Western Australian Amateur Digital Communications Association
   Secretary.P.O.BOX 425. CANNINGTON W.A. 6107. VK6QL @ VK6BBS
     The current Membership Subscription is $10. per annum.



W.A.A.D.C.A. Meetings, held in the Meeting Room at Wireless Hill at 8pm  on  the first Wednesday of Every Month, General Meetings are   held  in  the  months  of  February,  April, June, August, October, December  and  the  Informal Meetings  in the alternate months of January, March, May, July, September and November.


During  October  I collected  the users list  daily, and can now make the following report

              BBS  ZML                       BBS  ZML                        BBS  ZML
Oct. 1st. 19      16 
 "    2nd. 20      15             Oct. 12th. 22   19               Oct. 22nd. 16   19
 "    3rd. 24       19               "   13th. 24   26                 "    23rd. 20   14
 "    4th. 18       17               "   14th. 19   19                  "    24th. 23   20
 "    5th. 23       19               "   15th. 23   26                  "    25th. 16   20
 "    6th. 23       17               "   16th. 23   23                  "    26th. 20   23
 "    7th. 22       24               "   17th. 13   17                  "    27th. 25   22
 "    8th. 18       17               "   18th. 20   14                  "    28th. 20   20
 "    9th. 22       22               "   19th. 20   26                  "    29th. 26   22
 "  10th. 14       13               "   20th. 24   19                  "    30th. 21   22
 "  11th. 17       17               "   21st. 25   22                  "    31st. 20   14

VK6BBS   TOTALS   = 640 = (20 users per day, average)

VK6ZML   TOTALS   = 603 = (19   "    "   "      "   )

It  should be noted that some, if not  most of the regular users check  a Bulletin Board  more  than once per day, and most users appear to check both of these boards on a regular basis.


Those of you  that have spent a weekend  away  with the Repeater Group  will know that  we work hard and then we party, well last weekend was just a little different, we decided that we were not "Mad dogs and Englishmen" and stayed out of the midday sun.

On Friday evening  Trish VK6QL set sail on "Sea Flight" her boat with  Fred VK6UR and  John (a relative) and the rest of her crew Joe VK6ZTN  and Robin and David her children,  for  a  leisurely jaunt down the river, from  the Royal Perth  yacht club  to  the Fremantle annex  for the night  and an  early start on Saturday, by the way, the boat carried the required equipment  (no I don't mean radio, flares and life jackets it has those anyway)  I mean the weather proof box designed by Will VK6UU and built for us by the Royal Flying Doctor Service workshops staff, the power cable three antennas, pick and shovel etc.

Saturday morning, rise and shine,  well  the sun did anyway,  we had a mad rush late nights and early mornings  don't go together went to bed about 3am up at 8.05 and on "Sea Flyte" the ferry in Perth at 8.55,  you didn't know  I could move that fast, neither
did I, Cliff VK6LZ and I were joined by Will VK6UU and some very important hand luggage, the video camera, an item never very far away at Repeater construction time.

Trish and crew  were joined by  Glen VK6ZGT, Chuck VK6ACB who is new in town (ex W6) decided to take a look at the group and took the  ferry from  Hillarys,  Trever VK6MS, Debbie VK6OJ and their three children came over on his work (tug).

10.45am the ferry docks at Rotto.  Will waits for his bike to be offloaded while Cliff and I head off to the bike shop before the rest of the crowd  got there,  Will  gets  the  key to Henderson House  our lodgings  for two nights  while I get the fresh bread from the bakery  and the milk,  the  boys  go to  check the site while the girls open the house.

What  kept us  out of  the  midday sun  "Lunch on the yacht" and very good  tucker too,  chicken salad,  and  then  a short motor burst  round to the jetty to unload the necessary equipment and  "off to work we go"

Trever  climbed  to  the top  of the mast  and fixed the receive antenna, then Joe joined him at about half way  for the transmit antenna  and  the  remote control beam  not  forgetting  the all important box  to hold the repeater,  on Sunday morning a party
went back to the site and buried the power cable etc.

You might be asking what all that had to do with digital matters well  the box  was designed  to hold two FM880's could the other space be for a digipeater, I wonder.


Brian  VK6TTV  is calling a meeting of ATV enthusiasts to try to formalise the group  and  would like  all interested amateurs to attend, the venue will be  the Audio/Visual department at WACAE. Person St. Churchlands  on  either  the 26th or 28th of November please contact him on Phone 09-387-6797.


Check with your group on the date for there Xmas meeting, most appear to be the first week in December.

W.I.A. General Meeting, Next Meeting 20th Nov.
W.A. Repeater Group. Next Meeting 20th Jan.
W.A. V.H.F. Group. Next Meeting 27th Nov.
W.A. V.H.F. Group's Fox Hunt. NEXT FOX 24th Nov.
Northern Corridor Radio Group. Next Meeting 27th Nov.
Hills Amateur Radio Group. Next Meeting 28th Nov.
Y.L. XMAS Lunch.  at SIZZLERS in RIVERTON, 12 Noon, 29th Nov.
YOUTH NET. First Sun.of every month. 8-30pm on 146.700.and 3.580

88 Christine  VK6ZLZ
Broadcast Officer

Transmitted by VK6TTY @ VK6BBS.#WA.AUS.OC