|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.
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.
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 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.
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.
Video of the installation of the repeater housing, antennas and tower work
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 VK6LZ & Trish VK6QL transporting power cable & 2 metre antennas
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.
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.
Installing repeater housing - Joe VK6ZTN left and Trevor VK6MS
Joe and Trevor still working away
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 VK6LZ, hacking through the limestone for the cable run
Glenn VK6ZGT.....Running the power cable
Job finished and it was coffee and cake...Rottnest
This is a receint photograph taken off the Nearmap web site..All looks to be there
Top of Rottnest tower November 2010....Photograph John VK6UP
Housing for Rottnest repeater November 2010....Photograph John VK6UP
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
WESTERN DIGITAL NEWS for 18/11/90
and reports on the Rottnest construction weekend on 11/11/1990.
Western Australian Amateur Digital Communications Association
-------------------------------------------------------------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.
Secretary.P.O.BOX 425. CANNINGTON W.A. 6107. VK6QL @ VK6BBS
The current Membership Subscription is $10. per annum.
MEMBER NEWS FOR SUNDAY 18th NOVEMBER. 1990
GENERAL MEETING WEDNESDAY 5th DECEMBER 1990
VK6BBS/VK6ZML - BULLETIN BOARDS - USERS SURVEY - OCTOBER 1990
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.
THE REPEATER GROUPS "ROTTO" WEEKEND
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.
AMATEUR TELEVISION "FORMAL GROUP" MEETING
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.
OTHER RADIO CLUB MEETING DATES
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
END OF WESTERN DIGITAL NEWS 18/11/90
Transmitted by VK6TTY @ VK6BBS.#WA.AUS.OC