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Whitford 23cm Repeater. View from Whitford looking North-West on a fine winter's day (2003). Link to full size image 1760 x 1168, 116,554 bytes

An ATV beacon / Repeater is now running in the building at right, furthering the coverage that would be normally be blocked due to hills and ridges from the main ATV repeater.
Input 1 is 615.25MHz Vision, 620.75MHz Sound, from the main Amateur TV repeater, ZL1BQ.
Input 2 is 1284 MHz FM video, approx 15 MHz bandwidth, with stereo intercarrier sound at 5.5MHz and 5.74MHz.
The output is 1248 MHz FM video at 10 Watts into a 10 element panel array, directed across the bulk of the city. Coverage is across 90 deg approx, so a system of 2 panel arrays for receive and another 2 for transmit are being considered.

A disgruntled user who was sharing the site was asked by the property owner to vacate the site. He did so, but also cut down the main transmission pole seemingly out of spite. The police have been informed and are considering laying a change of 'Wilful Damage'.
This means that all the transmitters have no aerial system until we can beg, borrow or have donated a replacement pole for the antenna arrays. At present, the only active transmitter is ZL1UHF APRS UI-Digi, running on a temporary 5/8 wave whip. As the elevation of the site is good, it's coverage has not been affected too much.
Most of the antennae survived, being mounted on the front frame, as the pole fell backwards missing the equipment shed. The only antenna that ended up seriously being damaged was the 615MHz LPY pointed at the main transmitter site. It's driven elements and reflector were the first thing to hit the ground, and the boom ended up looking a bit banana shaped. It has since been straightened out and repaired thanks to Ken ZL1TD.

A 23cm QRP level beacon used to run at 1297.15MHz, with a morse ident of ZL1UHF. The aerial for this is a turnstyle inside a white plastic disc, on the pole above the temporary solar panel at the right of the picture. It has been taken off air until another site can be found for it, as it was desensing the 1284 MHz FM TV receive.

Grant ZL1WTT has a number of ATV experiments, a few of which are designed for the Whitford site in mind. Check out his home page for more...!

A 6m Beacon also runs from this site, with a Morse Ident of 'ZL1VHF Whitford RF73MB ZL1VHF', RF73MB being the grid locator. It's frequency is on or near 50.043MHz. It however suffers a bit from temperature drift, as it can get very hot up inside that building in summer.
*UPDATE* The beacon transmitter has been replaced with a commercial 'Tait' brand 'A' Band transmitter section set to 50.043MHz. The unit should be quite stable now.

The building is based on a 'garden shed', but with the panels screwed to solid wood wall frames which are then bolted to each other, and the roof section. This modular approach allows additional sections to be added, should the need arise.
An extra 50cm of wall height is planned to be added, between the roofline and the existing walls. A pair of extraction fans on the East (Left) and a remote controlled camera on the West (right) are also in the plans at some point, as well as thermal insulation to try and keep the heat down in Summer. The extra height will also allow a taller rack for more equipment inside the building, and tall people (i.e. me) to stand up straight in places other than the centre of the roof.

APRS Network Analysis

TinyTrak Stuff

Recently, well, over the last year I've built and used a TinyTrak in my car. It's worked quite well, and with the addition of the ZL1UHF APRS digipeater on the National frequency of 144.575MHz, has enabled me to see where I have been, sometimes in suburbs I'm not too familiar with.
The link above goes to a page with various TinyTrak bit and pieces, including screen grabs of the PCB I built with an on board MAX232 level translator IC. This was added as I noticed some PCs were unhappy with just 0 to 5 volt logic levels.
Another good reason for it to be added was that a WX-200 weather station interfacing to a WXTrak chip required the proper +/- RS232 serial voltages applied to it. The serial interface chip in the WX-200 is 'phantom powered', i.e. it is run from the voltages present on the RS232 side. With no negative voltages present, the WX-200 serial driver just couldn't pull it's RS232 output negative, the serial waveforms looked very sick and somewhat rounded on a 'scope. Consequently, the WX-200 and WXTrak just didn't talk to each other until the MAX232 chip was added into the circuit.

USB to Serial GPS Modification

When you have a TinyTrak, you really do need a GPS to help run it. I managed to scrounge several UBS GPSs intended for use with laptop computers, etc, and with a bit of tinkering, managed to extract the serial RS232 data from them.

Tait T700 Packet Mods

After using a 'lash-up' for a number of years for the APRS home station, I decided to mount everything properly and tidily, and use a radio with a little more grunt than the tiny hand-held that I had been using.
I also decided that having something on 70cm might also be useful too, at least for experimenting and not tying up the main 144.575MHz channel.
Thus 2 Tait T700 series radios that I had lying around not doing anything useful were pushed into service.
The 70cm version is a Tait T700TR (Trunking Radio) however it does have provision for a couple of non-trunking channels in memory.
Some minor mods were needed to change the audio in from mic level to line level, and obtain audio out from the mic socket.

Nicam Encoders

PI6DIG & co have built several Nicam Encoders which can be used with either the 5.85MHz or 6.552MHz intercarrier frequencies. Now seeing as commercial encoders are worth many thousands of dollars, and these ones go for much less than that, then if you are interested you should follow the link and see what interesting things there are at his web site..
Check out his Project Index page!!

All You Ever Wanted to Know About NICAM but were Afraid to Ask

New Zealand uses the Nicam 728 system to provide a stereo sound system.
Steven Hosgood BSc, Ph.D originally wrote this article, but it seems to have disappeared from the net. (Or maybe it's just that I can't find it anymore where it used to be.) Anyway, here's a mirror of his original article on Nicam. (and yes, it's still copyright to him...)

PAL B/G TV Channels

New Zealand used to use the PAL B/G system, information on which can be found here.

Auckland TV bandPlan

Auckland's channel usage and band plan are here.


For information on spam and BAIT go here here.


One of the things that Amateur TV beacon use are Teletext Pages.
These Philips SAA5050 powered pages have their page contents stored in EPROM.
Pin outs for various EPROMs are here.

Pace MSS100 Sat Rx as 23 cm Rx

The Auckland ATV group had access to some surplus Pace MSS100 sat receivers, and a couple of Uniden SQ500e receivers.
These can be used for FM-ATV reception with the aid of a pre-amplifier, and a x2 video amplifer (Hams use 1/2 satellite bandwidth, hence 1/2 volt video is outputted).
The link above goes into more detail.

Space Shuttle Views
Found some Space Shuttle stills, which seem to be still grabs from the cameras on / around the Space Shuttle.
Not sure how long they will last, so it may not work during some periods.

NZPO Type 100 phone circuit
In the days before Push-Button phones, New Zealand used to use rotary type phones, which are now starting to become collector's items. Finding circuits for them is now rather hard, so this scanned and tidied up one may be of use.

WX-200 Weather Station
One of my interests at the moment is a WX-200 Weather Station. It has the ability to measure-:

  • Wind Speed
  • Wind Direction
  • Air Temperature
  • Relative Humidity
  • Rainfall
    The information is shown on a local console, and the data is also available via a RS-232 port running at 9600 baud.


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