VK1 Fox Hunt Report for Thursday 7th December 2000.

This Hunt took place in Weston Park Yarralumla starting at the Maze carpark. The fox was Neil VK1KNP.

The Fox went on air at 6:45 pm and only one hound was at the meeting point. John VK1ET set off on foot followed by Neil VK1KNP who decided to test an antenna and sniffer that was part of Tom VK1BUDs deceased estate. Although Neil knew the location of the fox, normal techniques with TOM's antenna and the hand held did not work until we figured out it was a null type antenna.

Two equal length folded dipoles connected antiphase with same length matching sections. Even having figured out the principle did not help greatly as there is no front to back discrimination of the signal.

The fox had been placed on the far side of Yarralumla Nursery and we encountered the chain mail fence which appeared to be radiating the fox signal. This further confused the readings out of the Null antenna. As murphy's law would have it, we picked the long way around the fence ending up 1/2 way back to the starting location before clearing the obstacle at the lakes edge.

After about 1/2 an hour the fox was located in a heap of garden mulch by John. Neil was still trying to figure out the operation of Toms sniffer at this time.

Tom's sniffer is an amplified tuned diode detector circuit with a large 1 ma analog meter. The meter works well at showing the nulls but it takes a bit more practice to interpret the peaks.

John took the fox and hid it nearby, while Neil retuned and looked at the calibration of the sniffer. Then Neil used Tom's equipment to find the Fox. All was going well with Neil following a strong null until he realised that he was DFing Black Mountain Tower, not the Fox. A quick retune of the sniffer yielded multiple null directions, some towards Black Mt and others slightly divergent. The divergent signals were followed and after a big spiral in on the fox location a mysterious heap of cut grass below a tree was investigated, But Alas No Fox! Further Dfing showed the fox to be up the tree. Neil had been fooled by the obvious red herring John had placed.

It was found that pointing the folded ends of the the dipoles of the null type antenna directly at the source causes the null to disappear. This can be used in the near field to determine if the fox is up or down.

Finally John had a try of Tom's equipment after Neil re-hid the fox. Similar problems with Black Mt were experienced drawing John well off course. Once John was within 40 m of the fox he began to get better readings leading him to the base of a tree. After searching the grass, John found it hard to decide if the Fox was indeed up the tree, however after some careful Null replotting he determined it had to be in the grass, and this time found the Fox.

Neil and John retired for a BBQ after the 3rd Hunt.

This was probably the last Hunt for this year, although if there is serious interest on the reflector I may schedule another one before January 2001

All the best for Christmas

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