Fox Hunt Transmitter Kit

If you enjoy hidden transmitter hunting and are looking for a small inexpensive "fox box", "bunny box", or "fox transmitter" or what every you want to call it you have come to the right place!.

This tiny transmitter (about 2 inches by 4 inches for the board) includes a PLL synthesized transmitter and a simple to setup and use controller. All for less than you might expect to spend on just a fox controller.

Features

• PLL Synthesized FM transmitter capable of operation anywhere in the 2 Meter band. (Easily modifiable for operation in other FM bands eg. 6M or 440)
• Three preset channels are field selectable!
• Morse ID Easily programmed through any terminal or terminal program.
• Programmable "hang time" between ID's. up to 4 minutes.
• Programmable "off time" between transmissions of up to 4 minutes.
• Field programmable delay start of up to 2 hours allows hiding the transmitter before the hunt starts.
• Only 150ma power consumption when transmitting 1/2 watt.
• Frequencies and ID are stored in non volatile memory.
• 6-18 Volt supply range.
• Instruction manual including suggested modifications.

Want more information? Download the PDF file of the instructions 20 pages, about 122K bytes. (updated 6/28/1999 with more notes!) Need even more info? See the FAQ below.
If you want to make your own boards look here for the gerber files.

The first set of fox kits is Sold Out

• Approximately 5 Watt optional PA stage
• Better grounding
• Options for a voice recorder

On a recent hunt the prototype was hidden in a bush!

Unfortunately there are no pictures from the more recent hunt (June 5, 1999) Where Two of them were hidden. The First, the hard fox, on 146.415 was hidden at the intersection of Page and Kato Rd in south Fremont. This fox was hidden in a ditch next to the road and on a poor antenna. The initial bearing from the start point and weak signal indicated that it was much further away in Alviso, so most hunters drove past it on the highway and needed to double back.

The Second fox the easy fox, on 145.565 was hidden in the parking lot of Mission Pizza at Central Ave. The Jpole Antenna was wire tied to a freeway fence and had a stong signal up and down the freeway. Most hunters came up the freeway from the hard fox and drove past it and had to loop off the freeway at Thornton.

The Easy fox was deployed first and the timer function was used to set a delay start of 1 Hour. I actually set the timer at home and drove to the first hiding spot. I arrived at the second spot, the hard location about 37 minutes before the start time, and deployed the hard fox with a 37 minute delay. This gave me plenty of time to show up at the start point.

It was fun to watch the hunters scratching their heads and taking carefull bearings on the hard fox. Many of the hunters needed to climb the hill at the start point, where the signal did not improve much, making most hunters believe the fox was quite far away when infact it was only about 2 miles away.

Most of the hunters had found both foxes and ordered Pizza by 7:00. Great fun was had by all.

Fox transmitter kit FAQ

Q2: Why is it so inexpensive?
A2: The first batch of kits are offered at parts cost, so fellow hams can experiment with it and suggest improvements. The initial design was done with an eye on cost looking for the lowest cost set of parts to build the fox. After the first batch is exhausted all the suggestions will go into the next rev. Please note that ALL of the kits built so far have worked fine. For helping with this experiment you get to provide input to the next round and are eligible to buy the next kit at cost as well.

Q3: How long does it take to build the kit?
A3: Depending on your experience it is build-able in an afternoon.

Q4: How complete is the kit?
A4: The kit is basically complete, you need only supply a battery, (optional power switch) and an antenna. There are a few coils you need to wind out of the provided wire on a screw you provide as a form. A BNC connector and short piece of RG-174 are included. Note that you will also need an RS232 level converter for bench programming.

Q5: What special equipment is required?
A5: I used a meter, oscilloscope, spectrum analyzer, antenna analyzer and a frequency counter when I built the first ones. However you could get away without most of that since the turning of the VCO does not need much tuning. You could use a power meter to tune the low pass filter.

Q6: What if I have problems?
A6: I would be happy to help via email or come by the garage and I'll help you tune it up.

Q7: What the deal with the RS232 Level converter, Why is that not included?
A7: The level converter is buildable out of a few parts you likely have around. If you have an adapter for a comupterized radio you may already have one. It is not included since I know there is little need for it. You only need it when you are "bench programming" the fox, and you only need one, no matter how many foxes you build. The instructions include a simple schematic for about $1.00 in parts, that you can scratch build in a few minutes.

Q8: What are the main features of this fox?
A8: The basic features are:

• Low cost.
• Integrated controller and transmitter.
• Field selectable start delay.
• Field selectable choice of three preset channels.
• Preset channels user programmable in 2M band, 6m, 220, or 440 with mods.