We made our fox from a PicCon controller, a Yaesu FT-23 2 meter HT head and a 7 amp hour gel-cel. We run the HT at 1 watt output to preserve battery life and control heat buildup due to the 80 percent duty cycle most foxes have to endure for a few hours.
This is all placed in a 30 cal ammo can. A BNC bulkhead mount is on the side for the 18 inch whip antenna and counterpoise. An eyebolt through the latch was also added for locking and chaining to a tree.
The signal is easily detectable from 10 kilometers away, which is our standard hunt circle.
The PicCon allow the fox to be remotely controlled during periods when it's not transmiting and thus listening. It's worked great for us for about a year and the quickest way to get started.
73
Gary, K2GW