An important piece of equipment in Terrier Hunting & Earthwork is the locator system. We have a few types. The Deben LRT system works fine, however it is now discontinued as far as I know. The state of the art for Terrier locator systems is made by Bellman and Flint. Both are products of the UK where Earthwork with Terriers originated. Both systems are durable and functional, but the B&F system is my preference. The B&F locator collar can be used with a standard avalanche transceiver, if the locator box is unaffordable for you. The avalanche transceivers are available from several manufacturers, and can be found used on EBay.
Another type of system I have is a Garmin Alpha, with a TT15Mini tracking/training collar. This system is ideal for hunting above ground in areas of rough terrain or thick brush. It was not long after I purchased this system that I found myself needing it. Not only did the GPS help me orient myself in the right direction, but it helped me find a dog that was 900 + yards out, lost in a marsh.
While there are a few hunters who hunt without collars, it is not recommended. Responsible dog ownership dictates using the proper safety equipment when engaging in this, or any canine sports.