[size=medium]At the time I last show them in production, Bounty Hunter offered three (3) TR models, three (3) IB model (Induction Balance and are the same thing as the TR basically, but from an earlier vintage), the TR-1000-D which was a Discriminating TR, the Outlaw TR/BFO, and five (5) BFO models, The low-end Maverick, Bounty Hunter I, Bounty Hunter II, Bounty Hunter III and the Bounty Hunter Professional.
The Bounty Hunter III had a suggested retail price of $129.96 and was supplied with (I believe) a 6" coil. It had a large-size intensity meter, a Metal/Mineral tuner control, and a toggle for battery check.
The "Metal/Mineral" tuner is used to adjust for a "proper" motor-boating sound. This is done when the search coil is at the operating height.
You adjust it toward the "Metal" setting to locate coins, tokens, and gold and silver jewelry. There is no discrimination, as such, and the secret to peak performance is to maintain a uniform coil-to-ground relationship through the left-to-right sweep. You want to hear a somewhat comfortable motor-boating audio, and with a little practice you can determine what motor-boating speed (pitch) you need for best performance on targets and still an easily hearable beat-rate. What you listen for is an increase in the pitch (increased beat-rate) as the coil nears a metal target.
They lacked discrimination. They lacked the quick-response of a TR or IB design which makes it more difficult to discern subtle variances from a small and/or deeper target. If I recall, they required a battery pack using AA batteries. I don't mean this to sound too negative, but realistically and quite honestly, these older BFO types have very poor performance, lack the discrimination needed today for the abundance of modern-day, high-conductive trash, and have very, very little value.
While the one you have pictured appears to be in very good physical condition, most avid detectorists would be reluctant to pay more than $5 to $15, if that, for such a unit. I trust he got a good deal on it?!?
Monte [/size]