White’s Electronics Surfmaster DualField - Manual (Page 6)

6
Dry Sand Searching
The Surfmaster Dual Field operates on the Pulse
Induction principle. Unlike an induction balance
detector, it does not require any ground balance
adjustments. Most P.I. instruments must be swept
very slowly in order to achieve maximum depth, but
the Surfmaster Dual Field, does not. It was designed
to have a fast target response, so it can be swept
almost as quickly as an Induction Balance (VLF)
detector.
When you lower the loop to the ground, you should
not hear any change in the threshold tone. Mineral-
ized ground might cause a slight response, but the
S.A.T. circuit will compensate for it. Sweep the
loop from side-to-side and listen for any increase
in the threshold tone. Try to keep the loop level
about one inch above the ground. Any repeatable
signal, no matter how faint, should be investigated.
The loop needs to be in motion continually during
searching.
The Surfmaster Dual Field loop field is shaped
somewhat like a half-circle rather than the more
familiar “V” or funnel. For maximum coverage,
you should overlap your sweeps by at least 50%.
Targets can also be detected outside the edge of the
loop depending upon their depth and position with
relation to the coil plane.
The Surfmaster Dual Field has fast Self-Adjusting
Threshold. Once the threshold tone has been adjust-
ed, the S.A.T. system will maintain it. If you stop
the loop over a metal target, the S.A.T. will tune it
out and return the detector to the threshold tone. If
you move off the target, then back on, the detec-
tor will re-tune giving a response. For this reason,
the loop must be kept in motion while detecting or
pinpointing a target.
Operation
Chapter 4 Surf Dual Field Operation
Background
The Surfmaster Dual Field has been enhanced with
increased performance over past Surfmaster PI
models. It is a high-performance user-friendly metal
detector, waterproof to an underwater depth of 100
feet, operating on the Pulse Induction principle. It
is capable of extreme detection depth on coins and
jewelry in salt water and mineralized ground. In
the past, P.I. metal detectors had to be swept very
slowly for maximum depth and they had very poor
sensitivity to copper-nickel coins and gold. They
had manual tuning which was critical to adjust and
prone to drift. Most used a VCO or "fire siren" type
of audio tone which changed from a low growl to a
squeal when a target was detected.
The Surfmaster Dual Field is different. It is the
result of over fifteen years of research and develop-
ment. Our goal was to develop a Pulse Induction
metal detector which could match the sweep speed,
sensitivity, stability and ease of use of an Induc-
tion Balance VLF without responding to wet salt or
mineralized ground. The Surfmaster Dual Field may
be swept either quickly or slowly with virtually no
loss in sensitivity. It was designed to be more sensi-
tive to gold and copper-nickel alloys than to other
metals.