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PT-8000A Operating Manual v2.00.33
If a large resistance will complicate the unfolding, please spread the bail easy for hurdle the
locking nib to avoid damage of the equipment foot.
3.4
Antenna Considerations / Antenna Tuner
Standing wave ratio (SWR) may increase significantly when using an antenna outside of the specific
frequency range for which it is tuned. The final power amplifier will operate at peak performance only
when its load is resistive – i.e. the SWR is close to 1.0.
Therefore the PT-8000A is equipped with an automatic antenna tuner (ATU) which does not actually tune
the antenna. The ATU instead matches the feed line to the final amplifiers so they always "see" a SWR
close to 1.0. The ATU has its limits – tuning mismatches with SWR greater than 2.0 become difficult and
will exceed the capabilities of the ATU. Using a tuned or resonant antenna with 50 Ohm impedance at the
feed point for the specific frequencies is highly recommended. The purpose of the ATU is to ensure that a
resonant antenna can be used at the limits of the band selected with optimum performance of both PT-
8000A and antenna system.
Never try to hook up a symmetrical open feeder line (balanced, twin-lead, ladder line etc.) directly to the
PT-8000A. Instead use 50 ohm coaxial feeders only. The connectors supplied on the PT-8000A are all
Type N.
With the ATU it is acceptable to use a broadband antenna system like a log periodic or T2FD system which
trade wide bandwidth for an SWR ranging as high as 2.0.
3
Fig. 1
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