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Icom Interfacing
When interfacing the Z-100Plus with AH-3 and AH-4 compatible Icom radios (IC-706, IC-
7000, for example), the Z-100Plus may be operated from the radio’s
TUNER/CALL
button. Push
the
TUNER/CALL
button momentarily to toggle the bypass of the Z-100Plus. Push and hold the
TUNER/CALL
button for 2 seconds to initiate a memory tuning cycle. Note that the
TUNER
button on the Icom IC-756 Pro series transceivers will not activate the Z-100Plus, but pushing
TUNE
on the Z-100Plus will still automatically activate the carrier on the IC-756 Pro when using
the Icom interface cable. When using the IC-718, choose AH-4 from the tuner menu.
Yaesu Interfacing
When interfacing the Z-100Plus with an FT-857 or FT-897 using the optional Y-ACC cable,
the
Tune
button on the Z-100Plus is used to initiate a tune. The Z-100Plus will automatically key
the radio at the current power level during a tuning cycle and un-key when the tuning cycle is
complete.
THEORY OF OPERATION
Some basic ideas about impedance
The theory underlying antennas and transmission lines is fairly complex, and in fact employs a
mathematical notation called “complex numbers” that have “real” and “imaginary” parts. It is
beyond the scope of this manual to present a tutorial on this subject
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, but a little background will
help in understanding what the Z-100Plus is doing, and how it does it.
In simple DC circuits, the wire resists current flow, converting some of it into heat. The
relationship between voltage, current, and resistance is described by the elegant and well-known
“Ohm’s Law”, named for Georg Simon Ohm of Germany, who first discovered the principle in
1826. In RF circuits, an analogous but more complicated relationship exists.
RF circuits also resist the flow of electricity. However, the presence of capacitive and inductive
elements causes the voltage to lead or lag the current, respectively. In RF circuits, this resistance to
the flow of electricity is called “impedance”, and can include all three elements: resistive,
capacitive, and inductive.
The output circuit of a transmitter consists of inductors and capacitors, usually in a
series/parallel configuration called a “pi network”. The transmission line can be thought of as a
long string of capacitors and inductors in series/parallel, and the antenna is a kind of resonant
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For a very complete treatment of this subject, see any edition of the ARRL Handbook for Radio Communications (previously the
Handbook for Radio Amateurs).
