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At a function selection all relays are switched off, thus the effect of the inductors and the capacitors on the remote-
unit impedance transformation is eliminated. While the BYPASS function is active, the AUTO TUNE function is not
accessible (the button is dark).
This way, you can operate without re-tuning the AATU provided the antenna SWR is acceptable in a certain
frequency range.
Using a coaxial feeder at SWR above 3:1 is not recommended in the HF range.
When the SWR is higher than 3:1 and you want to use this antenna at high RF
power, you risk damaging the coaxial cable between the station and the antenna.
The cause is increased current and voltage along the cable, as well as a large
amount of heat they generate in the cable wires and insulation. We recommend you
use AUTO TUNE in either OPERATE, STATUS, or SWR-CHK function in such
conditions in order to use your cable safely as well as to increase the radiated
power.
Besides operating, you may use this mode also for preventive checks of your antenna and feeder system. While in
BYPASS, check the antenna SWR for several representative frequencies and compare with data copied providently
while you have been confident the system was intact.
The function can be restarted via the button Enter. To exit, press the button Esc until the main menu appears.
4-4. Function STATUS
When you select the function STATUS between the square brackets in the main menu and then press Enter, you will
see the function inscription:
Various figures may appear in the example above. On the upper LCD line is shown the current position of the main
RF-tuning blocks. They are configured in a standard low-pass Pi-circuit to perform the impedance matching in the
remote unit. See fig.5-1 and S.5-3 for details. The following symbols are used:
CT – comprises a group of 8 capacitors connected in parallel to the transmitter input;
L – comprises a group of nine inductors connected in series between the transmitter input and the antenna output;
CA – comprises a group of six capacitors connected in parallel to the antenna output;
CS – a capacitor connected in series to the antenna.
To the right of each group symbol is shown a figure in hexadecimal code. Should one convert it in binary code, the
figure would point to the elements in a group used (1) and not used (0) for the current tuning. For CS are used only Y
(used) or N (not used). These figures are useful for preventive checks and troubleshooting of the AATU that can be
accomplished by trained personnel.
On the bottom line, below each group symbol is shown the used percentage of the usable reactance (at that
frequency) to achieve the current tuning. In other words, this is the used resource of the AATU matching circuit. It
could give you a hint about at least two issues:
what the margin is to keep achieving antenna match at antenna-impedance variations in the future (due to
-
exterior influence - weather or antenna surroundings change, new or moved antennas or any massive objects
etc);
you may provisionally copy data about the resource used by the AATU in the frequency range and antennas or
-
your interest. Eventual changes in the future would forewarn you when you may need any antenna- or feeder
changes or repair in order to increase the margin, thus preventing possible problems.
You can start the AUTO TUNE procedure while using STATUS function and return
back to the STATUS by pressing the button Enter.
The function can be restarted via the button Enter. To exit, press the button Esc until the main menu appears.
BROAD BAND
C A U T I O N
CT=3E L=012 CA=00 CS
24%
3%
0%
N O T E
N
16
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