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3-2. USER SYSTEMS OPERATION
When used in another system, the ACOM2000SW remote antenna switch
must be powered with +27VDC (150mA) and can be controlled via the 4 -
bit BCD code. This code could be generated from any automatic antenna
system or manually via a simple coding manual switch plus 4 resistors
1.2kOhm/1W. Connect them similarly to the RDY output (see fig.4 - 1).
Antenna switching will follow the input BCD code number passed to the
control input. The RDY output signal will stay in logical high state always
when an antenna is switched on and is ready to transmit. You could use this
signal to improve switching reliability or just monitor it via a LED for feed-
back information.
If a new antenna number is requested changing the input BCD code, first
the RDY output falls to the logical low state and the incoming RF power is
checked. If its level is greater than 10-12W, the switching will be suspended
until RF disappears. When switching is safe, the request will be executed
and the RDY signal returns in logical high for only 0.15 seconds.
We recommend that some inexpensive lowpass filters be added to all con-
trol cable wires in your control box. Look into the schematic diagram of the
antenna switch just to get an idea (Fig.4 - 1). Filters with cut - off frequency
substantially below the lowest operating frequency (for instance 50 - 100kHz)
will substantially improve the EMC performance of your control unit.
4. MAINTENANCE
4-1. The ACOM2000SW Schematic Diagram
See Fig.4-1. The remote antenna switch ACOM2000SW has two main parts:
a control circuit and the proper switch.
a) The control circuit decodes the input 4 - bit BCD antenna number to 1
out of 10 output relay driving signals. Meanwhile it continuously monitors
the incoming RF power in order not to allow hot contact switching if
accidentally antenna number is changed during a transmission. Four func-
tional blocks serve this: I/O interface, antenna changes founding register,
