Acom 700S, Operating Manual, Page: 18 / 30

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C A U T I O N
In order to provide time for the relays to switch safely from receive
to transmit, the transceiver should provide a dead time i.e. must
“notify” the amplifier in due time by grounding the control KEY
IN input not later than 10ms before feeding drive power toward
the amplifier RF input. Otherwise, the protection system will read
“HOT SWITCHING ATTEMPT” and will trip off.
In Operate mode the KEY OUT output (S. 2-3(c)) follows the state of the KEY-IN input only after all
conditions for safe transmission have been found good by the amplifier control unit. The KEY OUT
output duly disables transmission, if the amplifier is not ready.
The two modes - Operate and Stand-by - may alternatively be changed:
- either manually (locally) – by pressing the OPR/STB button – see the basic screen in Fig. 3-2,
or automatically – when if the AUTO OPERATE option is activated – see S. 5-4(c).
N O T E
Access to the Operate mode can be locked in the AMP SERVICE
menu, the OPERATE ACCESS option (S. 5-2 and Fig. 5-2).
c) AUTO OPERATE option can be turned on/off by the operator in the USER PREFERENCES
menu – S. 5-4 and Fig. 5-4 - or by a remote control command.
When the AUTO OPERATE option is OFF, the two modes Operate and Stand-by can be changed
alternatively by the OPR/STB button or by a remote control command. At a SOFT FAULT protection trip,
the amplifier will revert to Stand-by and wait for the operator to return it to Operate by pressing the OPR/
STB button.
When AUTO OPERATE is ON (S. 5-4), the amplifier will start up in Operate mode. At a SOFT FAULT
protection trip, the amplifier will first revert to Stand-by, but will return automatically to Operate mode in
about 4 seconds.
Even at AUTO OPERATE on, the operator can revert to and remain in a Stand-by mode manually
by the OPR/STB button or by a remote command. The next OPR/STB button push will switch the
amplifier to the Operate mode and restore the normal operation of the AUTO OPERATE option.
4-2. Band change, standard and expanded frequency coverage
When connected to a transceiver with CAT, the amplifier will change frequency bands automatically,
following the transceiver’s operating frequency changes.
Without CAT connection, the bands can be changed either manually or automatically (by the built-in
frequency counter).
The bands are changed manually by the up and down BAND buttons.
For an automatic band change via the built-in frequency counter, make a quite short pre-transmission
(100ms is enough) – a CW dit, or a sound on SSB) and release a PTT for a moment before the main
transmission.
If the new frequency is out of the amplifier’s frequency range (S. 8-1(a)), the transmission request will
be denied and the following fault message will appear on the screen:
“FREQUENCY OUT OF RANGE”
The amplifier specifications are guaranteed within the bands listed in S. 8-1(a)). Frequency coverage
changes could be negotiated with the manufacturer.