User's Manual | ACOM 500S | 160-4
m Linear Power Amplifier
March 2023
S e c t i o n INSTALLATION | Page 21 of 66
The switching voltage presented from amplifier
KEY IN
connector to the transceiver
"ground on transmit" output does not exceed 12 V (positive to the ground). The closed-
circuit current is below 6 mA (see Section
8.2.a) Receive / transmit control
Your amplifier will not work if
KEY IN
input is not connected properly.
Transceiver producers give different names to this output and they are for instance
TX-GND, SEND, T/R-LINE, PTT, etc. Some transceivers require that "ground on transmit" is
implemented via a software command, or by changing the setting of a switch on the rear
panel, or interior of the transceiver. Check your transceiver's manual.
c)
KEY OUT
connector
This is the amplifier's transmit-enabling control output from amplifier to the transceiver.
The
KEY OUT
connector provides an extra control signal from the amplifier to the transceiver. It can be used
for improving the receive/transmit (RX/TX) switching safety.
NOTICE
KEY OUT
is a low-power open-drain output, make sure that the signal voltage coming from
the respective transceiver connection does not exceed 50 VDC (open circuit) and the
closed-circuit current is below 20 mA.
If your transceiver has a suitable input that disables transmission unless grounded externally, we recommend
that you connect it with a shielded cable terminated in a Phono (RCA) connector to the
KEY OUT
connector
(see
Figure 2-3 | Rear panel - Connections
, Pos. (c)) of the amplifier.
ACOM 500S will operate normally with
KEY OUT
unconnected if your transceiver has no
such input.
Transceiver producers give different names to this input and they are for instance
TX-INHIBIT, MUTE, LINEAR, etc. Check your transceiver's manual.
d)
RF INPUT
connector
Connect a suitable coaxial cable from the transceiver output to the amplifier
RF INPUT
SO-239 connector
(see
Figure 2-3 | Rear panel - Connections
, Pos. (d)), using PL-259 plug.
NOTICE
In order to avoid a damage, turn off your transceiver's internal antenna tuner.
