Electronika LDMOS UHF SERIES, User Manual, Page: 33 / 52

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Figure 2: Usage of the digital input signals of the telemeasures connector
AGC / EXCITER
The connector called J10, as the telemeasures connector and the RS485 bus, is wired to a DB9 female
connector placed on the rear panel of the amplifier. This connector allow the implementation of an automatic
gain control between an exciter and the amplifier. A voltage signal related to the forward output power
supplied by the amplifier is provided through two pins of the AGC connector. Connecting one of these to the
relevant input pin of the exciter, this can pursuit a given voltage level, so that the output power is always
constant. In order to avoid that, in case of an alarm decreasing the forward power, the exciter increases its
output level due to the AGC, thus damaging the amplification stages, the connector is provided with two
digital output lines called AGC Alarm. Under alarm conditions, this lines are brought by the micro-controller
at a low level, so that the exciter can stop the AGC.
Table 4 shows the connection between the J10 connector on the board and the DB9 connector on the rear
panel, along with the description of each pin (the direction of the pin is referred to the position of the micro-
controller on the board).
level of the interlock signal becomes high (this line has a pull-up towards the +5V power supply voltage as
well) and the interlock protection activates switching off the amplifier. Note that in case the interlock protection
is not used, the pin 4 of the DB9 telemeasure connector and the earth pin (pin 5) must be short circuited.
Otherwise it is possible to disable the monitoring of the interlock chain from menu (see user manual).
Figure 2 shows a typical usage for the digital input signals to turn on and off the amplifier and for the interlock
alarm.