MXD5U OPERATIONS AND MAINTENANCE
2.4
2.4.1
E
XTERNAL
R
EMOTE
C
ONTROL
C
ONNECTIONS
External remote controls are intended to interfacing to a third party remote control vendor such as Moseley or
Gentner if such systems are installed or available at the transmitter site. These external controls function in
parallel with the serial remote commands implemented with the Larcan supplied remote control program.
These remote signals are available on the 15-pin D-connector labeled Telemetry on the rear panel of the MXD5U
transmitter. The remote controls can be broken down into four categories, control inputs, status outputs,
telemetry outputs and interlock as follows:
Remote Command Inputs
There are only three remote commands available to the operator, these being TX ON, TX OFF and VSWR Reset.
In the table of remote signals, all remote commands have an RC_prefix.
All remote controls are active low, opto-isolated inputs configured as shown at left, all of which require a GROUND
for assertion and the activator to be able to sink 15mA or more for at least 200ms to accomplish reliable keying.
Each of these is current-limited by an individual resistor. A ground reference pin is provided at pin 12 to ease the
interface task since all these remote commands are active low and require a short to ground.
Figure 4 Remote Command Inputs
2.4.2 Remote Telemetry Outputs
There are only four remote telemetries available to the operator, these being RF forward power, RF reflected power,
AGC voltage and Cutback voltage. In the table of remote signals, all remote commands have a RT_ prefix.
The only further note on the telemetry outputs concern the AGC and Cutback telemetry levels. These levels are
normally sent to the PreAmp attenuator and range from 0V to about 10V. The circuit that generates these
telemetries for the remote interface only has a range of 0V to 5V and so the values of these two telemetries are
actually half of their true value. That is an AGC telemetry reading of 2.3V actually represents an AGC voltage
level to the PreAmp attenuator of 4.6V.
All telemetry outputs of the transmitter are designed to operate between zero and +5V, referenced to ground.
Where possible and practical, factory calibration is standardised on 100% normal power or 100% normal voltage as
applicable, and adjusted to d4V to the appropriate telemetry output. All come from op-amps that can supply
only a few mA. A ground reference pin is provided at pin 12 to ease the interface task since all these remote
commands are active low and require a short to ground.
Figure 5 Remote Telemetry Outputs
PUB09-03 Rev 0 April 16, 2009
09-03-6
MXD5U Operations and Maintenance
