User's Manual

32 / 36
User Manual
Rev. 2.0 - 26/06/19
TEX702LCD
ELETTRONICA
7.3 Telemetry board
This board is designed to inform the user of the equipment operation state. All
input and output signals are available on the DB15 connector.
The same board also features the “INTERLOCK” BNC connector for disabling the
device. By grounding the central pin, the output power is reduced to zero until the
connection is removed.
When an R.V.R. amplifier is used, this connector is linked to the power amplifier
REMOTE or INTERLOCK by means of a BNC-BNC connection. In case of amplifier
faults, the central conductor is grounded thus forcing the machine to enter in
stand-by mode.
7.4 Power Supply
The TEX702LCD power supply unit is a switching-type unit whose +45 V main
stabilizers for generating continuous +5 V, +18 V and -18 V voltages for supplying
the other equipment circuits. Note that the power supply is a “direct from mains”
type, or rather it is without a transformer, and it can be connected to any voltage
between 90 and 260 V without any adjustments or manual settings.
7.5 Power Amplifier
The final power stage is enclosed in a totally shielded metal container fastened
in the centre of the device.
The RF signal coming from the “main” card reaches the pilot, is amplified and is
then sent to the final stage that sees to its final amplifications up to 700W.
The amplification stage consists of two main blocks.
In addition to the actual RF amplification, this circuit carries out the following
functions:
• Measures of the forward and reflected power by means of directional
couplers
• Low-pass filtering of the RF signal in output
On this card is an RF sample approximately -46dB compared with the output that is
available on a BNC connector underneath the output connector of the transmitter.
This sample is useful for checking the characteristics of the carrier, but not of the
higher order harmonics.