User Manual

Technical Description
Version 4 4-8 04/02/04
Amplifier (before Mixer)
The amplifier is used to amplify the RF signal before it is mixed with
the signal from the channel PLL. It also provides isolation for the
previous blocks.
Mixer
In the mixer, the carrier (139.3 – 163.3 MHz) from the channel PLL
and the decoupled RF signal (150 – 174 MHz) are mixed. In this
way an intermediate frequency (IF) of 10.7 MHz ± deviation is
obtained.
Amplifier (following Mixer)
The amplifiers, following the mixer, are used to amplify the signal
from the mixer.
4.4 FRONT PANEL DISPLAY BOARD
The Front Panel display board for the Extend-A-Page transmitter contains
display LEDs to indicate Extend-A-Page mode of operation. Descriptions of the
LEDs are given in the Appendix Page A-50. Signals to this board are brought in
via a 26 pin ribbon cable connectors from the Backplane (Connector P3).
Signals are buffered by an inverter to drive LEDs.
4.5 POWER SUPPLY
The power supply for the Extend-A-Page transmitter is, a switching power
supply, provides +12, -12 and +5 VDC voltages from 110 VAC input. The power
supply also accepts 220 VAC for international application. The power supply has
built –in short circuit protection with auto-restart and over voltage protection on 5
VDC.