CIRCUIT DESCRIPTION
6-14
September 1994
Part No. 001-2008-300
Pin 12
SYN CS EX
Exciter main synthesizer chip select. It allows
data input to the specific synthesizer chip when the
line is pulled to a logic low.
Pin 13
TX MOD
The audio from the TPI card in the Controller
processes a number of inputs to the Universal Station
per the TIA specifications to produce the signal on
this pin. This signal goes through the RFIB and then
to the Exciter. A 707 mV RMS (2V P-P) sine wave at
1 kHz provides 60% of system deviation in the trans-
mitter. The DC voltage on the line is 3.5V
±
0.1V.
The source impedance should be low (output of an op-
amp or analog switch < 200 ohms) and the input
impedance will not be less than 10k ohms.
Pins 14-15
GROUND
Carries ground current between the RFIB and the
Exciter board.
Pin 16
SYN LK EX
Exciter main synthesizer lock detector output.
The synthesizer is locked with a TTL logic high state.
Pins 17-18
HS LK EX-HS CS EX
Not used at this time.
Pin 19
RF CLK
The clock controls the Exciter synthesizer when
loading. The input source in the Controller is TTL
with the speed determined by the synthesizer chip.
There could be as many as four synthesizers and a
shift register.
Pin 20
RF DATA
A data pin from the Controller which has the dual
role of loading the synthesizer chip and adjusting the
power control D/A lines for proper output power. The
data has TTL levels. Up to four synthesizer chips and
a shift register could be connected to this pin.
6.4.6 RECEIVER CONNECTOR (J103)
The connector from the Receiver (J201) to the
RF Interface board (J103) links the Receiver to the
TPI card in the Controller Backplane.
Pin 1
VCC1
+15V with a nominal current of 1A provides cur-
rent from the RFIB to the Exciter, Receiver.
Pin 2
-
6 UNUSED
Pin 7
RSSI
This pin is the Receive Signal Strength Indicator
(RSSI) to the Controller. The RSSI is used to tune the
Receiver front-end during test mode. The dynamic
range is 40-60 dB. Output from an op-amp with the
voltage going from 0.5V to 4.5V. The level has an
adjustment in the Receiver.
Pin 8
UNUSED
Pin 9
RX WBAND
The receive wide band audio is from the demodu-
lator and goes to the TPI card in the Controller card
cage. Typical amplitude is 387 mV RMS (-6 dBm)
and 2V DC with Standard TIA Test Modulation into
the Receiver. The only wave shaping in the Receiver
board is a 31 kHz RC LPF which strips off the 450
kHz IF. Buffering is done with an op-amp which can
drive a 10k ohm load.
Pin 10
UNUSED
Pin 11
GROUND
Carries ground current between the RFIB and the
Receiver board.
Pin 12
SYN CS RX
Receiver main synthesizer chip select. This chip
is the same part as used in the Exciter. A low enables
loading the Synthesizer.
