Specifications

Section T
3F Controller Board
T.1 Introduction
This section describes the 3 Frequency Controller Board. Topics
include Function, Location, and troubleshooting.
Board # 843 5400 733
Schematic # 843 5515 842
PWA # 992 9511 588
T.2 Function
The 3F Control Board is used to send 1 of 3 frequencies to the
synthesizer module. Depending on the 3 inputs lines that come
from the 3F select board will determine the Frequency.
When a Frequency is selected on the 3F Select board the 3F
Controller will issue a frequency change command to the freq
control board. The transmitter will shut off and the transmitter
will change to the frequency selected.
The frequency change will be removed once both servos have
reached the reference within 0.060 Volts or the NORM/CALI-
BRATE switch (S100) is in the CALIBRATE position.
NOTE:
When S100 (NORM/CALIBRATE) is in the CALIBRATE position
neither the FREQUENCY CHANGE or the NORMAL LED on the
front panel will be illuminated.
The 3F controller will issue an F1, F2 or F3 command to the freq
Controller this will determine the Ant and Net VSWR settings
The 3F controller will issue the correct binary value for the freq
selected to freq controller, which will decode that value and
select the appropriate settings throughout the transmitter.
T.3 SERVO CONTROL
The servos will travel to a predetermined position control by the
variable potentiometer. See chart below.
Freq U31 pin Tune REF U31 pin Load REF
1 6 R44 & R57 10 R26 & R50
2 7 R48 & R52 11 R46 & R55
3 8 R27 & R56 12 R25 & R54
U31 pin Tune POS U31 pin Load POS
5 R47 & R51 13 R45 & R49
Depending on the distance the servo has to travelin order to reach
its reference will determine the speed of the servo.
If the Difference between the Tune Ref Voltage and Tune Pos
Voltage is greater than 2.45V than the 3F controller will Active
the Tune Raise/Lower.
If the Difference between the Tune Ref Voltage and Tune Pos
Voltage is less than 2.45V and greater than 1.22 volts than the 3F
controller will pulse the Tune Raise/Lower .every 0.125 seconds.
If the Difference between the Tune Ref Voltage and Tune Pos
Voltage is less than 1.22V and greater than 0.060 volts than the
3F controller will pulse the TuneRaise/Lower.every0.5 seconds.
If the Tune Ref Pos is Greater than the Tune Ref Voltage then the
Tune Lower will be activated.
IftheTuneRefPosislessthantheTuneRefVoltagethenthe
TuneRaisewillbeactivated.
The Tune Raise/Lower command stops once the Difference
between the Tune Ref Voltage and Tune Pos Voltage is less than
0.060 volts
Once the servos have reached that position the 3F controller will
issue a Normal command to the Freq Controller.
You are then able to select Low, Med, or High power level.
NOTE:
If the servos do not reach the position required then the 3F Con-
troller will not issue a Normal Command. An RF Mute will be
generated until the difference between the Ref & Pos voltages is
less than 0.3 Volts.
T.4 Location
The 3F Controller board is located on the Left PAC front Door.
Above the Frequency Control Board. See View 24
2/12/04 888-2339-002 T-1
WARNING: Disconnect primary power prior to servicing.