Specifications
If a frequency of 936 kHz was entered on the front panel, the
transmitter will be in Band 40, and the 6 Bit outputs from the
BAND ENC PAL will be as seen below.
BCD INPUT 6 BIT OUTPUT BAND 0
MSD1 1
MSD2 0
MSD4 0
MSD8 0 Bit 5 1 MSB
2MSD1 0 Bit 4 0
2MSD2 1 Bit 3 1
2MSD4 1 Bit 2 0
2MSD8 0 Bit 1 0
3MSD1 0 Bit 0 0 LSB
3MSD2 0
3MSD4 0
3MSD8 0
If a frequency of 585 kHz was entered on the front panel, the
transmitter will be in Band 60, and all 6 Bit outputs from the
BAND ENC PAL will be logic high.
BCD INPUT 6 BIT OUTPUT BAND 0
MSD1 0
MSD2 0
MSD4 0
MSD8 0 Bit 5 1 MSB
2MSD1 1 Bit 4 1
2MSD2 0 Bit 3 1
2MSD4 1 Bit 2 1
2MSD8 0 Bit 1 0
3MSD1 0 Bit 0 0 LSB
3MSD2 0
3MSD4 0
3MSD8 1
NOTE
Refer to the Transmitter Band Chart, for the following example.
If operating at a Transmitter Frequency of 684 kHz, the chart
shows that the Frequency Band is 54. By converting this decimal
number back to its binary equivalent, the logic levels of the
BAND ENC PAL outputs may be determined.
OUTPUT LOGIC LEVEL DECIMAL EQUIVALENT
Bit 5 1 32 32
Bit 4 1 16 16
Bit 3 0 8
Bit 2 1 4 4
Bit 1 1 2 2
Bit 0 0 1 __
54
This Band Select Data is connected to the Frequency Control
Interfaceboard at J1, and is used to encode into the proper outputs
for each bandswitched component.
Q.5.8
TUNE And LOAD Multimeters
The Frequency Control board has two identical Multimeters used
for indicating the loading and tuning servo parameters simulta-
neously for use in the tuning process. The two parameters meas-
ured are the servo reference voltage used for presetting the servo
during the Frequency Change mode and the servo feedback
voltage used to monitor the actual location of the servo during
the fine tuning adjustments. The TUNE Multimeter may also be
used as a Multimeter is measure other voltages.
Q.5.9
Multimeters
Multimeters U9 and U10, are 3 1/2 digit multimeters with LED
readouts. In this application, the meter is fixed reading of 2 digits
in the mantissa and 1 digit for decimal indication. A display of
the polarity is automatically provided.
Q.5.9.1 Supply Voltages
Each Multimeter requires +5VDC and -5VDC power supplies,
and a +2.00VDC reference voltage. These references are devel-
oped by adjustable voltage dividers R27 and R36 which may be
measured at TP1 and TP2.
Q.5.9.2 Multimeter Inputs
The input to U9 is connected to K1-8 and the input to U10 is
connected to U8-4, both part of the Multimeter Autoswitch. The
actual DC voltage at either of these two inputs, will be the voltage
that the Multimeter will display when activated.
Q.5.9.3 Lamp Test
TheLampTestFunctionisusedtoveritythatallLEDdisplays
are functional. When JP1 is jumpered 2-3, both Multimeters
should display -88.8.
Q.5.9.4 LED +5VA Voltage
The LED displays only become activated when the Servo Fault
Enable from the STATUS PAL goes logic low. The +5VA supply
is activated by the LED Display Switch, the Multimeters are
illuminated and may be used.
Q.5.10
Multimeter Autoswitch
It is necessary to monitor the servo reference voltage during the
Frequency Change mode in order to preset the reference voltage.
It is necessary to monitor the servo feedback voltage during fine
tuning. The purpose of this circuit is therefore to switch the
desired sample depending upon the mode selected.
Q.5.10.1 Meter Sample Inputs
The servo voltage meter samples enter on J1 and are connected
to analog switch U8. The Multimeter samples enter on J2 and are
connected to S7.
Q.5.10.2 Analog Switch
AnalogswitchU8isshownwithS3intheServoMeterNormal
position and in either the Low or High Power Tune mode. The B
and C inputs at U8-10 and U8-9 will be logic low, and the
switches are in the position drawn.
The TUNE Position meter sample passes from U8-2 to U8-15
and then through K1-2 to K1-8 and is connected to the input of
the TUNE Multimeter.
The LOAD Position meter sample passes from U8-5 to U8-4 and
is then connected to the input of the LOAD Multimeter.
When in the Frequency Change mode or if the Servo Meter
Reference is selected by S3, the B and C inputs are a logic high,
and each Multimeter input is switched to the Reference meter
sample.
Q-4 888-2339-002
WARNING: Disconnect primary power prior to servicing.