Specifications
B.5.1 Synthesizer Interface Switching
Normally, Synthesizer Interface A is selected for operation and
a relay on the RF Interface supplies Sythesizer Interface A with
+22VDC and +8VDC in addition to selecting the Sythesizer
Interface A RF output. Optional Synthesizer Interface B, if
installed, can be selected by switching the relay to the opposite
position.
B.5.2
Fault Sensing
Faultsensing for the activeSynthesizer Interface is accomplished
by applying the Synthesizer Detector Output to a comparator. If
the Synthesizer Interface output is not present, the comparator
sends a Synthesizer Fault to the Controller board.
The inactive Synthesizer Interface comparator is inhibited from
causing a Synthesizer Fault.
B.5.3
Power Supplies
+22VDC is regulated down to +15VDC and +5VDC to power
circuits on the board.
B.5.4
Combined Transmitter RF Switching
Several circuits on the board are reserved for combined transmit-
ter applications and are not used in a single system transmitter.
Refer to the combiner technical manual for information regard-
ing the use and function of these circuits.
B.6 Detailed Circuit Description
Refer to the schematic diagram for the RF Interface board (839-
7930-515) for all descriptions in this section.
NOTE - Any part of the schematic that is contained within dashed
lines is not being used in this application and therefore the parts
are not installed.
B.6.1
Power Supply Switching
RelayK1andSynthesizerSelectswitchS2areshowninthe
normal Synthesizer Interface A selected position. +22VDC and
+8VDC are connected to Synthesizer Interface A at J2 by K1
contacts 12 and 4 and K1 contacts 11 and 3 respectively.Indicator
DS3, Syntheiszer Interface A Selected, is connected to the
+22VDC supply and will be illuminated GREEN.
When K1 is energized, the supplies are connected to optional
Synthesizer Interface B at J9 and DS4, Synthesizer Interface B
Selected, will illuminate.
Crystal Heater Select jumpers P1 and P2 are normally jumpered
2-3, they are disconnected when an RF Interface board is used
with a Synthesizer that does not require crystal heaters.
B.6.2
RF Interface Output Switching
B.6.2.1 Synthesizer Interface A Selected
Transmitter Drive Out (from Synthesizer Interface board A)
enters at J3-1 and passes through the K1 contacts 2 and 10 to TP5
RF Out and J7-1. Transmitter RF Drive at J7-1 then connects to
the Driver Combiner Motherboard and eventually to the Buffer
Amplifier.
B.6.2.2 Synthesizer Interface B Selected
If selected, Transmitter Drive Out (from Synthesizer Interface
B), enters at J8-1 and passes through the K1 contacts 6 and 9 to
TP5 and J7-1.
B.6.2.3 Relay Supply
Zener diodes CR1 and CR6 are connected to the +22VDC, and
are in series with the relay coil. This drops the +22VDC to
+12VDC for the relay coil at pin 13. If the Synthesizer Select
switch, S1, is in the B position, a ground is applied to the relay
coil at pin 14 and the relay energizes. Likewise, a remote/ex-
tended control input will deliver Remote RF Select-H logic high
to J11-7 that turns Q1 fully on and also applies a ground to K1.
B.6.3
Fault Sensing Comparators
B.6.3.1 Synthesizer Interface A
Normally, when Synthesizer Interface A is selected, the RF(-)
input at J12-3 is -.6VDC and RF(+) input at J12-1 is +3.5VDC,
and comparator U2-2 output at TP11 is a logic high.
Should Synthesizer Interface A fail, the RF(-) voltage will be
greater than the RF(+) voltage and TP11 will go to a logic low.
The voltage at U2-9 will be 2.6VDC, established by a resistor
divider, R8 and R10.
B.6.3.2 Synthesizer Interface B
When Synthesizer Interface B is selected, the same voltages are
supplied to J10-3 and J10-1, and the output of U2-1 at TP12 is a
logic high. If a failure occurs, the voltage at U2-11 will be
2.6VDC.
B.6.4
Fault Sensing Selection
B.6.4.1 Synthesizer Interface A Selected
K1 is de-energized and approximately +10VDC is supplied to
U2-8 through the relay coil. Normally U2-9 is +15VDC and the
output of U2-14 at TP6 Synthesizer Fault is logic high.
TP5
B-2 888-2339-002
Warning: Disconnect primary power prior to servicing.