Specifications

(depending upon the Modulated B- Voltage) and the RF Amp is
turned ON.
Connectors J1, J2, J3, and J4 carry the signal to the Big Step
Combiner Motherboards where it is distributed to each RF Amp.
L.4.2.6 FLEXPatch™ - Programmable RF Amp Selector
A Programmable RF Amplifier is assigned to each Mod Encoder,
therefore there are a total of five available in the transmitter.
ThisProgrammable RF Amp is alwaysat the bottom ofthelowest
Combiner Motherboard and therefore it’s turn-on/turn-off con-
trol line is the very bottom gold jumper plug on the associated
Mod Encoder.
Normally the Program Selector switches on each Mod Encoder
designate the steps as RF Amps RF152 through RF156, the
highest possible steps in the transmitter.
If an RF Amp should fail, one of these Programmable RF Amps
can be substituted it its place. Only a slight reduction in positive
peak modulation capability will result.
L.4.2.6.1 Digital Comparator
U4 is a Digital Comparator that controls the Programmable RF
Amplifier.
Program Selector Switches S7 LSB and S8 MSB are used to
provide an eight bit digital word to the Q comparator inputs Q0
through Q7.
The eight bit digital audio input (B1-B8) from U16 is applied to
the P comparator inputs P0 through P7.
When the incoming eight bit digital word value from U16 is
lower than the programmed eight bit digital word value, both
U4-1 and U4-19 are high and the Programmable RF Amp is
turned OFF.
Figure L-3. Cable Interlock and Fuse Fault
Detection Circuits
888-2339-002 L-5
WARNING: Disconnect primary power prior to servicing.