User's Manual

Innovator CU5-1800BTD/BRD ATSC Transmitter/ Board Descriptions
Regenerative Translator
Instruction Manual, Rev. 0 51
connected to the final amps. The final amplification circuit consists of parallel-connected
push-pull LDMOS amplifier circuits Q1 and Q3 operating in class AB each with
approximately 14 dB of gain. The board uses a power supply voltage of 24V. The RF
transistors are operated at a voltage of 24V generated by the voltage regulators U6 and
U7 for Q2, U5 and U3 for Q3 and U1 and U3 for Q1, which provide a separate regulated
voltage to each transistor. In order to match the LDMOS impedance to the
characteristic impedance of the input and output sides, matching networks are located
before and after the amplifier circuits. The hybrid coupler U2 splits the input to the
parallel amplifiers and the hybrid coupler U4 combines the amplified outputs. The
combined output connects through a directional coupler to J1, the RF output jack of the
board. The directional coupler provides an RF sample at J3 that is used by an external
overdrive protection circuit located on (A5) the ALC Board. The RF output of the board
is 6W maximum 8-VSB. At this power level the board draws approximately 3.6A total
from the power supply.
(A6) Amplifier Assembly (1312566) – Used in the CU30 and CU50
The (A6) Amplifier Assembly (1312566) is made up of (A6-A1) the 2 Stage UHF
Amplifier Board (1308784) and (A6-A2) the RF Module Pallet w/Philips transistors
(1300116). The ALC Board (1308570) is also used with this assembly. The assembly
has approximately 36 dB of gain.
(A6-A1) 2 Stage UHF Amplifier Board (1308784)
The 2 Stage UHF Amplifier Board, (1308784) consists of a driver stage and a parallel
connected final amplifier stage which have a total gain of approximately 23 dB. The
working point settings for the 2 Stage Amplifier Board are factory set using the
potentiometers R32 for Q2, R15 for Q1, and R24 for Q3 and should not be altered. The
input RF connects to the first amplifier stage U2, which has a gain of approximately 14
dB. The output is split by U2 and connected to the final amps. The final amplification
circuit consists of parallel-connected push-pull LDMOS amplifier circuits Q1 and Q3
operating in class AB each with approximately 14 dB of gain. The board uses a power
supply voltage of 28-32V. The RF transistors are operated at a voltage of 24V
generated by the voltage regulators U1 for Q1, U5 for Q3 and U6 for Q2, which provide
a separate regulated voltage to each transistor. In order to match the LDMOS
impedance to the characteristic impedance of the input and output sides, matching
networks are located before and after the amplifier circuits. The hybrid coupler U2 splits
the input to the parallel amplifiers and the hybrid coupler U4 combines the amplified
outputs. The combined output connects through a directional coupler to J1, the RF
output jack of the board. The directional coupler provides an RF sample at J3 that is
used by an external overdrive protection circuit located on (A5) the ALC Board. The RF
output of the board is being used as a driver and has a level of 3W maximum 8-VSB. At
this power level the board draws approximately 1.8A total from the power supply.
(A6-A2) RF Module Pallet w/Philips Transistors (1300116)
The RF Module Pallet, w/Philips Transistors, is made from the RF Module Pallet w/o
Transistors (1152336). This broadband amplifier is for the frequency range of 470 to
860 MHz. The amplifier is capable of delivering a maximum output power of 100 Watts
peak, with an amplification factor of approximately 13 dB.
The RF Module Pallet w/Philips Transistors (1300116) is a broadband amplifier for the
frequency range of 470 to 860 MHz. The amplifier is capable of delivering a maximum