User's Manual

Innovator CU0TD-1/CU0RD-1 – CU4TD/CU4RD Board Descriptions
ATSC Transmitter/Regenerative Translator
Instruction Manual, Rev. 1 59
(A6) Amplifier Assembly (1309621) – Used in the CU0TD/RD-1
The (A6) Amplifier Assembly (1309621) is made up of (A6-A1) the 2 Stage UHF
Amplifier Board, 24V (1309608). The assembly has approximately 33 dB of gain.
(A6-A1) 2 Stage UHF Amplifier Board, 24V (1309608)
The 2 Stage UHF Amplifier Board, 24V (1309608) consists of a driver stage with a
gain of +14dB and two parallel connected final amplifier stages each with a gain
of +14dB. 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 Q2. 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 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 (1315008 used w/External Axciter Drawer or 1312566
used in all other applications) – Used in the CU0TD/RD-2 and CU0TD/RD-3
The (A6) Amplifier Assembly (1312566 or 1315008) is made up of (A6-A1) the 2 Stage
UHF Amplifier Board (1308784) and (A6-A2) the RF Module Pallet, Philips, High Output
(1309580). The ALC Board (1308570 is used in the 1312566 Assembly & the 1315006
is used in the 1315008 Assembly) is also part of 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