User's Manual

Innovator CU0TD-1/CU0RD-1 – CU4TD/CU4RD Board Descriptions

ATSC Transmitter/Regenerative Translator

Instruction Manual, Rev. 1 60

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, Philips, High Output (1309580)

The RF Module Pallet, Philips, High Output, (1309580) is made from the RF

Module Pallet, High Output w/o Transistors (1309579). 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 amplification circuit consists of push-pull amplifier blocks V1 and V2,

connected in parallel, operating in class AB. In order to match the impedance of

the transistors to the characteristic impedance of the input and output sides,

matching networks are placed ahead and behind the amplifier blocks.

Transformers Z3 and Z4 at the input to V1 and V2 and Z5 and Z6 at the output

of V1 and V2 serve to balance the input and output signals. The paralleling

circuit is achieved using the 3-dB input coupler Z1 and the second part of Z1,

which is the 3-dB output coupler. The working point settings of the amplifier

circuits are factory implemented by means of the potentiometers R11 and R12

and should not be altered. The combined output of Z1 connects to the RF output

jack of the board at J2. The output of the amplifier assembly at J2 connects to J1

on (A7) the output detector board.

(A6) Amplifier Assembly w/878 devices (1312191) – Used in the CU0TD/RD-4

& CU0TD/RD-5

The (A6) Amplifier Assembly (1312191) is made up of (A6-A1) the 1 Watt Amplifier

Board (1310282), (A6-A2) the BL871 Single Stage Amplifier Board (1311041), and (A6-

A3) the Dual 878 Pallet Assembly (1313170 or 1310138). The ALC Board (1308570) is

also used with this assembly. The entire amplifier assembly has approximately 36 dB of

gain.

(A6-A1) 1 Watt UHF Amplifier Module (1310282)

This board is a broadband UHF amplifier capable of producing an output power in

excess of 1W Peak. It is normally operated at an average power of 100 mW 8VSB

or lower. It consists of two AH202 MMICs operating in parallel. The board is

approximately 16 dB.

(A6-A2) BL871 Single Stage Amplifier Board (1311041)

This board consists of a single stage amplifier operating at +42 VDC. The board

has an overall gain of about 16 dB. The input to the board passes through a 3 dB

attenuator consisting of R11-R13, and then is applied to the gain stage, which

consists of a single LDMOS transistor Q1 operating in Class AB. The bias voltage

for the transistor is generated through the voltage regulator U1, and is adjusted