User's Manual

Innovator CU0TD-1/CU0RD-1 – CU4TD/CU4RD ATSC Board Descriptions
Transmitter/Regenerative Translator
Instruction Manual, Rev. 2 114
The board has a gain of approximately 17 dB, and can operate at an output power of
150 Watts average power DVB, 220 Watts average power ATSC, or 440 Watts Peak Sync
plus sound in analog operation. The transistors are operated in quadrature, with one
transistor operating 90 degrees out of phase of the other, which provides for a very
good return loss across the UHF band on both the input and output of the board.
(A6) Amplifier Assembly 1316035– Used in CU0TD/RD-4 & CU0TD/RD-5
The (A6) Amplifier Assembly (1316035) is made up of (A6-A1) the 1 Watt Amplifier
Board (1310282), (A6-A2) the BL881 Single Stage Amplifier Board (1314882, and (A6-
A3) the Dual 888A Pallet Assembly (1315347). The ALC Board (1315006) is also part of
this assembly. The entire amplifier assembly has approximately 36 dB of gain.
(A6-A1) 1 Watt UHF Amplifier Module (1310282)
This board is normally operated at a power of 200 mW pk sync or lower. It consists of
two AH202 MMICs operating in parallel. The board is powered by +12 VDC and has no
adjustments. The amplifier module has a gain of approximately 17 dB.
(A6-A2) BLF881 Single Stage Amplifier Board (1314882)
This board consists of a single stage amplifier operating at +48 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 using pots R2 and R3. The
Diode CR1 provides temperature compensation for the transistor. The transistor will
output over 40 Watts pk sync, but is typically used in a driver application at much lower
output powers. The Directional Coupler U2 provides a 20 dB down sample of the RF
output at the SMA Jack J4.
(A6-A3) Dual BLF888A Pallet Assembly (1315347)
This board is a UHF LDMOS power amplifier consisting of two pair of power transistors
operating in parallel. The board operates on a power supply voltage of +48VDC. The
voltage regulator U1 steps down the voltage to provide a bias voltage to each pair of
transistors. The diodes CR1 and CR3 are used to temperature compensate the bias
voltage that is applied to the Q1 and Q2 RF transistor pairs. As the transistor pairs heat
up, the diodes also heat up, causing the voltage across them to drop, lowering the bias
voltage to the RF transistors so that the voltage remains constant with device
temperature.
The board has a gain of approximately 18 dB. The RF input to the board is split by HL1
and each output is connected through hybrid couplers to the Q1 and Q2 transistor pairs.
The amplified outputs of the transistor pairs are connected through hybrid couplers to
the combiner HL2.
The transistor pairs are operated in quadrature, with one transistor pair operating 90°
out of phase of the other, which provides for a very good return loss across the UHF
band on both the input and output of the board.