User's Manual

Innovator CU0TD-1/CU0RD-1 – CU4TD/CU4RD ATSC Board Descriptions
Transmitter/Regenerative Translator
Instruction Manual, Rev. 2 112
(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 (1316636) – Used in CU0TD/RD-3
The (A6) Amplifier Assembly (1316636) is made up of (A6-A1) the 1 Watt Amplifier
Board (1310282), (A6-A2) the BLF881 Single Stage Amplifier Board (1314882), and
(A6-A3) the Dual BLF 881 Pallet Assembly (1316084). The ALC Board (1315006) 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 that consists of two AH202 MMICs operating in
parallel. The board is powered by +12 VDC and has no adjustments. The amplifier has a
gain of approximately 16 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 BLF881 Pallet Assembly (1316084)
This board consists of a two single stage amplifiers operating in parallel. The board has
an overall gain of approximately 18 dB. The RF input to the board connects to U3 a
hybrid splitter which produces two equal outputs. One output of the splitter is fed thru a
matching and response network to the gain stage, which consists of the LDMOS
transistor Q1 operating in Class AB. C11 is adjustable for best response.