User's Manual

Innovator CHV400BTD ATSC Transmitter Board Descriptions
Technical Manual, Rev. 0 56
The upconverter has two local oscillators, LO1 and LO2. The LO1 oscillator consists of
U1, U2, U5, U6 and amplifiers U3 and U4. The LO1 oscillator operates at 1 GHz for 44
MHz IF inputs and is used to convert the signal to 1044 MHz. In 36 MHz IF systems, this
oscillator circuit operates at 1.008 GHz. The Red LED DS4 will light if the PLL for the
LO1 oscillator is not locked.
The second LO, LO2, consists of two VCOs, U26 and U31, that are used to generate the
second LO. One VCO operates from 1.1-1.5 GHz and the second from 1.5-1.9 GHz. The
Red LED DS2 will light if the PLL for the LO2 oscillator is not locked.
Both of the LOs, LO1 and LO2, are locked to an on board 10 MHz VCXO. The 10 MHz
VCXO circuit consists of U36, U39, the VCTCXO Y1 and associated components. When
an external 10 MHz signal is applied to J10 on the board, the internal VCXO is locked to
the external 10 MHz, otherwise, it is free-running. The Red LED DS6 will light if an
External 10 MHz reference is present. The Red LED DS3 will light if the PLL for the 10
MHz oscillator is not locked.
Pin AttenuatorJ1
RF Input
Input Loss
Detector
Auto/Man Select
ALC
TP4
Mute from
Control Circuit
J2
RF Output
TP1
Overdrive Detect
Output Power
Reflected Power
Input Power
Reference
(A5) ALC Board, Innovator CX Series (1308570)
The ALC Board, Innovator CX Series, is used to control the RF drive power to the RF
amplifier chain in the CHV200B system. The board accepts an 8-VSB RF input signal at
a nominal input level of -3 dBm average power and amplifies it to whatever drive level is
necessary to drive the final RF amplifier in the tray to full power. The input signal to the
board at J1 is split by U4, with one half of the signal driving a PIN diode attenuator, DS1
and DS2, and the other half driving a detector, U13, that is used to mute the PIN
attenuator when there is no input signal. The output of the PIN attenuator is sent to two
cascaded amplifiers, U2 and U3, which are capable of generating +10 dBm average
power from the board at J2.
The PIN attenuator is driven by an ALC circuit or by a manual fixed voltage bias,
depending on the position of switch S1. When the switch is pointing to the left, looking
from the front of the tray, the ALC circuit is enabled. When the switch is pointing to the
right, the ALC circuit is disabled and the PIN attenuator is controlled through the Manual