Scope Intensity Squelch . The scope intensity squelch circuitry consists of SQUELCH ADJ A2A1R25, amplifier
A2A1Q4, amplifier A2A1Q3, transformer A2A1T3, detector A2A2CR4, CR5, squelch switch A2A2Q1, and SCOPE
INTENSITY control R3. The emitter-follower output of vertical amplifier A2A1Q2 is sampled through SQUELCH ADJ
A2A1R25 and is applied to amplifier A2A1Q4, which raises the signal to the required level. Amplifier A2A1Q3 is coupled
through high-voltage isolation transformer A2A1T3, and provides an output directly proportional to the output of vertical
amplifier A2A1Q2, T2. Transformer A2A1T3 provides a balanced input to detector A2A2CR4, CR5, which provides the
dc input to squelch switch A2A2Q1. Squelch switch A2A2Q1 parallels the wiper and negative most side of SCOPE
INTENSITY control R3. When the level in the vertical channel falls below a preset value, squelch switch A2A2Q1
conducts less, applying a higher negative potential to the scope intensity grid, and squelching the scope pattern.
Similarly, when the level in the vertical channel rises above a preset value, the squelch switch conducts more, restoring
the scope pattern to the screen.
Scope Power Supply . The scope power supply consists of dc-to-ac Inverter A2Q1, Q2, T1, which converts +22 volts
dc into 1,000 volts peak to peak for rectification by voltage doubler rectifier A2A2CR1, CR2, which supplies 1,000 volts
dc to the scope voltage divider.
Section VI. STAGE ANALYSIS, TRANSMIT SIGNAL PATHS
This section presents detailed stage analysis of the modem transmit circuits, including transmitter module A3 and loop
battery module A5. Wherever possible, the discussion of the circuits is limited to a module basis. Figure FO-8 is the
overall schematic diagram of modem. Refer to it as necessary during the following discussion for the details of signal
paths between modules and for switch connections.
1-39. LOOP BATTERY MODULE A5
The loop battery module analysis is given In paragraphs 1-40, 1-41, and 1-42 and consists of two Identical dc-to-ac
Inverter and current regulator circuits, a receive sensing circuit, a send sensing circuit, and associated switching circuits.