Voltage Regulator; Alignment Procedure; Standard Input Signal; Rf Alignment - RF Technology R220 Operation And Maintenance Manual

5.11 Voltage Regulator

5.11 Voltage Regulator
The dc input voltage is regulated down to 9.4 Vdc by a discrete regulator circuit. The
series pass transistor Q20 is driven by error amplifiers Q21 and Q22. Q23 is used to
start up the regulator and once the circuit turns on, it plays no further part in the
operation.
This circuit is short circuit and overload protected. It provides much better line
isolation and lower dropout voltage than can be obtained with current integrated
circuit regulators.
6

Alignment Procedure

The following procedures may be used to align the receiver for optimum
performance. Normally only RF alignment will be required when changing
frequencies. IF alignment should only be necessary after repairs on that part of the
circuit.
Reference oscillator or TCXO calibration may be required periodically due to crystal
aging. The aging should be less than 1 ppm/year.
6.1

Standard Input Signal

RF Signal Generator
50 Ω output impedance
Frequency range 215 - 240 MHz
FM modulation at 1KHz
1.5KHz peak for 12.5KHz channel spacing

6.2 RF Alignment

Alignment Frequency
215 - 240 MHz range
Page 16
5 CIRCUIT DESCRIPTION
221.000 MHz
RF Technology R220