User Manual

Page 16 RF Technology R220

5.11 Voltage Regulator

5 CIRCUIT DESCRIPTION

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

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 221.000 MHz