Specifications

Section 4 - ADJUSTMENTS and OPTIONS

4-1. INTRODUCTION. - This section describes operator adjustments and the selection of the

internal options. For a discussion of the microprocessor-controlled functions (Channel ON/OFF,

FREQUENCY and compandor IN/OUT) please refer to Section 3-4. For a discussion of line

voltage selection, please refer to Section 2-5. Throughout this section, the terms PPL and APL

are used in referring to audio levels. For a thorough discussion of these terms and equivalent

CCITT test levels, please refer to Appendix A.

The operator adjustments are located on the front panel on both the transmitter and receiver. The

transmitter adjustments consist of subcarrier level and deviation trims. The receiver adjustments

consist of squelch threshold and audio output level trims.

The internal options include selection of audio levels and impedances, emphasis type (with

companding OUT), and the receive highpass filter. These options are configured at the factory

prior to shipment as follows:

Audio Input/Output Levels .............. +18 dBm

Audio Impedance ......................... 600 Ω

Emphasis Type ............................75 µS

Receive Highpass Filter .................... IN

These settings will be suitable for the majority of applications, and should only rarely need to be

changed.

4-2. RECOMMENDED TEST EQUIPMENT.

Note: The equipment listed below comprises all of the test equipment mentioned in this

section. It is not necessary to have all of these items on hand to perform the adjustments.

Refer to each subsection for the specific items needed.

Item Manufacturer & Model

Audio Analyzer ................... HP 8903B

Modulation Monitor .............. Marconi TF2300A

AC Voltmeter ...................... Fluke 8920A

Spectrum Analyzer ................HP 8552B/8553B

Frequency Selective VM ........ HP 3586C

Oscilloscope .........................Tektronix 2235

75 Ohm 1% BNC Termination .. Any

Equivalent equipment is acceptable. The specifications of the alternate instrument

should be significantly better than the accuracy of the measurement made.

450 Operation Manual Rev A Page 22 8/26/99