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. 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 composite output level trims.
The only internal option on the 455 is the selection of the receive high pass filter. This option
is set at the factory to IN, and should only changed if the system is used below 4.0 MHz in the
absence of video.
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
Ω
1% BNC Termination .............. Any
25
Ω
1% 50
Ω
to 75
Ω
series adapter .... Any
Equivalent equipment is acceptable. The specifications of the alternate instrument should
always be significantly better than the desired accuracy of the measurement to be made.
455 Operation Manual
Page 26
6/23/98
