Specifications

2. With the measuring instrument properly tuned to the frequency of the channel to
be adjusted, set the IF (subcarrier level) screwdriver adjustment on the front
panel for the proper level for your system.
3. Adjust the second channel of the 450 Transmitter after re-tuning the measuring
instrument to the appropriate frequency.
4-5.Deviation Adjustment (DEV). - The 450 Transmitter is designed to operate with
a peak deviation of the subcarrier of 75 kHz (150 kHz peak-to-peak) for an audio
input corresponding to Peak Program Level (PPL). The front panel DEV
adjustment is provided to compensate for minor variations in incoming audio signal
strength, and is not intended to provide for operation at deviations other than the
450's specified deviation. The deviation may be accurately set using either a
modulation meter or a spectrum analyzer; choose the method you find most suitable.
A. Deviation Adjustment Using a Modulation Meter.
1. If the modulation meter has a high impedance input, connect it to the baseband signal at
any convenient point after the insertion of the subcarrier to be adjusted. If the
measuring instrument has a low impedance (i.e., 75 or 50 ohm) it is necessary to
connect the instrument to an isolated monitor point in order to prevent the additional
load presented by the low impedance input from affecting the levels of the signals
on the baseband (this level change has no direct effect on the adjustment of
subcarrier deviation, and may be ignored if there are no active receive sites that may
be adversely affected).
2.Connect an audio signal generator to the T, R, and ground connections of the channel to
be adjusted. The audio signal generator should be set to provide a 1 kHz test signal
at Peak Program Level.
3.With the modulation meter properly tuned to the frequency of the channel to be adjusted,
adjust the front panel screwdriver adjustment DEV until the modulation meter
indicates 75kHz peak deviation (150kHz peak-to-peak).
4.Adjust the second channel of the 450 Transmitter after re-tuning the modulation meter to
the appropriate frequency, and transferring the audio signal generator to the T, R,
and ground connections of the second channel.
450 Operation Manual Rev A Page 24 8/26/99