8. 21.4 MHz Bandwidth Filter Adjustments

8.21.4 MHz Bandwidth Filter Adjustments

Reference IF-Display Section

A4A4 Bandwidth Filter

A4A8 Attenuator-Bandwidth Filter

Related Performance Tests

Description

IF Gain Uncertainty Test

Resolution Bandwidth Switching Uncertainty test

Resolution Bandwidth Selectivity Test

First the LC Filters (100 kHz to 3 MHz bandwidths) on the A4A4 Bandwidth Filter are adjusted. The crystal filter poles (3 kHz to 30 kHz bandwidths) are then adjusted for center and symmetry by bypassing all but one pole at a time and adjusting the active pole.

Next, the LC filters and the crystal filter poles on the A4A8 Attenuator-Bandwidth Filter are adjusted in the same manner as on the A4A4 Bandwidth Filter.

Last, the 10 dB and 20 dB attenuators on the A4A8 Attenuator- Bandwidth Filter are adjusted for the proper amount of attenuation. This is done by connecting the CAL OUTPUT signal to the RF INPUT through two step attenuators, keying in the necessary reference level to activate the 10 dB and the 20 dB control lines, adjusting the step attenuators to compensate for the attenuation, and adjusting the attenuators for the proper amount of attenuation.

SPECTRUM ANALYZER

I

DIGITAL VOLTMETER

rm

1OdB STEP IdH STEP ATTENUATOR ATTENUATOR

Figure 3-40. 21.4 MHz Bandwidth Filter Adjustments Setup

Adjustments 3-77