There are two independent BDHI selector panels (Figure 1-14-18), one located in the radio and navigation control panel for the pilots BDHIs, and the other on the sensor station for the TACCO’s BDHI. They incorporate six push-button type switches with display screens, and these control the type of information to be displayed on their respective BDHI indicators.
a. When ARN/TAC is depressed, bearing information from the LF ADF is displayed by pointer No.1, and TACAN or VOR information is displayed by pointer No.2 and the three-digit counter.
b. When ASN is depressed, AN/ASN-123C readout information is displayed by pointer No.1 and the three-digit counter, and TACAN or VOR bearing information is displayed by pointer No.2.
c. When ARA/TAC is depressed, bearing information from the facility selected on the ARA selector panel is displayed by pointer No.1 TACAN or VOR information is displayed by pointer No.2 and the three-digit counter.
d. The TRUE switch, when depressed, will allow true heading information from the GHARS system to be displayed on the applicable BDHI cards. The bearing pointers will show true bearing.
e. The TRK switch, when depressed, will allow ground track information from the bearing ground track module of the tactical navigational computer to be displayed on the applicable BDHI cards. The bearing pointers will show true bearing.
f. The MAG switch, when depressed, will allow magnetic heading from the synchro signal amplifier to be displayed on the applicable BDHI cards. The bearing pointers will show magnetic bearing.
g. Each BDHI selector panel also incorporates a two-position toggle switch labelled DAY and NIGHT. When in the DAY position, 28 VDC is fed directly to the lights to give maximum illumination. When in the NIGHT position, the intensity of the lighting for the BDHI selector panel, located on the radio and navigation control panel, is fed through a dimmer control identified CONSOLE AND PANEL LIGHTS on the overhead switch panel. The intensity of the lighting for the BDHI selector panel, on the sensor station, is controlled through the TACCO STA LTS rheostat on the switching and dimming panel.
