A-A-50755
maximum and is controlled by a relay operated switch on the test fixture. The delay switch causes illumination of a light indicator, and delivers 28VDC power to four modules in the Unit Under Test (UUT) and the azimuth and elevation of the control head assembly. A slo-blo fuse for the 28VDC input will be used to protect the test fixture and UUT. The test fixture can also receive and monitor the UUT output signals.
b. Receiving and monitoring of UUt output signals. The UUT output signals will load into the test fixture to an azimuth current sink and an elevation current sink. The current sinks are made up two parallel connected 8.66 OHM load resistors at 120 watts. There will be three pairs of voltage monitoring tip jacks (isolated) which will be measured from a digital multimeter. One pair is used to monitor the input voltage and the other two are used to monitor the UUT output signals. The UUT output signals should be measured in parallel with the resistors. A thermal protection switch will remove power from the test fixture if the heat sinks temperature rises above 203 degrees Fahrenheit. A cooling fan will be used to protect the azimuth and elevation heat sink load resistors. The test fixture will supply a grounding clip, 12 inches from the front panel, to assure UUT grounding capability.
c. Azimuth and elevation drive controls. Two toggle switches one for elevation control and another for azimuth control signals are located at the front panel. The elevation switch should indicate up and down for vertical antenna control and the azimuth switch should indicate CW or CCW for horizontal antenna control. The control signals are 28VDC output and are supplied to the UUT through the connector.
d. Plug in connector. The plug in connector military standard MIL-C-38999, P/N MS27472T14B-18S, 359-0689-010, has a 12 inch cable from the front panel of the test fixture, and its pin locations as shown in figure 1-1 and pin assignment as shown in table 1-1. The four module inputs A1, A2, A3, A4, are in pins N, R, M, L, E, G, D, C. The antenna control drives are in pins P, S, F, H, and the UUT signal inputs are in pins A, B, J, K.
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