TB 9-6625-2171-35
23. MKR BCN
a. Performance Check
(1)
Set GLIDE SLOPE PWR switch to OFF and MKR BCN PWR switch to
ON.
(2)
Connect measuring receiver power sensor module to TI J1. Position
measuring receiver controls to measure AM.
(3)
Connect frequency counter to measuring receiver modulation output.
(4)
Press and hold MKR BCN yellow (1300 Hz) pushbutton. If frequency
counter does not indicate between 1274 And 1326 Hz, perform b(1) below. Release MKR
BCN yellow pushbutton.
(5)
Press and hold MKR BCN blue (400 Hz) pushbutton. If frequency counter
does not indicate between 392 and 408 Hz, perform b(2) below. Release MKR BCN blue
pushbutton.
(6)
Press and hold MKR BCN white (3000 Hz) pushbutton. If frequency counter
does not indicate between 2940 and 3060 Hz, perform b(2) below. Release MKR BCN
white pushbutton.
(7)
Press and hold MKR BCN yellow pushbutton. If measuring receiver does
not indicate an amplitude modulation between 90 and 100 percent, perform b(3) below.
Release MKR BCN yellow pushbutton.
(8)
Repeat (7) above for MKR BCN blue pushbutton.
(9)
Repeat (7) above for MKR BCN white pushbutton.
(10)
Disconnect frequency counter from equipment setup and connect audio
analyzer to modulation output.
(11)
Press and hold MKR BCN yellow pushbutton. Measure distortion. Audio
analyzer will indicate less than 15 percent. Release MKR BCN yellow pushbutton.
(12)
Repeat (11) above for MKR BCN blue pushbutton (400 Hz).
(13)
Repeat (11) above for MKR BCN white pushbutton (3000 Hz).
b. Adjustments
(1)
Adjust A6R110 (fig. 3) until frequency counter indicates 1300 Hz (R).
(2)
Repeat a(4) and b(1) above and adjust A6R110 for best in-tolerance condition.
(3)
Adjust A6R119 (fig. 3) until measuring receiver indicates an amplitude
modulation of 95 percent (R). If required, adjust A6R119 for best in-tolerance condition for
the three modulated frequencies.
24. Final Procedure
a. Deenergize and disconnect all equipment and reinstall TI in its case.
b. Annotate and affix DA label/form in accordance with TB 750-25.
