Section V
Paragraphs 5-7 to 5-9
5-8. GLIDE SLOPE 3-DB ACCURACY CHECK.
CHECK.
a. Perform steps a and b of paragraph 5-7.
a. Connect Signal Generator SG-2/GRM-4 through a
6-db, 53-ohm attenuator to an AN/ARN-18 glide slope
b. Modulate the SG-2/GRM-4 with a 2-db up glide
receiver equipped with Course Indicator ID-249A/
slope signal and adjust the receiver for 65 micro-
ARN. See B of figure 5-2 for connections.
amperes crosspointer current.
b. Set the frequencies of the signal generator and
c. Perform steps d and e of paragraph 5-7.
receiver to 332.0 mc and adjust the SG-2/GRM-4 out-
put level for 500 microvolt.
d. Set AUDIO SELECTOR to GLIDE SLOPE, NAV-
c. Modulate the SG-2/GRM-4 with a zero db glide
GS switch to GS, MICROVOLTS dial at 1000, and
LOC-GS control to the top line of the left segment
slope signal and adjust the receiver for zero cross-
pointer current. Refer to receiver handbook for lo-
(3-db up glide slope signal). The crosspointer cur-
rent should be 97.5 18 microamperes.
cation of this adjustment.
d. Substitute Signal Generator SG-13/ARN for the
e. Repeat steps a through d above for a 3-db down
glide slope signal.
SG-2/GRM-4 and set its frequency to 332.0 mc. See
A of figure 5-2 for connections.
5-9. Failure of the signal generator to meet the above
e. Allow the SG-13/ARN to warm up for 15 minutes
VOR, TONE LOC, and GS accuracy requirements
and red line the meter.
usually indicates that one or more of the audio signals
involved is not set to the correct frequency or per-
f. Set AUDIO SELECTOR to GLIDE SLOPE, NAV-
centage modulation. Excessive distortion can also
GS Stitch to GS, MICROVOLTS dial at 1000, and
cause inaccuracy. Table VII lists the frequency tol-
LOC-GS control to the center of the white segment
erances and total harmonic distortion of the audio fre-
(on course). The crosspointer current reading should
quencies and VOR and r-f signal accuracies, that are
be 0 12 microamperes.
permissible.
