Thales 421, Эксплуатация и обслуживание, Страница: 244 / 256

LLZ 421
Alignment Procedure LLZ−2F (LPD) Operation and Maintenance
ILS 420
8−14
Ed. 07.08 SOAC
8.4.1 Adjustment Procedure of Aerial Channels
See Fig. 4−8, 8−2, 8−3, 8−5.
NOTE: The signal path used within the SOAC is set to 11−12 on J19 of SOAC.
(used for LPD antenna with CU part no. 120631−0001; alternative setting is 9−10 , use procedure and path of section 5.4.1)
Do not use +15 dB amplifiers in the SOAC input path. The signal must not be overdrived.
8.4.1.1 CRS Posn. Channel
(Input connector J9)
− Connect oscilloscope to TP51 and TP59 (GND). Measure output level. Adjust IF gain to achieve
approx. 3.6 Vpp output: perform first coarse alignment removing or inserting attenuators with
JP16,17 or J18,19; perform fine adjustment with R90 and finally R377.
8.4.1.2 CRS Width Channel
(Input connector J7)
− Connect oscilloscope to TP63 and TP59 (GND). CRS CSB path is set; adjust with R379 to achieve
1.5 Vpp at TP63. Connect oscilloscope to TP13: Perform first coarse alignment of CRS SBO path
removing or inserting attenuators with JP7,8 or JP9,10 and fine adjustment with R43 to achieve
0.16 Vpp. Check relative CSB − SBO phase with oscilloscope, measure between TP63 (CSB) and
TP13 (SBO), see Figs. 4−8, 8−3, 8−5. Adjust with R166 to 180°. If need be readjust R379 for CSB
component level. CRS Width DDM is defined by CSB/SBO ratio set with mainly R383 and R379.
Finally adjust output level with R382 to approx. 3.6 Vpp at TP53.
8.4.1.3 CLR Width (1) Channel
(Input connector J18)
− Connect oscilloscope to TP39 and TP59 (GND). Measure output level. Adjust IF gain to achieve
approx. 3.6 Vpp output: perform first coarse alignment removing or inserting attenuators with
JP37,38 or J39,40; perform fine adjustment with R286 and finally R343. Phase adjustment with
R353 is factory set and not needed. R345 remains in mid position.
8.4.1.4 NFM Channel
(Input connector J10). Refer also to 8.4.3.4.
− Connect oscilloscope to TP41 and TP59 (GND). Measure output level.
Adjust IF gain to achieve approx. 3.6 Vpp output: perform first coarse alignment removing or insert-
ing attenuators with JP22 or J23,24; perform fine adjustment with R105.
IF gain set
R43
CRS SBO in
J7
R377
out
CRS Posn
TP8
R372
JP7
JP9,10
in
TP51
input attenuation
−5 dB
Output level adjust
−10 dB −10 dB
3.6 V
TP62
JP8
setting depends on local condition
R382
CRS Width
TP53
Output level adjust
TP66
TP63
R379
out
3.6 V
IF gain set
R90
CRS CSB in
J9
TP16
JP16
JP18,19
in
input attenuation
−5 dB −10 dB −10 dB
JP17
TP64
R383
TP13 TP10
Phase adjust
fixed
phase
R166
nom. 90° lag
TP11
preset to mid*
factory field
preset to mid*
not used
preset to mid*
preset to mid*
setting depends on local conditions
−/+
+15 dB
+15 dB
IF gain set
R105
NFM Posn.
J10
out
NFM Posn.
TP18
JP22
JP23,24
in
TP41
input attenuation
−5 dB
Output level
−10 dB
3.6 Vpp
set ting depends on local conditions
* initial setting
TP59, TP30 GND
+15 dB
ca. 0.6Vpp
IF gain set
R286
CLR Width in
J18
TP31
out
CLR Width
TP71
R343
JP37
JP39,40
in
TP27
TP39
TP25
input attenuation
−5 dB
Output level adjust
−10 dB −10 dB
Phase adjust (not used)
3.6 Vpp
R345
R353
JP38
TP26
set to mid position* setting depends on local conditions set to mid position: 3.7k
factory
+15 dB
ca. 0.7Vpp
+ −
ca. 3.2 Vpp
ca. 0.16Vpp
ca. 1.5Vpp
ca. 0.16Vpp
Fig. 8−3 Adjustment of detector channels for aerial monitoring
Ed. 01.10