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Page Title:
Coupler, Antenna CU-890/URM-8~for Vertical Antenna |
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|  tripod mast serves as the mounting
d. C o u p 1 e r, Antenna CU-890/URM-8~
p o s t for the CU-890/URM-85. In-
connect the signal generator from the test
s e r t the s t u d assembly at the
setup (fig. 79) and use the method of check-
bottom plate of the CU-890/URM-
i n g performance of this minor component
85 (fig. 81) all the way over the pro-
a s outlined in paragraph 43c, steps 63
truding post, and tighten the thumb
through 69, TM 11-6625-351-12.
s c r e w provided on the antenna
c o u p l e r stud assembly. Insert the
(1) In mounting the ground plane (fig.
f i v e series-connected lengths of
s e c u r e mechanical fit. Insert the
M a s t Section AB-21/GR into the
ferrule assembly at the top of the
p r o t r u d i n g post at the tip of the
t r i p o d mast through the hole pro-
CU-890/URM-85, and proceed with
v i d e d on the ground plane hinged
t h e equipment performance check-
b r a c k e t ; then secure the ground
l i s t as outlined in paragraph 43c,
steps 63 through 69, TM 11-6625-
p l a n e by rotating the two l/4-turn
fasteners on the higned bracket into
351-12.
their mating spring receptacles,
(3) If trouble is encountered in testing
any one of the six bands, refer to
provided on the tripod plate. If the
t h u m b s c r e w s , one each located at
t h e schematic diagram (fig. 37),
and to the exploded view (fig. 81).
t h e ends of the antenna tilt rods
A v o i d unnecessary disassembly;
follow the exploded view and disas-
are frozen, refer to the insert view
sembly only to the extent necessary
i n the lower right corner of this
illustration for disassembly and
to correct the trouble. Possible
replacement procedures. If the
s o u r c e s of trouble are:
(a) O p e n o r s h o r t e d f e r r i t e c o r e
ground plane cannot be tilted from
i t s horizontal position on the tri-
step-down transformers T1101
pod, suspect trouble within the
t h r o u g h T1106, mounted on ter-
m i n a l board assembly TB1101.
a n t e n n a tilt bracket and refer to
(b) Band switch S1101 fails to make
t h e insert view at the left center
c o n t a c t in any or all of the six
a r e a of the illustration for disas-
p o s i t i o n s . Check for continuity
sembly a n d replacement pro-
i n all switch positions (fig. 37
cedures.
N o t e : The three turnlock fastener recep-
and 81).
t a c l e s at the center of the ground plane
(c) Open circuit in the impulse gen-
a r e not used with Coupler, Antenna CU-
erator injection network, con-
890/URM-85; they are provided for use with
sisting of series resistor R1101
the di scone (broadband) antenna Also, the
t h e four tumlock fastener studs (fig. 82)
and shunt resistor R1102 (fig. 37
l o c a t e d one each at the comers of the
and 81). Do not attempt to replace
ground plane serve no mounting function;
the individual resistors; they are
they are provided for secure] y storing the
h o u s e d within green color-coded
ground plane within Case, Radio Interfer-
ence Measuring Set Group CY-3094/URM-85.
c o n n e c t o r assembly J1102 and
(2) After the ground plane has been
are inaccessible; if trouble is
s e c u r e l y mounted to the antenna
i s o l a t e d to this circuit, replace
t r i p o d , the protruding post on the
t h e entire connector assembly.
168
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