Motorola MTR2000 T5544 Instruction / Field Service Manual page 322

VHF Duplexer Module
4.
Tuning High Notch Loop Assemblies
1.
Set up test equipment as
shown, connecting to cavity
#1.
2.
Use tuning tool to adjust
trimmer screws for cavity #1
to obtain minimum reading
on millivoltmeter. (Adjust
trimmer screws equally to
obtain minimum. Reduce
the range on the millivoltme-
ter as necessary to reach
true minimum reading.)
3.
Repeat steps 1 and 2 for
cavities #2 and #3.
5.
Tuning Low Notch Loop Assemblies
1.
Set up test equipment as
shown.
2.
Use tuning tool to adjust
trimmer screw for cavity #4
to obtain minimum reading
on millivoltmeter. (Adjust
trimmer screw to obtain
minimum. Reduce the
range on the millivoltmeter
as necessary to reach true
minimum reading.)
3.
Repeat steps 1 and 2 for
cavities #5 and #6.
4.
Reconnect the cables on
the duplexer. Make sure
that the cables are
returned to their original
position on the Duplexer.
Figure 9.
14
6dB In-line
pad (50Ω)
Cavities
1 2 3 4
Trimmer Screws (2)
"T" Connector
Cavities
1 2 3 4
6dB In-line
pad (50Ω)
VHF Duplexer Field Tuning Procedure (Continued)
Boonton 92E RF
Millivoltmeter
Range set to +10dBm
5 6
Loop Assemblies
HP8656B Signal Generator
Frequency set to Rx or Tx frequency,
whichever is HIGHER.
Output Level set to +10dBm.
Boonton 92E RF
Millivoltmeter
Range set to +10dBm
5 6
Loop Assemblies
Trimmer Screw
"T" Connector
HP8656B Signal Generator
Frequency set to Rx or Tx frequency,
whichever is LOWER.
Output Level set to +10dBm.
68P81085E16-B
09/30/05