5.14.3 45 kW Transmitters
For the 45 kW transmitters with 10% aural, each RF chain is
calibrated at 2.25 kW, and the combined transmitter output will
be 1.125 kW. Thus, the same procedure, controls and test points
are used as outlined in the 30 kW 20% aural calibration section,
except that the controls are adjusted for 2.5 volts when the
combined power measured is 1.125 kW.
For 20% aural, the aural path consists of three aural chains. Thus,
the calibration process is the same as the visual power calibration
process, except that an aural input signal and the combined aural
output power readings in the table below are used. Note that unit
1 houses aural PA’s A & B, and unit 2 houses aural PA C.
Display the aural PA front panel screen and energize each of the
three aural RF chains separately (disable the appropriate driver
module by squeezing its front panel switch, in order to de-ener-
gize a particular chain). Measure the combined aural output
power, looking for the values listed in table below. Next, adjust
R-60 for the auralRF chain ‘A’(when that RF chain is energized)
on the slave controller unit 1 for 2.5 volts at TP-3. The display
should read 3.0 kW. Repeat the procedure for RF chains ‘B’and
‘C’and adjusting R-74 for 2.5 volts at TP-4 for RF chain ‘B’and
adjustingR-60ofunit2forRFchain‘C’.
Aural Power Out Versus
Aural RF Chain Power
Aural Chains
Energized
Combined Output Power
ABC
300 1.0
030 1.0
003 1.0
330 4.0
303 4.0
033 4.0
333 9.0
5.14.4
60 kW Transmitters
For 60 kW transmitters with 10% aural power, energize each
aural RF chain separately and adjust the power to obtain 1.5 kW
at the combinedoutput of thetransmitter.Displaythe appropriate
aural PA page on the front panel screen. Connect a high imped-
ance voltmeter to TP-3 on the slave controller board associated
with that RF chain and adjust R-60 to 2.5 volts. The aural RF
chain front panel display should read 3 kW.
If the 20% aural power option is installed, energize one of the RF
chains in one of the cabinets and set the combined output power
to 0.75 kW. Next, adjust R-60 on the slavecontroller for 2.5 volts
at TP-3. The aural RF chain display should read 3.0 kW. De-en-
ergize that aural RF chain and energize the other chain in that
cabinet and repeat the procedure except adjusting R-74 at TP-4.
Repeat the process for the other aural PA cabinet.
5.15 Reject Load Calibration
This section covers calibration of the reject load power peak
detectors for those transmitters with external reject loads.
5.15.1
20 kW Transmitters
5.15.1.1 Visual Reject Load
Energize one visual PA cabinet and apply a blanking and sync
video signal. Drive the cabinet to 10 kW peak sync and adjust
calibrate control R-95 on the main controller for 2.5 Volts at
TP-5. The display should then read 5.0 kW on the visual meter
page 2. De-energize that cabinet and energize the other. The
display should show the same reading.
5.15.1.2 Aural Reject Load
An external reject load is used in the aural combiner system as
well. Energize one of the RF chains and set the combined output
power to 0.5 kW. Next, adjust R-103 on the main controller for
2.5 volts at TP-7. The aural RF reject power display should read
0.5 kW. De-energize that aural RF chain and energize the other
chain, checking the calibration using the same procedure.
5.15.2
30 kW Transmitters
5.15.2.1 Visual Reject Load
Energize one visual PA cabinet and apply a blanking and sync
video signal. Drive the cabinet to 15 kW peak sync and adjust
calibrate control R-95 on the main controller for 2.5 Volts at
TP-5. The display should then read 7.5 kW on the visual meter
page 2. De-energize that cabinet and energize the other. The
display should show the same reading.
5.15.2.2 20% Aural Reject Load
If the 20% aural power option is installed, an external reject load
is used in the aural combiner system as well. Energize one of the
RF chains and set the combined output power to 1.5 kW. Next,
adjust R-103 on the main controller for 2.5 volts at TP-7. The
aural RF reject power display should read 1.5 kW. De-energize
that aural RF chain and energize the other chain, checking the
calibration using the same procedure.
ADR CABINET SWITCH POSITION
87654321
01 Aural1 xxxooooc
02 Aural2 xxxoooco
03 VisualA xxxooocc
04 VisualB xxxoocoo
05 VisualC xxxoococ
06 VisualD xxxoocco
c= CLOSED o=OPEN x=UNUSED
Table 5-6. Slave Controller S1 Settings
Section V - Maintenace
Rev. B: 1/11/1999 888-2365-001 5-9
WARNING: Disconnect primary power prior to servicing.
To Next Page
Loading...
