5-18
888-2595-001
12/20/11
WARNING: Disconnect primary power prior to servicing.
Section 5 Maintenance and Alignments
ZX Series
f
0
= the original test frequency in megahertz
EXAMPLE:
If the transmitter lists a coupling of -50.0 dB at 98 MHz, it will have a coupling of -
49.56 dB at 103.1 MHz
-49.56 dB = -50.0dB +
.
0866 * (103.1 – 98)
The coupling factor is entered as an “offset” into the average power meter to obtain a
direct metering reading in watts.
5.4.3
Reverse Power Meter Calibration
Use this procedure to calibrate the transmitter reverse power meter only if its
measurement calibration is in doubt. This adjustment does not require routine
calibration. Refrain from disturbing the reverse meter calibration if the reverse power
measured by the external precision measurement source is less than 1% of the
transmitter nameplate power level. In such cases, special steps may be required to
create a temporary high reverse power reading.
Tools required:
Precision directional coupler (reverse port) and average power meter or
Calibrated through-line type wattmeter (reverse direction)
Small adjustment screwdriver
STEP 1
Obtain calibrated reading of transmitter reverse power from external
precision measurement source. If reading is less than 1% of transmitter
rated power, perform these steps to generate a sufficient reading.
a.
ZX2500 / ZX3750 / ZX5000: lower transmitter power to 2% of name-
plate rating, switch off transmitter, break output transmission line,
switch on transmitter. Reflected power = forward power = 2%.
b.
ZX7.5 / ZX10: lower transmitter power to 2% of nameplate rating,
swap REVERSE METER lead and SMA RF load on two ports of
reverse meter directional coupler at final system output. Reflected
sample is now monitoring forward power = 2%.
STEP 2
If PA chassis meter is to be calibrated, select reverse power reading on
amplifier front panel meter via meter select pushbutton, open front door,
and locate reverse power calibration potentiometer (METER CAL -
REV) on controller board. Adjust potentiometer until deisred reading is
obtained on meter.
Содержание ZX10
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Страница 80: ...3 12 888 2595 001 12 20 11 WARNING Disconnect primary power prior to servicing Section 3 Operation ZX Series ...
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Страница 174: ...7 12 888 2595 001 12 20 11 WARNING Disconnect primary power prior to servicing Section 7 Parts List ZX Series ...