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Adjustments
Model 8902A
Adjustment 5-LO
Doubler Output Power and Balance
Reference
Service Sheet 17.
Description
The power from the LO is monitored with a power meter while the LO is stepped through its
doubler band. The bias and coupling components are changed as necessary to obtain the required
power output. The
LO
is then monitored on a spectrum analyzer as the LO is swept slowly
over
its
doubler band. The doubler balance is adjusted for minimum
Yz
and
harmonics of the doubled
frequency.
NOTE
Exct>ssive siihharmonics
can caiisc
the LO
to
tirne
to
a
wrong.fiqiicncy whcn
airtomatically
[iining.
Equipment
Sensor Module
.................................................................
HP
1 1722A
RF Spectrum Analyzer
......................................................
H P 8559A/182T
Procedure
NOTE
In rhti.following
proctdiirc,
a
power metcr
and
power stwsor
combination can
bt> siihstitiitid ,jbr fhc .sensor modrik. Thi' Miwsiiring Rcwivcr can thcw bc Icji
in
t h
c j r q i
i c w y
mcw r
urcwtcv
I
/
mode.
1.
Connect the sensor module to the Measuring Receiver's SENSOR and INPUT connectors.
2.
On
the
Measuring Receiver, press the blue key then press INSTR PRESET (the AUTOMATIC
OPERATION key) to preset the instrument.
3. Zero and calibrate the sensor module using the RF power calibrator in the Measuring Receiver.
Set LOG/LIN to read in dBm.
4.
Connect the sensor module's input directly to A19J3 (LO OUT), or for Option 003, the rear-
panel LO
OUTPUT
connector.
5.
On the Measuring Receiver, press FREQ. Key in 650 MHz to set the LO to the bottom of its
doubler band.
6. Step the LO frequency up in 50 000 kHt steps. (Key in 50 000
fi
kHz for the first step, then
fi
kHz thereafter.)
For
each step, press FREQ to tune the
LO,
then press RF POWER and note
the power reading. Do this until Error 20 or Error 15 is displayed. (The LO has reached the top
of its range or the frequency is beyond the range of the caibration factors of the sensor module.)
The power readings should be between +1.4 and +3.0 dBm. If the power readings are within
range, continue with step 7. If the power readings are out of range, change the components o n
A19 according to the following guidelines.
a. To increase the power throughout the entire doiibler band. decrease the value of A19R63.
(IJse values
nittiin
the range 38.
I to I 100.)
5-10
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