Filter
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Adjustment Procedures
5-20
2715 Spectrum Analyzer Service Manual
l. When normalizations are complete, select the following settings on the
Spectrum Analyzer:
FREQUENCY 100 MHz
REF LEVEL --20 dBm
SPAN/DIV 100 kHz
m. Connect a 100,000,000.0 Hz signal to the RF INPUT. Set the controls
for a full screen display.
n. Initiate reference frequency normalizations by pressing
UTIL55112W.
o. After normalizations are completed, press any menu button to return to
the spectral display.
Use this procedure to adjust the 110 MHz Bandpass F ilter on the RF Mother
board.
1. Recall factory default power up settings by pressing UTlL1 1.
2. Select the following settings on the Spectrum Analyzer:
FREQUENCY 100 MHz
REFERENCE LEVEL --30 dBm
SPAN/DIV 2 MHz
VERT SCALE 10 dB/div
3. Connect a 100 MHz/--30 dBm signal to the RF INPUT. Center the display by
pressing CTR-MEAS TRKG.
4. Enable bandwidth mode by pressing APPL 9 0, entering --6 dB, and pressing
BKSP 0.
5. Change the resolution bandwidth to 5 MHz. (The bandwidth readout will
continuously update as the adjustments are made.)
6. Starting with the capacitor towards the top of the instrument, adjust the five
capacitors for highest amplitude, best filter shape of the 5 MHz pass band
(4 to 6 MHz), and centering. See Figure 5--4 on Page 5--16 for the locations
of the five capacitors on the RF Mother board (FILTER ADJUSTMENTS).
If necessary, adjust C280 and C392 (See Figure 5--6 on Page 5--21) on the
Log board for amplitude and filter shape.
7. Decrease the reference level by one step and check that the filter shape is not
severely distorted.
5 MHz Resolution
Bandwidth Adjustment