
Model 8640B
TM 9-4935-601-14-7&P
ADJUSTMENTS
5-31. OUTPUT LEVEL VERNIER AND METER ADJUSTMENT (Cont'd)
PROCEDURE:
1. Connect equipment as shown in Figure 5-1 after setting Signal Generator's controls as follows:
Meter Function .......................................................................................... LEVEL
COUNTER MODE: EXPAND .......................................................................... Off
LOCK.............................................................................................................. Off
Source ........................................................................................................... INT
AM ................................................................................................................OFF
FM ................................................................................................................OFF
RANGE .............................................................................................32 - 64 MHz
FREQUENCY TUNE ................................................................................50 MHz
OUTPUT LEVEL ............................................................................... As specified
RF ON/OFF ....................................................................................................ON
2. Set OUTPUT LEVEL switch one step ccw from full cw; turn OUTPUT LEVEL vernier until the cursor lines up with
the top edge of the white cursor range (i.e., for +13 dBm read on OUTPUT LEVEL switch cursor).
3. Adjust LVL adjustment, A26A4R1, for a +13 dBm reading on power meter. Adjust MET adjustment, A26A4R12,
for a +13 dBm indication on generator's panel meter (+3 dB reading on meter).
4. Set OUTPUT LEVEL switch three steps ccw to -17 dBm. Adjust vernier for a -17 dBm reading on power meter.
5. Disconnect power meter from generator and connect step attenuator, amplifier, and spectrum analyzer to RF
OUTPUT.
6. Set step attenuator to 30 dB. Set spectrum analyzer's center frequency controls to 50 MHz (stabilizer on),
resolution bandwidth to 10 kHz, frequency span per division (scan width to 5 kHz, input attenuation to 0 dB),
display smoothing (video filter) to 100 Hz, and log/linear display switch to 2 dB log. Set the reference level
switch for a -10 dBm reference level at the top graticule line on the display; adjust the reference level vernier to
place the signal to the display's fifth horizontal graticule line.
7. Set generator's OUTPUT LEVEL switch to -47 dBm (i.e., 3 steps ccw). Set analyzer's reference level switch to -
40 dBm and note signal level on display (i.e., the difference between the signal level and the fifth horizontal
graticule line).
8. Set step attenuator to 0 dB; reset analyzer's reference level switch to -10 dBm and adjust analyzer's reference
level vernier for the same signal level noted in step 7.
9. Set generator's OUTPUT LEVEL switch to -67 dBm; set analyzer's reference level switch to -30 dBm and adjust
generator's OUTPUT LEVEL vernier to set signal on analyzer's display to the fifth horizontal graticule line (to the
same place it was set in step 6).
10. Adjust the 10
V adjustment, A1AlR5, for a -67 dBm indication on generator's panel meter (+3 dB reading on
meter).
5-16
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