HP 5340A Operating And Service Manual page 113

Frequency counter
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Model 5340A
Maintenance and Service
11. A22R52 ADJUSTMENT
This adjustment is set and sealed at the factory for optimal sensitivity and should
be adjusted only if A22U9 is replaced or if the 5340A will not meet the sensitivity
test in step 3.
a.
Install the board on a n extender board. Disconnect the cable connected to A22J1. Remove A17A1
(05340-60038).
Connect a suitable BNC to SMB push-on adaptor (such as Sealectro 51-077-6801 HP P/N 1250-1236)
b.
to the A22J1 direct count input on A22.
C .
Install a BNC T to the output BNC of a 608 generator.
d.
Using a BNC to BNC cable, carefully connect the 608 to the adaptor on A22J1.
e.
Connect the BNC end of a BNC to alligator cable to the T on the 608. Connect the shield (black) alligator
clip to the positive terminal of a 0-2OV variable power supply.
f.
Connect one end of a 1K ohm 1/4 watt resistor to the negative terminal of the power supply.
Connect the center conductor (red) alligator clip to the other end of the resistor.
h.
Adjust the power supply to 10 volts and set the 608 to 300 MHz at -100 dBm (2.2 microvolts rms).
Set A22R52 to center of adjustment.
1 .
Set the 5340A RANGE switch to 10 Hz to 18 GHz and measure voltage across A22R30 using DVM.
Adjust power supply until DMV reads 0
k.
Set 608 to 12 MHz a t -10 dBm (70 mV rms) and adjust A22R52 for a stable reading on the 5340A display.
1.
Continue to decrease the 608 signal amplitude and adjust A22R52 for maximum sensitivity.
Repeat test using 110 MHz and 250 MHz signals.
n.
Disconnect test set-up and again perform the 50Q Direct Count Adjustment (step
5-12
Figure 5-2. Adjustement Procedures (Continued)
NOTE
2 mV.
3).

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