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Calibration Tests and Adjustment

Attenuator Adapter Adjustment

Attenuator Adapter Adjustment
The following procedure should be used if it is necessary to adjust an attenuator adapter.
Attenuator adapters have only characteristics; they do not have any specifications. An
adapter will need adjustment only if one or more of the following occurs.
• If an adapter is to be used on a different 1141A probe that it was calibrated with
last.
• If an adapter needs to be optimized to requirements for a special measurement.
• If an adapter is suspected of needing adjustment.
NOTE Attenuator adapters should not be adjusted as part of routine maintenance. The design
necessary to give the high CMRR and high impedance of the attenuators makes
adjustment delicate.
Additionally, because of broadband noise, a spectrum analyzer should be used to verify
adjustment quality.
Each attenuator contains two identical voltage dividers on a ceramic substrate. There
are three adjustments. The low-frequency CMRR adjust the low-frequency balance
between the two voltage dividers. The two high-frequency adjustments are electrically
identical. Each adjusts the high-frequency compensation of one of the voltage dividers.
To meet both pulse response and CMRR characteristics they are adjusted differently.
Briefly, the adjustment procedure is:
aAdjust the positive high-frequency response (+ HF RESP) for the best pulse response
using a 3.5 kHz square wave.
bAdjust the negative high-frequency response (-HF RESP) and Low-frequency CMRR
(LF CMRR) for best CMRR using a 3.5 kHz square wave.
The following equipment is required for this procedure. Procedures are based on the
model or part number recommended.
Equipment Required
Equipment Required Critical Specifications Recommended
Model/Part
Function Generator 3.5 kHz, 3 V to 16 Vp-p 33120A
Oscilloscope 100 MHz at 1 mV/div 54830B
Probe/Power Module No substitute 1141A/1142A
Test Board No substitute 01141-66504
Cable BNC, 50 Ω 9-inch 10502A
Cable BNC, 50 Ω 36-inch 10503A
Alignment tool Flat blade (supplied accessory) 8710-1961/
Sprague-Goodman
part, GTT-5G