B&K Precision 1856D - Manual - Manual (Page 16)

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pushed in, the signal at input A is routed through a low pass filter (-3 dB
point at approximately 100 KHz) before it is applied to the counter. This
helps eliminate counting errors in low frequency measurements by
minimizing effects of high frequency noise that may accompany the signal.
h. When making measurements near the lower cut-off frequency of input A
(10 Hz or less), use DC coupling (Push in the DC COUPLING switch).
B. INPUT C (80 MHz to 3.5 GHz)
CAUTION
THE MAXIMUM INPUT TO THIS INPUT IS 3 Vrms OVER THE INPUT
FREQUENCY RANGE. THE “X 10 ATTENUATOR” DOES NOT APPLY.
a. Apply the signal to be measured at input C.
b. Set the FUNCTION indicator to FREQ. C
c. Select the resolution using the GATE TIME selector switch.
d. The frequency is indicated on the display. The gate indicator is lit while the
measurement is in progress, and the display is updated at the end of each
measurement interval.
e. Engaging the HOLD switch “freezes” the display at the existing reading,
When HOLD is released, the display is updated and resumes counting.
f. The ATTENUATOR, LPF, and COUPLING switches have no effect with
input C.
3-4. Period Measurements
a. Apply the signal to be measured at input A.
b. Select the resolution using the GATE TIME selector switch.
c. The period is indicated on the display. The gate indicator is lit while the
measurement is in progress.
d. The ATTENUATOR, LPF, and COUPLING switches operate the same as
they do in the frequency measurements modes.