BBK Electronics BK Precision 1856D Manuale Utente

5-2. Attenuator Probes

When measuring signals at input A that will exceed its maximum input voltage

level (See FIG. 1), a 10:1 attenuating probe such as an oscilloscope probe should

be used.

NOTE

DO NOT USE A 10:1 PROBE WITH THE INPUT C. THESE PROBES ARE

DESIGNED WITH A 10:1 ATTENUATION FOR AN INSTRUMENT WITH AN

INPUT RESISTANCE OF 1 M

Ω. THE 50 Ω TERMINATION OF INPUT C WOULD

RESULT IN UNACCEPTABLY HIGH ATTENUATION.

5-3. Line Frequency Measurements

When making line frequency measurements, use of the LOW PASS FILTER, the

ATTENUATOR, and/or the 10:1 probe is recommended.

WARNING

USE CAUTION WHEN MEASURING THE LINE FREQUENCY OF AN AC

OUTLET. USE THE PROBE TIP ONLY, AND MEASURE BOTH SIDES OF THE

LINE. THE NEUTRAL SIDE WILL GIVE A ZERO READING AND THE HOT SIDE

WILL PROVIDE THE DESIRED MEASUREMENT. DO NOT USE THE "GROUND"

LEAD OF THE PROBE. REMEMBER THAT THE CHASSIS OF THE COUNTER

AND THE “GROUND” LEAD OF THE PROBE ARE ALREADY AT EARTH

GROUND (VIA THE 3-WIRE POWER CORD OF THE INSTRUMENT). TOUCHING

THE “GROUND" LEAD TO THE 'HOT" SIDE OF THE LINE WOULD PLACE A

DIRECT SHORT ON THE POWER LINE THROUGH THE PROBE CABLE,

RESULTING IN A BIG SPARK, DAMAGE TO THE PROBE CABLE, AND

POSSIBLE INJURY TO THE USER.