User`s guide

53220A/53230A User’s Guide 125

53220A/53230A Input Signal Conditioning 4

Setting the Probe Factor

For better access to test points on the device under test (DUT), Agilent recom-

mends its N2870A, N2873A, and N2874A Passive Probes for use with the

53220A/ 53230A counter. The 35 MHz (BW) N2870A 1:1 probe and the

500 MHz N2873A and 1.5 GHz N2874A 10:1 probes are popular accessories

commonly used with Agilent oscilloscopes.

When using probes with the counter, specifying a probe factor references and

displays threshold levels and p-p levels relative to actual levels on the DUT,

rather than to the level at the channel input. The probe factor is set with the

command:

INPut[{1|2}]:PROBe {<factor>|MINimum|MAXimum|DEFault}

INPut[{1|2}]:PROBe? [{MINimum|MAXimum|DEFault}]

(query form)

Probe factor settings are 1 for a 1:1 probe (N2870A), and 10 for a 10:1 probe

(N2873A or N2874A). When set to 1, the counter ranges are 5V and 50V. When

set to 10, the counter ranges are 50V and 500V.

Probe Input Compatibility The input compatibility of the N2870A and N2873A

probes is 1 M

Ω respectively. The compatibility of the N2874A is 50Ω . Each is

compatible with the counter’s 20 pF input capacitance. When using a probe,

the counter input impedance should be set accordingly (1M

Ω, 50Ω).

CONFigure and MEASure do not change the probe factor setting. Following a

reset (*RST) or an instrument preset (SYSTem:PRESet or Preset key), the

probe factor is set to 1.