Fluke 85RF Operating Manual

85RF II

High Frequency Probe

Instruction Sheet

Introduction

The 85RF II High Frequency Probe (the Probe) transforms a
dc voltmeter into a high frequency (100 kHz to 500 MHz) ac
voltmeter. Conversion from ac to dc is done on a one-to-one
basis and includes a range of 0.25 V rms to 30 V rms. The
Probe’s dc output is calibrated to be equal to the rms value
of a sine wave input.

Safety

Symbol Description

W
X

~

To prevent possible electrical shock, fire, or personal
injury:

• Examine the case before you use the Product.

Look for cracks or missing plastic. Carefully
look at the insulation around the terminals.

• Limit operation to the specified measurement

category, voltage, or amperage ratings.

• Do not touch voltages >30 V ac rms, 42 V ac

peak, or 60 V dc.

• Do not use the Product around explosive gas,

vapor, or in damp or wet environments.

• Do not use and disable the Product if it is

damaged.

• Use the Product only as specified, or the

protections supplied by the Product can be
compromised.

• Do not exceed the Measurement Category (CAT)

rating of the lowest rated individual component
of a Product, Probe, or accessory.

• Keep fingers behind the finger guards on the

Probes.

• Do not connect directly to mains.

See Instruction Sheet.

Hazardous voltage.

Do not dispose of this product as
unsorted municipal waste. Go to Fluke’s
website for recycling information.

WXWarning

®

PN 4096837
September 2011, Rev. 1, 12/11

©2011 Fluke Corporation, Printed in the U.S.A. All product names are
trademarks of their respective companies. Specifications are subject to change
without notice.

Specifications

AC to DC ratio: 1:1

Ratio accuracy: (at 25 MHz and loaded with 10 Me )

Above 0.5V: ± 0.5 dB
Below 0.5V: ± 1.0 dB
Add ±0.2 dB in RF fields of 1 V/m to 3 V/m

Frequency response: (Relative to 25 MHz)

100 kHz to 80 MHz ±0.5 dB
*80 MHz to 200 MHz ±2.0 dB
*200 MHz to 300 MHz ±3.5 dB
*300 MHz to 400 MHz ±4.5 dB
*400 MHz to 500 MHz ±5.5 dB
*Referred to high and low inputs at Probe tip.

Extended frequency response:

Useful for relative measurements from
20 kHz to 700 MHz.

Response:

Responds to the peak value of an input and is calibrated
to read rms value of a sine wave.

Voltage range: 0.25 V rms to 30V rms

Maximum input voltage: 30 V rms, 200 V dc

Input capacitance: Approximately 9 pF

Temperature range:

Operating: +10 °C to +35 °C
Storage: -40 °C to +75 °C

Humidity: <90 % R.H.

Output connector:

Fits standard 0.75 inch dual banana connectors

Accessory:

BNC to Probe Adapter, P/N 574756

Pollution degree: 2

Operating altitude: 3000 m

Warranty: 1 year

Voltmeter Compatibility

The 85RF II can be used with a dc voltmeter that has an
input resistance of 10 Me, ±10 %. Voltmeters with higher
input resistances are usable if an external shunt is put
across the input terminals. The shunt value is set to
decrease the input resistance to 10 Me.