RX-488 SERIES

COMPUTER CONTROLLED DECADE RESISTANCE BOX

IET Labs suggests the PRS Series in place of this unit...

The RX-488 series represents a line of decade precision resistor boxes for use wherever a presetable value of resistance is required. IEEE-488 and RS-232 ports allow for remote control of the RX-488. All remote commands are ASCII strings. A front panel keypad and display allow for local control of the RX-488. Connections are made via a pair of binding posts on either the front or the rear of the unit. A third binding post is provided for grounding the case, and a movable shorting link is provided on the front binding posts for connecting the LOW binding post to the case. Use of the front binding posts is recommended for lowest resistance, although using the rear binding posts will typically add less than 0.002 ohms.

The RX-488 typically contains six or seven resistance decades, depending on model number. Each decade has ten switch positions, from zero through nine steps. Resolution and maximum resistance are governed by the chosen model (see model order information box).

The RX-488 box switches have solid-silver contacts at all positions. Brushes are silver alloy to minimize thermally generated EMF. Detents utilize roller bearings to ensure a switch life in excess of one million revolutions. Insulation resistance is greater than one million megohms. Inductance, and capacitance between contacts and to ground, are very low.

MODEL ORDER INFORMATION

The Model Number code is as follows:

1. The digit following the letter R represents the number of decades, to a maximum of seven.

2. The number following the hyphen represents the full scale resistance in ohms.

Typical Models (fewer decades available):

R6-9,999.99ohms-488 for 0.01 ohm/step resolution

R6-99,999.9ohms-488 for 0.1 ohm/step resolution

R6-999,999ohms-488 for 1 ohm/step resolution

R6-9,999,990ohms-488 for 10 ohms/step resolution

R7-99,999.99ohms-488 for 0.01 ohm/step resolution

R7-999,999.9ohms-488 for 0.1 ohm/step resolution

R7-9,999,999ohms-488 for 1 ohm/step resolution

SPECIFICATIONS

ACCURACY

+/-(0.01% of setting + 2 milliohms) at VDC and

23 +/-1 degrees C, referenced to zero resistance

setting. Zero resistance is 0.008 ohms maximum.

CURRENT PER DECADE

0.01 ohm/step: 4 Amps

0.1 ohm/step: 1.6 Amps

1 ohm/step: 700 mA

10 ohms/step: 230 mA

100 ohms/step: 70 mA

1K ohms/step: 23 mA

10K ohms/step: 7 mA

100K ohms/step: 2.3 mA

1 Megohm/step: 0.7 mA

MAXIMUM VOLTAGE

1 KV DC/peak AC, Hi or Lo terminal to case.

PHYSICAL AND POWER

Size: 19" W x 7" H x 12.5" D.

(excluding protruding controls and connectors),

and is designed to mount in a standard 19 inch

relay rack.

Weight: 18 pounds.

Power: 117 VAC +/- 10%, 1 Ampere.

* Specifications subject to change without notice.

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