Gauging Connectors

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Because coaxial connector mechanical tolerances can be very precise, even a perfectly clean connector can cause trouble if out of mechanical specification.

Important - Connector Gauge Accuracy

Hand-held connector gauges, such as the one shown below, are only capable of performing coarse measurements on mmWave connectors. This is due to the uncertainties of the measurement versus the extremely precise mechanical tolerances of the connectors. Only special gauging processes performed in a calibration lab can accurately verify the mechanical characteristics of these devices.

Therefore, before making pin depth measurements, it is necessary to know the uncertainty of your gauge and the specifications of the connector you are gauging. These values are supplied in Keysight Cal Kit manuals. You may not be able to definitively determine if your connector is within specifications - only to identify gross failures.

When to Gauge Coaxial Connectors

Gauge a connector:

Note: Gauge 2.4 mm, 3.5 mm, and SMA connectors more often than other connectors because the center pins can pull out during disconnect.

Typical Connector Gauge

RECESSION

PROTRUSION

 

Pin Depth Recession and Protrusion

1. Recession of female contact

2. Recession of male pin shoulder

Keysight Gauge Part Numbers

Each connector has a specific gauge part number for measurement of both the male and the female connector. Each gauge uses a special precision gauge master to zero the gauge.

Type

Male

Female

APC 7 mm

85050-80012

3.5 mm

11752-60106

11752-60105

2.4mm

11752-60108

11752-60107

2.4mm short (for airlines)

85056-60020

N/A

1.85 mm

11752-60108

11752-60107

 

Gauging Procedure

  1. Wear a grounded wrist strap having a 1 MW series resistor.

  2. Select the proper gauge for your connector.

  3. Inspect and clean gauge, gauge master, and device to be gauged.

  4. Zero the connector gauge.

    1. While holding gauge by the barrel, carefully connect gauge master to gauge. Finger-tighten connector nut only.

    2. Use proper torque wrench to make final connection. If needed, use additional wrench to prevent the gauge master from turning. Gently tap the barrel to settle the gauge.

    3. The gauge pointer should line up exactly with the zero mark on gauge. If not, adjust "zero set" knob until gauge pointer reads zero. On gauges having a dial lock screw and a movable dial, loosen the dial lock screw and move the dial until the gauge pointer reads zero. Gauges should be zeroed before each set of measurements to make sure zero setting has not changed.

    4. Remove gauge master.

  5. Gauge the device connector.

    1. While holding gauge by the barrel, carefully connect DUT to gauge. Finger-tighten connector nut only.

    2. Use proper torque wrench to make final connection and, if needed, use additional wrench to prevent DUT body from turning. Gently tap the barrel to settle the gauge.

    3. Read the gauge indicator dial for recession or protrusion and compare reading with device specifications.

Caution: If the gauge indicates excessive protrusion or recession, the connector should be disposed of or repaired.

  1. For maximum accuracy, measure the device a minimum of three times and take an average of the readings. After each measurement, rotate the gauge a quarter-turn to reduce measurement variations.

  2. If there is doubt about measurement accuracy, be sure the temperatures of the parts have stabilized. Then perform the cleaning, zeroing, and measuring procedure again.