The APC-7 connector
Precision Connector) is a precision sexless
, 7 mm
, coaxial connector that was used on laboratory microwave test equipment up to 18 GHz
. The connector is not suitable for modern laboratory equipment that works above 18 GHz, so the connectors are not as common as they were.
The connectors are expensive, so they are seldom used outside the laboratory.
APC-7 connectors are used on microwave test equipment because low-reflection coefficient and repeatable coaxial connections are required. Furthermore, cost is not a central concern for test equipment: accuracy is.
An APC-7 connector pair has several desirable features.
- The connectors are sexless. Sexless connectors avoid some awkward adapters or duplication of laboratory standards. With a sexed connector, a laboratory might need a precision male load and a precision female load. With a sexless connector, only one load is required.
- The connectors have a well defined reference plane. Consequently, the connectors simplify some measurements.
- The mated pair of APC-7 connectors has a low reflection coefficient / low VSWR. The low reflection coefficient means better measurement accuracy. The maximum VSWR is 1.04:1 at 18 GHz.
- The mated pair makes a repeatable connection. A pair has a repeatable reflection coefficent to ±0.001. Consequently, laboratory measurements will be repeatable.
The features of the APC-7 connector come at a price — adapters are required to change from the laboratory world to the connectors that are used on everyday products. These adapters are precision devices and are expensive.
Adapters between APC-7 and other common RF connectors (e.g. N, SMA, TNC) are available from various vendors.
Origin of the name
APC-7 stands for Amphenol Precision Connector – 7 mm. Hewlett-Packard started developing the connector in the mid-1960's. Amphenol improved the design and started manufacturing the connector.
The connector is sometimes referred to a just a 7 mm connector. (Amphenol also developed the smaller APC-3.5 connector that is an improvement on the SMA connector.)
Companies will commonly change the first letter of the acronym to match theirs. So you sometimes see APC-7 from Maury Microwave or Agilent Technologies or RPC-7 from Rosenberger Micro-Coax.
For this reason the acronymn GPC-7 was introduced. This is short for General Precision Connector-7.
LPC-7 (Laboratory Precision Connector-7) refers to inner conductors with only air dielectrics. This means that LPC-7 can only refer to unsupported air lines.
As GPC-7 started to be used for lower grades of the same type, a catch all of PC-7 (Precision Connector-7) is now often used.