APC-7 connector
 Recessed threads (left), Protruding threads (right) | |||
| Type | RF coaxial connector | ||
|---|---|---|---|
| Production history | |||
| Manufacturer | Originally Amphenol, then Hewlett-Packard, then others | ||
| General specifications | |||
| Diameter | 7 mm (0.28 in) | ||
| Passband | 0-18 GHz | ||
The APC-7 connector (all referred to as a 7 mm connector) is a precision coaxial connector that was used on laboratory microwave test equipment for frequencies up to 18 GHz. APC-7 connectors were advantageous because they have a low-reflection coefficient, make repeatable coaxial connections, and are genderless. (Hewlett-Packard 1979, p. 90) The connectors are expensive, so they are seldom used outside the laboratory where their cost can be justified by their accuracy and convenience. Due to their high cost, their 18 GHz frequency limitation, and new laboratory practices,[1] the connectors are now uncommon. Modern low frequency microwave equipment often uses the less expensive 3.5 mm (26.5 GHz) connector. Higher frequency equipment must use higher performance connectors such as the 2.92 mm (40 GHz), 2.4 mm (50 GHz), or 1.0 mm (110 GHz) connectors.[2]
Features
APC-7 connector pairs have several desirable features:
- The connectors are genderless. This avoids some awkward adapters or duplication of laboratory standards. With a gendered connector, a laboratory might need a precision male load and a precision female load. With a genderless 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 and low voltage standing wave ratio (VSWR). The low reflection coefficient means better measurement accuracy. The typical VSWR is 1.025:1 at 18 GHz. (Hewlett-Packard 1979, p. 90)
- The mated pair makes a repeatable connection. A pair has a repeatable reflection coefficent to ±0.001. (Hewlett-Packard 1979, p. 90) Consequently, laboratory measurements have reduced uncertainty.
Adapters
The APC-7 connector required adapters to change from the connectors used in the laboratory to those used on everyday products. These adapters are expensive precision devices. For example, an APC-7 to type N (f) cost $105 in 1979. (Hewlett-Packard 1979, p. 87)
History
"APC" stands for Amphenol Precision Connector and "-7" for 7 millimetres.[3] Hewlett-Packard started developing the connector in the mid-1960s. Amphenol improved the design and manufactured the connector. (Hewlett-Packard 1979, p. 90) Companies will often change the first letter of the acronym to match theirs, for example, RPC-7 from Rosenberger Micro-Coax. To address this, the abbreviation GPC-7 was designated to mean "General Precision Connector-7".[citation needed]
LPC-7 (Laboratory Precision Connector-7) refers to inner conductors with only air dielectrics.[citation needed] 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.[citation needed]
References
- ^ Connections at the instrument front panel don't need to be repeatable because those connections remain mated during tests. Modern network analyzers focus on the reference plane near the device under test and have features such as automated calibration, adapter removal, and models for calibration references. The advantages of the APC-7 connector have been diminished.
- ^ http://www.microwaves101.com/encyclopedia/connectors.cfm
- ^ http://www.amphenolrf.com/products/precision.asp?N=0&sid=4A4D4A002301E17F&
- Hewlett-Packard (1979), Coaxial & Waveguide Catalog and Microwave Measurement Handbook, vol. 5952-8207D, Palo Alto, CA: Hewlett-Packard