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 (also referred to as a 7 mm connector) is a precision coaxial connector used on laboratory microwave test equipment for frequencies up to 18 GHz. APC-7 connectors are advantageous because they have a low reflection coefficient, make repeatable coaxial connections, and are genderless.[1] 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,[note 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), 1.85 mm (67 GHz), or 1.0 mm (110 GHz) connectors.[2]


APC-7 connector pairs have several desirable features:


APC-7 connectors require 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.[3] Such adapters bought new today (as of July 2012) can cost as much as $294.[4]


"APC" stands for Amphenol Precision Connector and "-7" for 7 millimetres.[5] Hewlett-Packard started developing the connector in the mid-1960s. Amphenol improved the design and manufactured the connector.[1]


  1. ^ 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.


  1. ^ a b c d Coaxial & Waveguide Catalog and Microwave Measurement Handbook. Palo Alto, CA: Hewlett-Packard. 1979. p. 90. 5952-8207D.
  2. ^ "Microwave Coaxial Connectors". www.microwaves101.com. 2009-05-03. Archived from the original on 2009-05-12. Retrieved 2010-04-05.
  3. ^ Coaxial & Waveguide Catalog and Microwave Measurement Handbook. Palo Alto, CA: Hewlett-Packard. 1979. p. 87. 5952-8207D.
  4. ^ "11525A Adapter, APC-7 to Type-N (m), DC to 18 GHz". Keysight. Retrieved 2022-02-24.
  5. ^ "Capabilities - Custom RF Products and Engineered Solutions - Amphenol RF". www.amphenolrf.com. Archived from the original on 2019-05-02.