IEEE STD 287 Precision RF Connectors

Click here to go to our main page on microwave connectors

Click here to go to our Mil Specs for Microwaves page

New for January 2022. Having recently checked out the MIL Spec on coax connectors (MIL-PRF-39012m currently Rev F), you already know that they punted on important things like connector torque settings. Did you know that IEEE has a specification for precision connectors that covers a lot more connectorhood? It's called "IEEE Standard for Precision Coaxial Connectors (DC to 110 GHz)" and was approved 22 March 2007.

If you are fortunate and have an IEEE Explore license, you should download the specification on precision connectors.  Here is the link:

The specification was authored by IEEE Instrumentation and Measurement Society and sponsored by the Connectors in Measurements Committee.  Contributing authors form a virtual who's who of microwave connectors. The document also includes a memorial to Peter Lacy, Bruno Weinschel, Peter Somlo, and Mario Maury, pioneers in the field. Have you done anything in your career that might earn you such an accolade? 

IEEE ST 287 specifies (among other things) upper operating frequency limit, dimensions and tolerances, S-parameter repeatability, disconnect lifetime (if you thought connectors had unlimited connect/disconnect cycles you maybe be in for a rude awakening), shielding effectiveness in decibels, and coupling nut wrench size. It also provides procedures for evaluating connector parameters, the shielding effectiveness setup is quite elaborate.

For now, we will claim "fair use" and repeat the torque spec table and see if the great and powerful IEEE objects.  Easier to ask forgiveness rather than permission, right?

Torque specs

Below is a table of connector torque specs for precision connectors. If you are using a non-precision connector such as SMA or SSMA, consult teh manufacturer's data sheets.

We took the data from IEEE 287, reformatted it a little and added English units of inch-pounds.

Connector type Coupling torque Maximum torque
  Nm in-lb Nm in-lb
14mm 4 35.4 5.4 47.8
7mm 1.5 ± 0.2 13.3 ± 1.8 TBD TBD
N 1.5 ± 0.2 13.3 ± 1.8 TBD TBD
3.5mm 1.5 ± 0.2 13.3 ± 1.8 TBD TBD
2.92mm 0.8 ± 0.2 7.1 ± 1.8 1.8 15.9
2.4mm 0.9 ± 0.2 8 ± 1.8 1.6 14.2
1.85mm 0.9 ± 0.1 8 ± 0.9 1.6 14.2
1mm 0.45 ± 0.05 4 ± 0.4 0.7 6.2

Author : Unknown Editor