FME Coaxial Cable Connectors
Posted: Sun Dec 20, 2015 7:55 am
Recreational boaters may not be familiar with the FME connector. The FME acronym comes from "For Mobile Equipment." The FME family is a newer family of coaxial cable connectors often used with RG-58-type 50-Ohm transmission lines or other smaller diameter lines, as well as RG-8X cable. The FME connector has been designed to have a very small diameter in order to allow a coaxial cable with a pre-installed FME connector to be snaked through tight passages during installation. FME connectors are used by MORAD in their accessory transmission lines for their antennas.
The FME connector is similar in size to the Mini-UHF connector. In recreational boating, the Mini-UHF connector has come to be used by at least one antenna manufacturer (Digital Antennas). They pre-install a Mini-UHF female (or jack) connector on the transmission line of some of their antennas and supply an appropriate adapter to convert to a standard size UHF plug for connection to equipment. Having the coax include a pre-installed connector has been seen as a significant benefit by many boaters, for whom otherwise having to install a connector would be a burden.
The FME connector can be employed in the same manner. A possible advantage of the FME connector over the Mini-UHF connector is the availability of the FME connector from many sources, along with the necessary adapter, and perhaps a slight advantage in a smaller overall diameter.
Using AMPHENOL parts, and MOUSER as the distributor, FME connectors and adapters are easily sourced. The cable-end connector is Amphenol part number 192102, FME STRAIGHT CABLE JACK. Mouser has these in stock at $3.80 as their part number 523-192102. The hex-shaped retaining nut is only 0.315-inch (8-mm) across the flats. The overall length of the connector is about 1.1-inch. This connector is for RG-58C/U or similar cable.
The adapter is Amphenol part number 192110, RF Adapter, Between Series, FME PLUG to UHF PLUG. Mouser has these in stock at $8.62 as their part number 523-192110.
I like the design of this adapter. It has flats on the body of the connector so it can be held with a small wrench. The FME cable end connector can then be tightened snugly into the adapter using another wrench (on the hex nut of the FME connector).
The FME cable-end connectors are all designed for installation with crimp tools. The recommended hexagonal crimp diameters are 0.068-inch and 0.213-inch. The recommended crimp tool is Amphenol part number 47-10070. Mouser stocks this tool as their part number 523-47-10070 at about $115.
All three element of this connector system, the cable end connector, the FME to UHF adapter, and the Hex Sizes: .068, .100, .213, .256, .324 crimp tool, are also available from alternate suppliers such as SHOWMECABLES.COM in Missouri (to which hyperlinks are given in the preceding text). Again, the most expensive element is the crimp tool, but at about half the price of the Amphenol-brand, the $43 no-brand crimp tool may be a tolerable expense for some boaters.
According to the Amphenol specifications, their FME connector can be used with the following cable types:
--RG-58, RG-58A, RG-58C
--RG-141
--RG-303
--LMR195, and
--Belden 7806A.
The connector is a 50-Ohm impedance connector and is typically used in applications up to 200-MHz, although in some cases used as high as 2-GHz.
The Amphenol FME series is also available for RG-8X or Time LMR240 cable, which has a larger diameter. The Amphenol part number is 192116. Mouser sells these for $13.16. The alternate supplier, SHOWMECABLES.COM has similar connectors for much less, only $5.09.
[NOTE APRIL 2023: I just spent about an hour fixing all the dead links in this article and adjusting the prices to the April 2023 prices shown at the various vendors. The cost of some of these small connectors has just about doubled since this article was initially published.]
The FME connector is similar in size to the Mini-UHF connector. In recreational boating, the Mini-UHF connector has come to be used by at least one antenna manufacturer (Digital Antennas). They pre-install a Mini-UHF female (or jack) connector on the transmission line of some of their antennas and supply an appropriate adapter to convert to a standard size UHF plug for connection to equipment. Having the coax include a pre-installed connector has been seen as a significant benefit by many boaters, for whom otherwise having to install a connector would be a burden.
The FME connector can be employed in the same manner. A possible advantage of the FME connector over the Mini-UHF connector is the availability of the FME connector from many sources, along with the necessary adapter, and perhaps a slight advantage in a smaller overall diameter.
Using AMPHENOL parts, and MOUSER as the distributor, FME connectors and adapters are easily sourced. The cable-end connector is Amphenol part number 192102, FME STRAIGHT CABLE JACK. Mouser has these in stock at $3.80 as their part number 523-192102. The hex-shaped retaining nut is only 0.315-inch (8-mm) across the flats. The overall length of the connector is about 1.1-inch. This connector is for RG-58C/U or similar cable.
The adapter is Amphenol part number 192110, RF Adapter, Between Series, FME PLUG to UHF PLUG. Mouser has these in stock at $8.62 as their part number 523-192110.
I like the design of this adapter. It has flats on the body of the connector so it can be held with a small wrench. The FME cable end connector can then be tightened snugly into the adapter using another wrench (on the hex nut of the FME connector).
The FME cable-end connectors are all designed for installation with crimp tools. The recommended hexagonal crimp diameters are 0.068-inch and 0.213-inch. The recommended crimp tool is Amphenol part number 47-10070. Mouser stocks this tool as their part number 523-47-10070 at about $115.
All three element of this connector system, the cable end connector, the FME to UHF adapter, and the Hex Sizes: .068, .100, .213, .256, .324 crimp tool, are also available from alternate suppliers such as SHOWMECABLES.COM in Missouri (to which hyperlinks are given in the preceding text). Again, the most expensive element is the crimp tool, but at about half the price of the Amphenol-brand, the $43 no-brand crimp tool may be a tolerable expense for some boaters.
According to the Amphenol specifications, their FME connector can be used with the following cable types:
--RG-58, RG-58A, RG-58C
--RG-141
--RG-303
--LMR195, and
--Belden 7806A.
The connector is a 50-Ohm impedance connector and is typically used in applications up to 200-MHz, although in some cases used as high as 2-GHz.
The Amphenol FME series is also available for RG-8X or Time LMR240 cable, which has a larger diameter. The Amphenol part number is 192116. Mouser sells these for $13.16. The alternate supplier, SHOWMECABLES.COM has similar connectors for much less, only $5.09.
[NOTE APRIL 2023: I just spent about an hour fixing all the dead links in this article and adjusting the prices to the April 2023 prices shown at the various vendors. The cost of some of these small connectors has just about doubled since this article was initially published.]