Help Identifying Connector

[mfn002]

I recently acquired a VHF-AM aircraft antenna. The RF connector looks like a BNC connector, but is slightly larger. Can anyone identify this?

Sent from my iPhone using Tapatalk

 

[dcr_inc]

From The BNC Connector WIKI...

"Types
BNC connectors are most commonly made in 50 and 75 ohm versions, matched for use with cables of the same characteristic impedance. The 75 ohm types can sometimes be recognized by the reduced or absent dielectric in the mating ends but this is by no means reliable. There was a proposal in the early 1970s for the dielectric material to be coloured red in 75 ohm connectors, and while this is occasionally implemented, it did not become standard. The 75 ohm connector is dimensionally slightly different from the 50 ohm variant, but the two nevertheless can be made to mate. The 50 ohm connectors are typically specified for use at frequencies up to 4 GHz and the 75 ohm version up to 2 GHz. A 95 ohm variant is used within the aerospace sector, but rarely elsewhere. It is used with the 95 ohm video connections for glass cockpit displays on some aircraft."

It doesn't say where you can find a "75 Ohm" BNC though..

 

[mfn002]

That sort of helps, but as I said, it’s slightly larger than a standard BNC male connector. I would like to know what type it is so I can obtain some sort of adapter to make it useable.


I can somewhat recall running into one of these on something several years ago, and from what I recall it wasn't called a BNC connector.

 

[prcguy]

That is a 50 ohm type C connector. You can usually get adapters to type N, BNC and others surplus on Epay.

 

[mfn002]

That is a 50 ohm type C connector.

THANKS!!! Problem solved. A three-pack of C-type to standard BNC connector adapters have just been purchased.

Now my next question is why they would use something like that.

 

[AK9R]

The Wikipedia article for the C connector has a comparison photo between a C and a BNC. https://en.wikipedia.org/wiki/C_connector

Now my next question is why they would use something like that.

Some folks like bayonet connectors rather than threaded connectors. Some folks look at a BNC connector and erroneously assume that it can't handle much RF power. The C, N, and BNC connectors are much more water resistant than a PL259 connector.

 

[majoco]

Bayonet and screw "C"'s were quite commonly used with the thicker RG8 coax cable and even with the solid dielectric/solid copper shield cable - the number escapes me at the moment but I must have made off hundreds of those connectors with the "long back" reinforcement back in the late 60's and 70's installing Instrument Landing Systems.

 

[majoco]

Wait a second....are you sure about that antenna? Most of the VHF communications antennas used BNC connectors. Judging by the bayonet "C" connector and the size of the antenna backplate I'm inclined to think that you might have a DME/TCAS antenna there - 1000MHz not 125MHZ. Give us a pic of the other side - is it just a little blade about 2 inches square with a sloping front to it? Looks like this....