Antenna plug capacitor

[zed2]

When removing the antenna cable from the back of the radio, the male plug broke.  The plug appears to have a capacitor with the natation “180PF +-10% 50V”.

What purpose does this capacitor serve?

Thanks,

Keith

Edited September 7, 2022 by zed2

[SteveJ]

Read this: https://www.frostburg.edu/personal/latta/ee/twinplex/schematic/twinplexschematic.html

Also here: https://maker.pro/forums/threads/car-radio-antenna-has-an-inline-85mfd-capacitor-why.102193/

Edited September 6, 2022 by SteveJ

[zed2]

So is it more common for the capacitor to be mounted in the plug or on the radio circuit board?

[SteveJ]

I wouldn't know. I've never had to design such a circuit.

[Captain Obvious]

4 hours ago, zed2 said:

What purpose does this capacitor serve?

I'm no radio expert, but I believe the purpose of that capacitor is a filter to only allow signals through in the range that the radio cares about. It also blocks any DC voltages, so you won't ever be able to shock yourself by grabbing the antenna or some other strange fault like that.

You could put that filter either in the plug (as they have), or inside the radio case, but the sooner you get rid of the stuff you don't want (noise), the better.

That's my take.