Feed through caps are not a cap from input to output, but from center conductor to ground.
Think of them as a coaxial bypass cap. So, for a DC feed through you would use a value that you would typically use as a bypass cap. When used to feed RF out, you want to pay closer attention to the value because, in essence, it is a low pass filter.
They come in many styles including threaded and solder in type.
Feed through capacitors were originally designed for DC power line in an RF module or system. It passed through the DC (and low frequency signals) but blocks the RF energy. In practical use, the feed through capacitors are fitted to the metal case of the RF module where the wires enter the system. They let the signal pass through but will stop the RF from escaping from the device through that hole to the outside wiring.
It’s mainly a kind of ceramic capacitor. Temperature characteristics of my company is X7R, NPO, SL, KL, Y5V, Y5U and Y5P. Installation way: Through hole.
