Frequency	DC - ~300 MHz (best below 200 MHz); 50 ohm nominal
Bands	HF/VHF (per ~300 MHz limit)
Power	The standard ham coax connector. Not a constant-impedance design (a ~35 ohm bump in the SO-239), so loss rises above ~200 MHz; fine for HF and 2 m.
Modes	n/a

Connectors

plug	PL-259 male (UHF)
jack	SO-239 female (UHF)
thread	5/8 in-24 tpi shell
power req	None (passive connector).

The ubiquitous amateur coax connector (PL-259 plug / SO-239 jack) 5/8-24 threaded shell; ~0.156 in center pin 50 ohm nominal, but non-constant impedance (bump in the SO-239) Usable to ~300 MHz; best kept below ~200 MHz Solder or crimp versions for RG-8/213/58/8X etc. High power handling at HF; cheap and universal

Strengths

Universal on HF/VHF ham gear; rugged and cheap; high power handling; easy to install (solder or crimp).

Weaknesses

Impedance discontinuity raises loss above ~200 MHz; not weatherproof (needs sealing); poor at UHF/microwave.

Verdict

The default ham radio connector - the UHF PL-259/SO-239 is fine and cheap through 2 m, but step up to Type N for 70 cm and above.

The UHF connector - PL-259 plug and SO-239 jack - is the ubiquitous amateur coax fitting: a 5/8-24 threaded shell, 50 ohm nominal but with an impedance bump in the SO-239 that raises loss above ~200 MHz. It is cheap, rugged and fine for HF and 2 m.

For higher bands use the Type N connector; install it on RG-213/U.

PL-259 / SO-239 (UHF Connector)