RG-214/U is a great double shielded coax for most low level repeater applications. I use it in my UHF 70 centimeters repeater from the duplexer to the transmitter. It’s also used on the receive side of the repeater from the duplexer to the bandpass cavity filter, to the preamplifier, to the receiver.
The inner conductor of RG-214/U is made of 7 strands silver plated copper, and is covered by a dielectric made from polyethylene. Inner and outer shielding are both silver plated copper braids. The operating range is from -4 F to +176 F.
The impedance of RG-214/U coax is 50 ohms. It has a velocity factor of 65.9% with a maximum operating frequency of 11 GHz. At 100 feet, RG-214/U has an attenuation (loss) of 2.01 dB on 100 MHz. On 1000 MHz (1 GHz), the attenuation at 100 feet is 7.32 dB.