I’m new to wireless mics having just bought two Shure ULXP units. I was looking for a rack mount for the antennas when I came across this
ebay listing for dual remote antenna kit In the description the seller says that 75 ohm coax is better for this use. Shure specs 50 ohm cable and connectors. I don’t know a lot about this so I thought I’d ask the experts here.
Does this make sense or is it BS?
The relevant section is below
Ed
“What's the difference between 50 and 75 ohm coaxial cable?
Coaxial cable is comprised of three main components. In the middle of the coaxial cable is what is known as the center conductor. It can be made of either solid or stranded wire and is typically a mix of Aluminum and Copper. Surrounding the center conductor is something called the dielectric. The dielectric acts as a buffer of sorts to keep the center conductor isolated and straight. It usually is comprised of some blend of plastic and/or foam. Finally, on the outside of the dielectric is the coaxial cable’s shield, which is usually a combination of Copper and Aluminum foil and/or wire braid. The shield is then coated by something like PVC to insulate it from the environment.
Now, not all coaxial cable is created equal and that is where the coaxial cable impedance comes into play. It is the coaxial cable’s physical characteristics that will determine its impedance. According to Wikipedia, “The characteristic impedance of the coaxial cable (in Ohms) is determined by the dielectric constant of the inner insulator and the radii of the inner and outer conductors.” The cutaway drawing above is helpful in visualizing these characteristics. With these details in mind, over time, the industry settled on two characteristic coaxial cable impedances for the vast majority of applications (>90%): 50 Ohm and 75 Ohm.
With 50 Ohm Coaxial Cables being the best compromise solution, practically any application that demands high power handling capacity, i.e. 100 watts or more, will use 50 Ohm Coaxial Cable. A good rule of thumb is that any device that functions as a transmitter or transceiver tends to use 50 Ohm Coaxial Cable. This includes devices such as CB/Ham Radios, Broadcast Radio/TV Transmitters, Wi-Fi and Cellular Phone Repeaters and 2-Way Radios (Walkie Talkies).
However, not every case warrants high power handling, so 50 Ohm Coaxial Cable is not appropriate for every application. When the objective is to ensure that the signal gets through the cable in the most efficient way possible, losing very little signal strength in the process, 75 Ohm Coaxial Cable is the way to go. A good rule of thumb is that if the device being connected via coaxial cable is a receiver of some kind, 75 Ohm Coax is ideal. This includes devices such as Satellite and Cable TV Receiver Boxes, High Definition Televisions, AM/FM Radio Receivers and Police Scanners.
This combination of low attenuation and capacitance effectively make 75 Ohm Coaxial Cable the cable of choice for practically all types of digital audio, digital video and data signals. This is why every cable TV company uses 75 Ohm coax for distributing its digital video channels as well as its broadband internet data signals. Direct broadcast satellite dishes and over-the-air HDTV antennas also require 75 Ohm Coaxial Cable to ensure that all of the digital channels transfer down the cable with the lowest loss and distortion possible. “