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I intend to replace an antenna cable of my FM receiver. Now it has a flat 300 ohms that need to be replaced. I want to put a 75 ohms coaxial cable, because the receiver also has an input of 75 ohms.
What is the best: 75 ohms coaxial cable or flat 300 ohms?
I intend to replace an antenna cable of my FM receiver. Now it has a flat 300 ohms that need to be replaced. I want to put a 75 ohms coaxial cable, because the receiver also has an input of 75 ohms.
What is the best: 75 ohms coaxial cable or flat 300 ohms?
Personally I would say coaxial is best, because it's screened - however, it doesn't really matter as long as both ends are terminated correctly with the correct impedance.
If you amp is 75 ohm, and you cable is 75 ohm, BUT your aerial is 300 ohm, you need to add a balun (BALanced/UNbalance transformer) at the aerial, to convert from 300 to 75 ohms.
Likewise, if you use 300 ohm feeder from your 300 ohm aerial, you need to add a balun at the receiver end.
Mixing the impedances up makes a considerable lose of signal!.
I also think that 75 ohm coax is better simply because you can install it more cleanly in exposed areas. With the flat ribbon cable anytime you want to make a bend in the same plane as the flat of the cable you have to curl it or fold it or such and it looks messy.
While coax might be preferred because of sheilding you might find that the 300 ohm twinlead has a lower loss per unit length. On a short run of a few meters there can't be that much difference - at 10 or more meters you might see the difference. Various manufacturers publish loss data. While there are some generally understood loss factors there can be quite a difference between manufacturers of even the same cable type.
As already mentioned, impedance matching is important.
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