Amateur Radio Stack Exchange
Amateur Radio Stack Exchange

Questions tagged [coaxial-cable]

Questions about coaxial cables, including different types of cable, connectors, adapters, and other topics.

Coaxial cables have two conductors separated by an insulator. The outer conductor, or the shield, wraps completely around the insulated inner conductor. A coaxial cable is typically utilized to connect a device to an antenna, or to another device.

Questions should relate specifically to the properties of coaxial cables in general or a specific type of coaxial cable. Questions about connectors, including soldering or crimping, or about adapters are also on topic. Finally, questions can be about the use of coaxial cable to create baluns or other matching "circuits".

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How does an SWR meter really work?

For ham radio operators, the SWR meter is a ubiquitous piece of equipment. There are dozens of standalone models on the market and most modern transceivers and antenna tuners have this functionality built in. Any ham with an interest in antennas has…
Glenn W9IQ
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Understanding coax impedance

I keep doing research, and trying to grasp it, but when it comes to RF impedances, and coax, I still have trouble trying to grasp it. So first, I think you have to have a 50 ohm coax for a 50 ohm transmitter to keep the impedances matched. I think I…
Skyler 440
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What should I consider when choosing a coaxial cable?

Given a middling-power rig (up to 100 W) requiring a 50 Ω antenna, a few options for the coaxial cable with a 50 Ω impedance are RG-174 RG-58A/U RG-8 RG-213 Apart from cost, what factors are relevant in deciding which coaxial cable to use?
VU2NHW
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50 Ohm coaxial cable vs 450 Ohm or 600 Ohm ladder or window line?

What are the relative advantages and disadvantages of using 50 Ohm coaxial cable as opposed to 450 Ohm or 600 Ohm ladder or window line?
Timtech
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Is there an optimum Antenna Feedline Length for mobile installations?

I bought a ham radio antenna mounting kit for my car that includes ~16' of coax. One end has a trunk lip NMO antenna mount, the other end has a re-solderable PL-259. I asked the sales person if it is best to shorten the coax after installation to…
BenSwayne
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Is "low loss" cable required for HF?

I use RG-58 for all my HF antennas, since it's light, flexible, convenient, and cheap. And super easy to choke. Whenever I have a problem I just loop a few turns of it on a ferrite core and the problem goes away. Since I operate 100W max and all my…
hjf
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Does Coax Limit the Maximum SWR a Transmitter 'Sees'?

A recent discussion about SWR led to the assertion that a length of coax cable will ultimately limit the SWR to which the transmitter will be exposed. By experimenting with an SWR calculation tool like TLDetails, there appears to be a basis for this…
Glenn W9IQ
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Why are there so many coaxial cable impedances?

Why do we have 50, 75, 62 and 92 Ω coaxial cable, to name a few? Why not just one standardised cable? Is there some technical reason or did Mr. Coax and Mr. Cable have a disagreement, like Mr. Tesla and Mr. Edison?
R Johnson
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How do I design a round or square coaxial transmission line to have a specific impedance?

Certain Hex Beam antennas use a coaxial center support post to send the RF to each antenna section, which is superior, in terms of maintenance, to a post with screw terminals connected by short lengths of coax used in previous designs. I'd like to…
Adam Davis
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How terminate RG8 coaxial cable using PL259 (UHF) - screw - gasket - solder type?

Today I came across a problem in terminating RG8 cable using this PL259 plug. I have never had this type and it arrived in a pile of parts; I have tried to puzzle it together but without positive effect. While googling i came only across crimping…
marc234
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Does a balun need to be made with coax?

The short version My understanding is that one of the main reasons to use a balun with coax is to prevent the outside of the shield from becoming part of your antenna system. If that's the case, won't a design like the one pictured below be…
Dominick Pastore
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Why isn't twisted pair used for feedlines?

My son was asking about some Ethernet cable (Cat 5 unshielded twisted pair), and since he recently passed his Technician exam and we both have "radio stuff" on our minds, I tried to make the analogy between coax transmission lines and the balanced…
natevw - AF7TB
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How is a 1:1 current balun different from a choke?

I have a 10m dipole and am going to feed it with 50 ohm unbalanced feed line (coax). My understanding is the feed point of this style antenna is about 50-75 ohms, and since it is a balanced antenna I'm thinking I need some type of balun. I'm…
Java42
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overhead power-line safety

A set of utility lines, and above them some high voltage power lines, run almost directly over the backyard fence. Some radio antennas are situated so that they can't fall onto the utility or power lines. However the opposite is not true. It…
hotpaw2
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Why does ladder line generally have a lower loss than coaxial cable?

It is well understood in the amateur radio community that ladder line, window line, etc. have lower losses per foot than say RG-213 or LMR400, particularly on HF frequencies. It is also understood that this loss is a function of the RF resistance of…
Glenn W9IQ
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