# Tag Info

## Hot answers tagged coaxial-cable

23 votes
Accepted

### How does an SWR meter really work?

Dispelling the Myth To begin with, the typical HF SWR meter does not have the ability to separately sample the forward and reverse power, voltage, or current. Any description of the device or its ...
• 18.3k
13 votes

### I have 60 feet of coax but only need 20 feet; can I loop up the excess?

There's nothing inherently wrong with “looping up” extra coaxial cable. In fact, a neatly wound coil of coax can function as an air-core choke balun (“ugly balun”) which is useful for some antenna ...
• 23.7k
10 votes
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### Why is my calculation for added length of coax for a double cross antenna different to everyone else's?

The difference is the "Velocity factor". A 36cm long physical coax wire of this type is electrical 54.4cm long. Different types of wire have different velocity factors. https://en.wikipedia.org/wiki/...
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9 votes
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### Is "low loss" cable required for HF?

Your question seems as much about psychology as much as technical concerns. We mainly favor the technical questions, but I'll take a stab at the psychological aspects also. All of you, please feel ...
• 8,982
8 votes
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### Why isn't twisted pair used for feedlines?

Balanced lines (of which twisted pair is a special type) really have an upper frequency limit; you can't use them to transport 1 GHz (well, you can, but the smallest variation in direction or distance ...
• 14.7k
8 votes
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### Does a balun need to be made with coax?

I'll explain the operation of that balun very briefly: for the differential mode (which by definition has equal but opposite currents on each conductor), each conductor induces an equal but opposite ...
• 50.8k
8 votes
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### Soldering PL-259.. with a torch?

Our friends in the UK and other parts of the world are now wondering how you could even begin to solder a PL259 connector with a torch (aka flashlight)! But in their vernacular, you of course are ...
• 18.3k
8 votes
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### VHF 50 Ω Antenna Over 75 Ω TV Coax

I will need a UHF/VHF diplexer on either end to suitably merge/split the signals from each antenna Yes, this is correct. A tangent: If you wanted to save some money by using mass-market parts, ...
• 23.7k
8 votes
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• 1,646
6 votes

### Can ferrite beads lower coax cable velocity factor?

For well-designed coax, the EM fields are confined to the space between the inside of the braid and the center conductor, i.e. the dielectric insulation region which affects the velocity factor. ...
• 1,646
6 votes
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### Recomended coax for 100ft (2m/70cm)

According to this online coax loss calculator, the loss of 50 feet of new Belden 9258 RG-8X with an antenna with an SWR of 1.5 is 4.29 dB at 450 MHz (UHF), so the loss for 100 feet of the same coax ...
• 8,982
6 votes

### One cable two different radios

You need a switch. Connecting two transceivers directly to one antenna is a great way to destroy one of them — as soon as you transmit with one, the receive circuit of the other one will see several ...
• 10.7k
6 votes
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### How to calculate coax cable loss for lengths other than 100 feet

It's the first one, if you use 50 feet (1/2 the length) then the loss is 20 dB / 2 = 10 dB. similarly, if you used 200 feet, the loss would be double… 20dB + 20dB = 40dB loss. there are several online ...
• 3,044
5 votes
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### RG-174 to pull signal from 1st IF?

So, you say: I don't care if the signals are delayed. I'm just tapping the line out to a pan adapter. I am most concerned about influencing the existing function of the receiver And that's exactly ...
• 14.7k
5 votes

### How is a 1:1 current balun different from a choke?

The name choke refers to the electrical component, whereas the name 1:1 current balun refers to the job it is doing. There's more than one way to construct a balun. There are purposes for a choke ...
• 23.7k
5 votes
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### Understanding coax radiation and "current on the shield"

Perhaps some of my confusion comes from an audio background, where one has "balanced" and "unbalanced" cabling in a way that is easier for me to understand: an unbalanced cable is simply a signal and ...
• 50.8k
5 votes

### Does a balun need to be made with coax?

Short answer: No, and in fact you'll often get more bang for your buck by avoiding coaxial baluns. The description of the balun's purpose in an antenna system you quote is an oft repeated bit of "...
• 1,824
5 votes
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### Use a TV coax and balun for a poor-man's OCFD?

OK, let me try to answer this, but this answer may also be qualified as unqualified. If you have a 50 Ohm receiver, and connect a perfectly (Z=R) 75 ohm antenna system, then your VSWR would be 1.5, ...
• 2,107
5 votes
Accepted

### Why is the insertion loss of my coax cable higher than expected?

Based on your description, I would suspect moisture damage. Moisture ingress in coax cables typically results in the corrosion of the copper braided wires in the shield. The oxide that forms ...
• 18.3k

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