Questions tagged [coaxial-cable]

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

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Snap on choke on coax line leading from radio. Wrapped an LED around the choke and it lights with transmission, but only on certain bands? SWR?

Why does a LED wrapped around a snap-on Choke attached to radio antennae coax only light up when transmitting on certain bands? Is this an indication of high reflected power in the braid inducing ...
Hetzal Hartley's user avatar
0 votes
1 answer
114 views

Suggestion for the RF cable

I am setting up a HAM antenna (50 ohm) on my house terrace. The cable length is going to be around 25 meters from terrace to my transmitter. Which type of co-axial RF cable should I choose with low ...
enemra's user avatar
  • 29
2 votes
2 answers
114 views

Long Distance antenna feedline for UHF/2.5GHz signal

I'm building a boat towed underwater platform. This underwater platform has a single board computer with a remote wifi antenna connection via a u.fl connector. I'm experimenting around with a way to ...
leeprevost's user avatar
4 votes
2 answers
299 views

Coax in the wall, or around the house?

I am mounting a hex-beam antenna to the peak of my house (assuming that I can find someone with a cherry-picker or a scissor-lift that can help me get it up there). Right at that end of the house is ...
Don Levey's user avatar
2 votes
1 answer
96 views

How to calculate phase constant for a coaxial cable?

inner and outer conductor diameters of 1 mm and 5 mm respectively, is filled with a non-magnetic PTFE dielectric having εr = 2.55. frequency = 1 GHz.
Praskand's user avatar
3 votes
4 answers
466 views

Using UV5R HTs. Will i lose receiving range by attaching coaxial cable to put my antenna remotely as well as higher?

Using beofeng UV5R HTs. Changed antennas to retevis whips. Will adding coaxial cable to HT & antenna for height reduce or increase reception. As i'm in a valley. I receive only. As i'm still ...
Snowy's user avatar
  • 63
3 votes
3 answers
311 views

Dipole antenna using current on outside of coax as intentional radiator?

Is there an antenna design somewhat like a coaxial dipole, where the coax ends in a quarter-wave radiator, but instead of an explicit coaxial radiator running back over the coax body, the outer ...
ralph vanhoek's user avatar
0 votes
2 answers
105 views

Attaching a bulb to amplified coax cable will it light?

I am IT person not Ham operator and I guess it is difficult for you to understand me and my different thinking so this is a very simple question that will probably answer the dilemma at Coaxial cable ...
Svetoslav's user avatar
0 votes
1 answer
130 views

What happens with LNA in bidirectional communication? [closed]

I want to ask that if you have a cable that has started with 40dbm source signal and has reached -10dbm then you put LNA (the end of the cable will be plugged to RFIN), then attach the RFOUT to ...
Svetoslav's user avatar
0 votes
1 answer
161 views

Coaxial cable loss, dbm, db correlations

I am very confused how ham operators deal with all this, because most of the information in internet is controversial. I have coaxial cable with loss of 34dB at 100 meters at 2400mhz. People say that ...
Svetoslav's user avatar
0 votes
4 answers
132 views

Wired RF connection without antenna

I’d like to build a radio system for use in underground caves. Wireless signals are nearly impossible to propagate in this environment, so I’d like to run long coaxial cable between each station. Are ...
Elliott B's user avatar
  • 101
4 votes
1 answer
535 views

Using NanoVNA to tune antenna

I'm extremely new to this, so I'm mostly asking for tutorials and so on. I have tried configuring the device according to one tutorial I found. When I hook up the cheap antennas that came with a ...
Jesse Knott's user avatar
3 votes
1 answer
158 views

Coax when skin depth is thicker than the shielding

Considering coax cable's operation is based on skin effect and shild current flowing on the inner side of the shield how does it work when the skin depth for a given frequency is more than the foil ...
axk's user avatar
  • 133
0 votes
3 answers
176 views

Ohms & coax cabling miscalculation?

I measured the resistance for 15 meters RG6 cable, which showed 3 ohms on my multimeter ! I've got 0.7 ohms resistance on the multimeter itself when touching the negative and positive. So 3 ohms - 0.7 ...
Svetoslav's user avatar
3 votes
2 answers
202 views

Does a halfwave (or multiple) length of coax duplicate the load impedance of one end at the other end?

Ignoring the possibility of multiple radiators and phasing harness(es), consider the following example: If I have a short inductor-loaded vertical antenna that I have not carefully matched to 50 ohm ...
always_learning's user avatar
2 votes
1 answer
137 views

Is a 1/2-wave coax cable shorter or longer than the full-speed 1/2-wavelength?

If I want to cut a half wavelength segment of coax for the two-meter band and the velocity factor is 85%, is my cable going to be shorter or longer than a meter? I'm trying to figure out if the ...
KJ7LNW's user avatar
  • 723
2 votes
1 answer
221 views

What is minimum safe bend radius for rg213?

What is minimum safe bend radius for rg213 cable?
quanglewangle's user avatar
2 votes
1 answer
183 views

Antenna from the roof / coax cable to Ham and Weather radios

Just want to make sure I don't need anything else (to prevent damage to the radios) I have an antenna on my roof. It used to be used for TV but I switched back to cable. Can I literally just use a ...
vnat's user avatar
  • 21
3 votes
3 answers
440 views

Does Velocity Factor pose a significant cable loss?

We know that a lower Velocity Factor translates to using shorter runs of cable in resonant circuits. That apparently means that there is resistance to the flow of electrons, slowing them down. So ...
Dax's user avatar
  • 453
0 votes
1 answer
211 views

Is 100m too long for hf feed wire?

I have room to erect a DX Commander, multi-band vertical, and to give it a good number of radials on a good clear site. Problem is I would need to run about 80 - 100m of coax feed from operating ...
quanglewangle's user avatar
2 votes
1 answer
189 views

Connect mobile device with coax cable to SDR board

My goal is to connect mobile devices using a coax cable with a SDR board to be independent from using the air interface and antennas. I don't know how to connect my devices with the SDRs since I'm an ...
k_o_'s user avatar
  • 123
0 votes
1 answer
203 views

TV Coax cable for QFH antenna

I'm new to this hobby and I'm trying to make me a QFH antenna for NOAA satelites myself. I would like to know if I can use AC15-380WH 4/8K TV coax cable with double ...
Marcel Kopera's user avatar
4 votes
2 answers
236 views

2-blade or 3-blade coax stripper: when would you use one vs the other?

I've been looking for a RG8x/LMR240 coax strippers and found that they come in both 2-blade and 3-blade models. So far I haven't found a reason to use one over the other. I did notice that the 3-...
KJ7LNW's user avatar
  • 723
3 votes
1 answer
120 views

What are the implications of increasing the coaxial cable length using connectors?

So the antenna spine (suspended line that was holding up the centre insulator) came apart. I've moved the centre insulator elsewhere. The move means my existing coaxial cable is now around 40ft short. ...
VU2NHW's user avatar
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2 votes
2 answers
1k views

Can I feed multiple different band antennas with one coax?

Can I feed multiple different band antennas with one coax to the transceiver?
marthien tarihoran's user avatar
3 votes
1 answer
170 views

Testing old coax cable

I have a situation similar to this: Testing for 'Bad' Coax . In addition to checking for DC continuity or shorts, here was my test method: My 50Ω dummy load (Elecraft DL1) has a diode and ...
Duston's user avatar
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1 vote
0 answers
229 views

Is this amount of loss normal with LMR400?

I have a run of about 150 feet of LMR400 (specifically, it's this DX Engineering "400MAX" product). It connects to an Ed Fong antenna (2m, 1.25m, 70cm tri-band J-Pole) about 75 feet up a ...
User5754448's user avatar
2 votes
3 answers
216 views

Is a UHF connector any real disadvantage off the transmitter circuit board or at an antenna feedpoint?

I have a discone antenna intended for use in the 25-1300 MHz frequency range, but it uses a SO-239 connector. Now, we know that the so-called "UHF" i.e. the PL-259 male plug and SO-239 ...
natevw - AF7TB's user avatar
4 votes
2 answers
752 views

VNA basics, antenna coax cable

Recently purchased my first VNA (Nano VNA) and I'm trying to learn the basics. I have a 150MHz 1/4 wave whip antenna that I need to install on a large metal object so I was hoping to use a VNA to help ...
P_J's user avatar
  • 43
2 votes
1 answer
485 views

RG-174 vs RG58 for winding toroid

I'm building a balun for a fan dipole, and this chart suggests 9 turns of RG-58 on two FT240-31 cores will give good performance over the frequency range of interest. However, I don't feel confident ...
RoadieRich AE8RL's user avatar
5 votes
3 answers
1k views

What kind of soldering iron is best for PL-259 (UHF) connectors?

What do you use to solder connectors onto bulk coax cable? Soldering the UHF connector to the coax shield on a PL-259 is described as requiring a bit of "experience and skill" in Dave Casler'...
Dax's user avatar
  • 453
5 votes
2 answers
1k views

How to calculate coax cable loss for lengths other than 100 feet

Cable loss for coax is mostly given in loss per 100 feet, express in dB. Say I have cable which is 20 dB loss per 100 feet at frequency x. If I use 50 feet (1/2 the length,) would my loss be: 20 dB /...
KevinHJ's user avatar
  • 215
2 votes
2 answers
60 views

How should I think about "extra" impedances inserted within/across a transmission line?

I'm worried this might be two separate questions — or perhaps not any coherent question at all? — but some recent thinking about transmission lines made me realize I still don't know how to think ...
natevw - AF7TB's user avatar
2 votes
1 answer
427 views

High electrical noise only when coax shield is connected

I'm trying to understand a noise issue on my Yaesu FT-891. I have very high 60 hz electric buzz on most bands with 40 and 15M being the worse at about S9+. My antenna is a MyAntennas 66ft EFHW fed ...
Don James's user avatar
2 votes
1 answer
60 views

Coaxial cable identification

Is there a way to identify this coaxial cable? I am interested in model and parameters such as epsilon, diameters etc. There is nothing written.
Pierre Polovodov's user avatar
2 votes
2 answers
188 views

How to choose antenna "pigtail" pragmatically?

I'm starting to tinker with an RTL-SDR (generic, and cheap, so nothing fancy in any respect, hence the "pragmatic" in my question title). It's clear that the antenna provided (about a foot ...
Toby Eggitt's user avatar
2 votes
1 answer
1k views

Need advice for running coax for HF to my shack

I'm looking for advice for running coax cable to my shack on the second floor of my house. I'm planning to use this coax line for HF (recently upgraded to General!). I'm a newbie and I am very handy, ...
kr4sh's user avatar
  • 367
2 votes
1 answer
163 views

can i convert an FM coaxial antenna to just speaker wire?

I have a Sony MHC-GX450 compact mini stereo system. The connector for the FM antenna is coaxial, and is labeled 75 Ω. I'm wondering if somehow I can use speaker wire for the FM antenna.
Brittany Russell's user avatar
2 votes
3 answers
161 views

Velocity Factors of Military Spec Coaxial Cables. Are they accurate and consistent in the real world?

I would be very interested in any real life data collected by fellow radio enthusiasts in regard to the velocity factors stated for milspec coaxial cable. e.g., RG213, RG58. How accurate and ...
Francis Archibald's user avatar
4 votes
3 answers
575 views

RF ground confusion

I'm a bit confused by RF grounding. Let's take a HF 1/4 wave vertical antenna for example. When current flows through the centre of the coax to the antenna, my understanding is that the current then ...
Engineer999's user avatar
6 votes
5 answers
2k views

Grounding a vertical antenna from a balcony

I have a multiband vertical antenna mounted onto the railings of my balcony apartment high up on the 6th floor of an apartment building. The antenna is not grounded. This antenna comes without radials....
Engineer999's user avatar
2 votes
1 answer
137 views

One cable two different radios

I have a GMRS radio and VHF/UHF radio in car. I have an antenna mount and cable installed. I install appropriate antenna for the radio in use and manually remove and attach cable to matching radio. It’...
Merlynda's user avatar
2 votes
1 answer
252 views

When to use air dielectric cables for antenna installation

I'm putting up antennas on a tower, and have a couple of 7/8" cables style on hand. One is Hj5-50 air dielectric cable and the other AVA5-50 "Virtual Air" cable. I notice that the HJ5 ...
Frank's user avatar
  • 339
3 votes
2 answers
546 views

Ground plane reflects RF or brings it to ground

I'm still confused with the purpose of a ground plane purpose in an antenna. My understanding is this. If an antenna is perfectly balanced, there will be no common-mode currents going to ground. If an ...
Engineer999's user avatar
5 votes
3 answers
911 views

When a dipole antenna is fed via coax, what powers the ground-side of the dipole?

I've been trying to understand how dipole antennas work, and I believe I understand the basics when they're fed via a balanced feed line. In fact, every dipole physics YouTube video and web page I can ...
Asker2093022's user avatar
1 vote
1 answer
132 views

Replacing a N-connector with SMA, easy?

I purchased a cell phone booster for the cottage that came with an external yagi. Since its important to get the antenna as far away as possible from the indoor omni, the yagi has about 25 meters of ...
Maury Markowitz's user avatar
3 votes
1 answer
4k views

Recomended coax for 100ft (2m/70cm)

I recently moved to another house. My setup's current coax is 50ft/RG8x/PL259 (bought in 2018), but it is not enough for connecting my antenna to where I want to place the radio. I believe that 50ft ...
KP4MCG's user avatar
  • 217
1 vote
1 answer
111 views

How do I connect a homebrew antenna using RX-8 to a Yaesu FT-70DR (SMA)?

I made an 2m / 70cm tape measure antenna using RG-8 coax. That part was quite a bit of fun and went fine. But when I tried to connect the coax to my Yaesu FT-70DR, the copper core of the RG-8 was too ...
David Wiley's user avatar
1 vote
0 answers
47 views

J Pole, what is the best way to deal with Common Mode Current? [duplicate]

I am planning on utilising a ferrite choke on a J Pole antenna for CMC. Placement directly on the feedpoint poses possible mechanical restraints. Is it okay to place it a quarter wave down the coaxial ...
Francis Archibald's user avatar
0 votes
2 answers
2k views

How to use 75ohm (RG6) coax?

I know that there have been many similar threads on this, but I still need clarification. At the moment, the only thing I have is a 500' roll of RG-6 and a (very) tight budget, and I should be ...
Galaxy's user avatar
  • 199