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Questions tagged [coax]

Coaxial cable, or coax, is a type of cable that has an inner conductor surrounded by a tubular insulating layer, surrounded by a tubular conducting shield.

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Coax DTF Frequency Span

Hopefully, we have some RF transmission train drivers on board. My question pertains to what start and stop frequencies to use when making coax Distance-to-Fault (DTF) measurements on a VNA like an ...
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Driving 50 Ω coax cable for doing measurements with oscilloscope

This is a follow up question to Using 50 Ω coax cable instead of passive probe. In the linked question I asked whether it would be possible to use a 50 Ω coax cable instead of the passive probe for ...
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Correct connection of a Wi-Fi board having both printed antennas and U.FL sockets

An RF part of a dual antenna Wi-Fi module from Aliexpress. We can see coax sockets connected in parallel to printed antennas. Two external antennas and corresponding pigtails are part of the package. ...
ololo ololo's user avatar
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In cable TV, what prevents an user added channel from propagating downstream?

A cable TV user can use an RF modulator and a coaxial splitter/combiner to add a video signal, in an unused channel, to the coaxial cables running in their home. What prevents this new channel to ...
peppermint0008's user avatar
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Coax cables and input impedances

I'm doing a voltage measurement with the help of an Active Differential Probe (TESTEC TT-SI 9010) with an output voltage of +-7V. This voltages have rise times of the order 500ns. The set up looks ...
Santi Ospina's user avatar
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Shielding WiFi signal

I have a device with WiFi connectivity. I want to shield this device from the outside, so no one can connect with the device, no matter how near he stands to it. My device has a small antenna which ...
Maxim's user avatar
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My sourcemeter lets me do a four probe connection using banana connectors or tri-ax. What do the extra lines on the tri-ax do?

The Keithley 2450 sourcemeter has two ways you can do a 4-probe measurement: in the front there are four banana connection ports labeled SENSE HI, SENSE LO,FORCE HI, and FORCE LO. In the back, there ...
Roy's user avatar
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RCA coax end termination

I am building an amplifier that takes in an RCA output from a TV. From my general understanding, RCA coaxial cables typically have an impedance of either 50 Ω or 75 Ω and a small amount of capacitance ...
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Why aren't baluns needed for a monopole to unbalanced coax connection?

I've asked before regarding dipoles connected to unbalanced lines. From what I gathered, the current in the inner shield when reaching the dipole (in transmitting case) can either go into the pole ...
George kirby's user avatar
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147 views

AC leakage issue with high impedance measurement setup

I am having an AC leakage current problem with my measurement setup that I typically use for lock-in measurements. I employ a 100 M\$\Omega\$ resistor as a voltage-current converter, and in series, a ...
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Coaxial quality and frequency rating

Context I aim to start playing with RF and the first thing I wish to do is some EMI tests. I've been watching YouTube videos on the matter as you do, and I've seen plenty of people using SMA ...
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Is propagation delay in coax cable a function of signal frequency?

For this coax cable, the propagation delay is given as a single parameter in 1.54 ns/ft as follows: But isn't the propagation delay function of signal frequency?
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Directional coupler frequency range

If a directional coupler is labeled 5-1002 Mhz, what happens to frequencies above that? Is that just the rated frequencies but above that may work fine, or does that mean it blocks everything above ...
Pascal's user avatar
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Ansys AEDT and Icepak Simulation

I have designed slotted coax cable based waveguide and FR4 is not getting any heat and even the coaxial cable does not get any heat which I do not understand why. E field as follows, ports include 2kW ...
Nurullah Çetin's user avatar
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What are these PCB coax holders called?

I have RG6 coax which I need to attach to a board and would like to use a strain relief method as shown here: What are these connector "claw grip" things called? I believe this "claw ...
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How can I attach a PCB patch antenna with microstrip feed to coax cable without soldering

I designed a patch antenna on a 1.5 mm thick substrate for 7 GHz. It has to be connected to a semi rigid coax cable. Due to the application it is meant for, I can not solder a SMA connector or the ...
PixSim's user avatar
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Connecting microwave oven magnetron with coaxial cable (for a simple plasma torch)

I would like to try and build a basic microwave plasma torch using an oven magnetron. I've had experience with S-Band RF back in my physical chemistry days but am not liking the prices for waveguides. ...
nitrous dude's user avatar
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Coaxial connector with a #2-64 thread

We've been tasked with considering an existing design for coaxial bulkhead connector (breaching a pressure vessel). One end of the bulkhead has a relatively common 'Microdot' / 'S-50 series' coaxial ...
Chris Knudsen's user avatar
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5 answers
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Why do cables specify 75 Ω impedance when impedance is a two-dimensional quantity?

As I understand it, impedance has an imaginary and a real part. To be able to perform any useful calculations, one needs to know both. Cables and speakers usually only say like "8 Ω" or &...
Stephen Hubschrauber's user avatar
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Mid-bandwidth data and power over coax

I am interested in transmitting both digital data and power over a single coaxial cable between two FPGAs. Communication should be at least half-duplex. Communication speed should be on the order of ...
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What is the maximum current that a 5V barrel plug device will draw if plugged into USB-A?

Here's the situation, I have an alarm clock that is powered by a barrel plug DC connector that says "5V" next to it. Out of the box, it has an AC plug into a figure-8 connector going into a ...
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Is it possible to properly solder SMA connectors to flexible coax (RG400)?

It looks like only crimp connectors are widely available for flexible double-shielded coax cable like RG400. There is also wide availability of solder connectors for semi-rigid cable like RG402 (but ...
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Signal path between nodes in a MoCA network

I'm trying to understand how signals propagate between nodes in a MoCA (Multimedia over Coax Alliance) network. For example, in a typical but simple network, one has a coax input from a service ...
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What happens to the signal and antenna pattern when the coaxial shield of the feedline is severed?

Assuming a single-shielded coaxial cable connected between a transceiver and antenna, what would happen to transmitted signal and the antenna's radiation pattern if at some point along the feedline ...
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Induced voltage in inner coax conductor due to current in outer coax conductor, how is it possible?

I have been reading "noise reduction techniques in electronic systems" by Henry W. Ott, on chapter "Magnetic coupling between shield and inner conductor" it's written: the voltage ...
Oleksiy Deliyev's user avatar
1 vote
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1k views

Difference in Triax connector types

What is the difference between TRB and TRC? What do they stand for? what are they referring to exactly? While we are on this subject, what are TRT, TTM, TRX, TRS? I have scoured the internet with no ...
himura's user avatar
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Can I connect S/PDIF line from TOSLINK to coax?

Since the original analog audio in my device (MiSTerfpga) is bad, I'm using an external TOSLINK-to-RCA-stereo DAC. Now I'd like to merge this setup into the device. I'd like to know if wiring the S/...
Alex's user avatar
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1 vote
1 answer
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How can I match the impedances in this circuit?

I have a pre-amplifier with 93.1 Ω output impedance connected to a main amplifier with input impedance of 1000 Ω via 75 Ω co-axial cable. The signals are very small pulses from a measurement device ...
b7031719's user avatar
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261 views

What do I need to connect an R-SMA male to a standard coaxial male? [closed]

I have a router that has the following type of pigtail connector soldered to the board which I believe is an R-SMA male coaxial cable. I'd like to connect it to a standard male coaxial cable that's ...
Bobby's user avatar
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2 votes
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How is the center pin supported in air-filled coaxial cables?

In SMA cables, the PTFE dielectric supports the center pin through the length of cable. How is the center pin supported in air-filled cables? E.g., 3.5mm, 2.9mm, K-connector, 1.8mm, V-connector, etc. ...
qtc0's user avatar
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11 votes
2 answers
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Is there ever a good reason to ground a coax cable on one side only?

In a recent amateur radio build, I deduced (most likely incorrectly) that a longish (maybe 20 cm) length of power cable carrying DC voltage to an IF board could benefit from some shielding. Careful ...
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Can telescopic FM/DAB antenna be replaced by Coax?

I tried to search for this prior to asking but with no luck... I have an FM/DAB+ antenna like this: from which a standard 75-Ohm Coax is coming down and I would like to connect it to the radio (...
player0's user avatar
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Coax cable 130 dB vs 135 dB, which one is better?

I need to buy some coax cable for TV via satellite. I see they are marked in dB: 135, 130, 120 down to 95. Then there are multiple layers (up to 5) and shielding copper (cu) vs aluminum (alu.) Is my ...
Roger's user avatar
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3 votes
1 answer
590 views

Two devices sharing the same coaxial cable, what frequency channel should I chose? [closed]

The 2-stories house is equipped with a coaxial cable that has wall plugs in 1st and 2nd floors (it's also connected to the antenna on the roof). Our IAP installed a modem for Internet (Arris CM820C) ...
Déjà vu's user avatar
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RF pickup noise through coaxial cables and connectors [closed]

We use RF antenna to transmit RF power in the near field regime. The typical wavelength is ~ 10 MHz whereas the antenna itself is only a few cm long(3 loops of a copper wire). We see that for a power ...
sudipta's user avatar
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8 votes
3 answers
2k views

What causes common mode currents in a coaxial cable?

I have been messing around with a signal generator, an RF current probe and an open ended coax cable. From about 50 MHz onwards, I can measure a significant common mode current if I attach some wires (...
Cyrus Tirband's user avatar
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156 views

How to switch off the CATV signal on a splitter port

I'm trying to create some automation of switching off the CATV signal on a splitter port. Using a regular 5V Arduino relay module I've tried to interrupt the wire from the center of the coaxial cable ...
Mne's user avatar
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2 votes
2 answers
992 views

What is this metal box with BNC connectors for?

I found this box with a schematic drawn on it. What is it for?
Tristan19's user avatar
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1k views

Differential signals in micro-coax

I have seen many applications where micro-coax is used for differential signals. For example display panels with LVDS or eDP, and a I-PEX VS type connector. The I-PEX connector even names USB4, HDMI ...
Klas-Kenny's user avatar
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2 votes
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Coaxial Cable with signal applied to shield and center conductor grounded

The standard way to drive a signal through a coaxial cable is to have the shield grounded, and a single-ended signal applied to the center conductor. (Throughout, I will assume that \$R_{term}\$ and \...
Math Keeps Me Busy's user avatar
5 votes
2 answers
1k views

Why don't oscilloscope probes use twisted pairs?

I was reading online about how Ethernet cables use twisted pairs instead of coaxial cables because it's better in some way. Some websites say that twisted pairs cost less, can carry higher frequencies,...
loadingnow's user avatar
1 vote
1 answer
967 views

Why are Coax-to-Ethernet converters causing the entire network to stop working?

I have installed nine of these Coax-to-Ethernet passive converters, which allow me to use existing coax cables to transmit Ethernet traffic from IP cameras. This was necessary due to the inability to ...
Ryan Griggs's user avatar
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1 vote
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Can alligator clips be soldered to PCB pads?

I have a coaxial Teflon wire that is carry some high voltage signal. I do not want to solder it directly to the PCB pad as there can be issue of short circuit as there are components placed nearby the ...
abunickabhi's user avatar
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How to quantify Td and Z0 for a given length of RG-58 coax cable in LTspice?

I want to simulate a current source (on the left in below) is connected to a scope input via a meter long RG-58 coax cable. But, I cannot figure out what should Td and Z0 be. I only found the coax ...
GNZ's user avatar
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1 vote
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Instrumentation for high frequency pulse

to be updated... I have an optical pulsed laser source (has no manual.) Its monitor output has on its certificate for at 3MHz frequency stated as 0.5 ns pulse duration (ON time.) The output supposed ...
user1999's user avatar
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2 votes
2 answers
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What does a 50 ohm coax "look like" when neither the source nor the load are matched to it, and the center conductor and shield are used for signals?

Say I have a π-network filter for which the inductor is on a separate board. For convenience, I use a 50 ohm coax (4" long, frequency is 13.56 MHz) to connect to the inductor, using the center ...
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Replace a short length of triaxial cable with a PCB transmission line

I am working on a project that benefits from a short (~1") length of triaxial cable. At first I was skeptical that the cable would have any effect given its short length, but the performance is ...
cholz's user avatar
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Is there a wired block wifi signal amplifier?

I already have a directional wi-fi 2.4 antenna with a gain of about 25 dbi. I also have an adapter, however, the power of the receiver/transmitter is not enough. My apartment is on the 9th floor, ...
Alex A.'s user avatar
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4 votes
2 answers
545 views

Modeling bidirectional communication across a coax?

I was reading about the history of cable internet and I'm interested in a simple model of full-duplex communications across a single coaxial cable. My first attempt is simply a transmission line with ...
Mark's user avatar
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How do terminate the coax shield of AC coupled LVDS signal? (isolated grounds)

I have an LVDS clock signal that goes to several PCB cards. Frequency: 100Hz --> 20MHz I am going to use a fan out IC to supply each card with it's own buffered CLK signal; I am not going do a '...
Tony's user avatar
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