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1500 questions
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Dipole antennas: Will paracord hold up well enough in the sun? Is there a better alternative?
Tower is up and pre-stretched multi-strand 14 Ga wires are cut & terminated for a multiband fan-style dipole antenna system. Location is the desert southwest of the USA.
Stringing up parts of it are going to be a challenge due to topography, and it…
SDsolar
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RF signal level when the antenna is disconnected
This is question a3a1-1 from the set of practice questions in the "amateur radio Exam Secrets" book:
An antenna is connected by a short feeder to the input to a radio receiver. Everything is correctly matched to 50Ω and a sensitive, high impedance…
Pablo Fernandez
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5
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How can I calculate the 1/4-wave monopole impedance dependence on groundplane angle?
I watched this video of a very nice explanation of a simple dipole and 1/4-wave monopole. In that video they show how you can impedance match the 1/4-wave monopole by bending the 4 (virtual ground plane) pins downwards at an angle, $\theta$, from…
not2qubit
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1 answer
Is hiding your voice on phone legal?
Lets say I use a computer to change my voices pitch, or use computer generated voices to hit a repeater. Is this allowed, or does it have to be my natural voice coming in on phone transmissions?
I am in the United States of America.
Skyler 440
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4
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3 answers
Relations between bit rate, frequency deviation and channel filter bandwidth
I just started using a couple of low power radio modules in my project (HopeRF RFM69HCW).
I made them work; they successfully transmit messages in a limited range (5-10 meters). Now I would like to improve that range (with a minimal message…
noearchimede
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4
votes
5 answers
Coax cable as antenna for 5 watt handy
For a normal 5 watt handy working in VHF or UHF freq with 50 ohm antenna , is it possible to use a same length coax cable instead of a stub antenna, so as to work like a crude antenna. Will this only result in extra capacitance/ VSWR damaging the…
user132257
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4
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7 answers
Slot antenna for 2 meter mobile
My primary vehicle is a Smart car, with a roof that's a piece of plastic(100% moon roof). Not the most awesome of cars to use for grounds. I'm building a bumper mounted antenna tower, EMT with some square tube. Earlier today I stumbled across an…
Omagasohe
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4
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3 answers
Do I need a license to operate as a ham in Haiti?
I am currently thinking about joining the shortwave radio community, and know that if I was going to operate one in the U.S., I would need a license to operate in a certain range. But I am not living in the United States, I am living in the island…
Mr.Zeus
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4
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3 answers
Is RF current always confined to the inner diameter of a braided outer conductor of coaxial cable?
Prompted by a previous question found at Using a balun with a resonant dipole -- an answer there included the following text:
"For transmission lines (twin-lead or coax) to not radiate, each conductor must carry equal and opposite currents. It's…
Richard Fry
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4
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1 answer
How Does the Performance of Elevated Radials Differ from That of Buried Radials?
NEC4.2 provides some information about this topic that may be of interest to some readers.
Richard Fry
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4
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2 answers
Use noise figure and gain to calculate weakest signal radio can receive?
An FM radio receiver, using a 1 kHz tone at 3 kHz deviation has a 12 dB SINAD (Signal To Noise and Distortion) of -116 dBm.
I would like to increase the 12 dB SINAD sensitivity of the receiver to at least -121 dBm to increase the weak signal…
Skyler 440
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4
votes
1 answer
How Does Earth Conductivity Affect the "Takeoff Angle" of a Vertical Monopole?
NEC4.2 gives some insight into this ...
Richard Fry
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4
votes
3 answers
Why are carrier waves necessary?
I am studying for the technician exam and I have come across the section on carrier waves, basebands, and various kinds of modulation.
It makes sense to me that you create a signal by combining the baseband, which carries data, with the carrier…
user11031
4
votes
3 answers
What is RF hash?
Ok, I get that "RF hash" is some sort of slang for "RF interference" (think CB), but does it refer to a particular type or source of interference? Do tell.
Noji
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4
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What type of signal is this?
I received this signal around 7 MHz. I've checked all over the "Signal Identification Wiki", but cannot find anything similar to this. I'm pretty sure this is some simple FSK, but that is the exact type?
The signal is at around 2200Hz (in audio…
Risahas
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