Amateur Radio Stack Exchange
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1500 questions
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1 answer

Why do people say, "get a nickel," on repeaters?

Sometimes, I'll hear someone say "wait a moment, I'm getting a nickel," and then drop the carrier only to resume talking. Why?
webmarc
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5 answers

Good wire for wire antenna?

What properties should I look for in a good wire for building a wire antenna? Could anyone recommend something specific for me?
Timtech
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What antenna on a BaoFeng UV-5R Pro will give me better reception?

I am happy with my BaoFeng UV-5R Pro but the local UHV VHF repeater and simplex reception is terrible, even for contacts less than 50 kilometers. I assume that it's because the rubber-ducky antenna on it is terrible. What can I replace it with that…
Warren VE3WPX
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How to detect common-mode currents or “RF in the shack”?

Let's say we already know that if your antenna is not suitably constructed or connected then you can get current on the shield of your coaxial feed line which will flow through the shielding/grounding of your equipment, becoming “RF in the shack”,…
Kevin Reid AG6YO
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What makes cellphone transmissions so energy cheap?

The modern cellphone can carry on a full duplex conversation for a time period measured in hours on a battery half the size of my handheld transceiver. My transceiver can barely receive for that length of time on its pack, nevermind transmit, and…
Adam Davis
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19
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1 answer

How does moving a feedpoint off-center in a dipole affect the resonant frequency and resistive load?

Specifically, I understand that OCF dipoles change the SWR, but does it do this via reactance or resistance, or both?
Bill - K5WL
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Why do folded dipoles have greater bandwidth than ordinary resonant dipoles?

This is something I've read in passing, but never encountered an explanation of why. For example, Wikipedia says: Another common place one can see dipoles is as antennas for the FM band; these are folded dipoles. The tips of the antenna are folded…
Phil Frost - W8II
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3 answers

How does a mag mount antenna achieve a ground plane?

I've been thinking for some time about magnet mount mobile antennas and wondering how they establish their ground plane. Consider that many mag mount antennas have some kind of protective coating on the magnet. Consider also that most cars have a…
Peter KB1AVL
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19
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SDR sampling bandwidth - do the bits per sample matter?

I'm looking at data converter chips for a homebrew SDR design, and I see that I can choose not just the sampling frequency, but also the bits per sample. Obviously the sampling frequency has to be several times the target frequency, but what effect…
Adam Davis
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What's the pinout for "Kenwood" 2.5mm TRS/3.5 mm TRS connector?

I've seen many Chinese HTs (Baofeng, Puxing, Wouxun, QuanSheng etc.) using the so-called "Kenwood connector", which has a 2.5 mm TRS connector and a 3.5 mm TRS connector. It looks something like this: I've seen it used for serial ports, speakers,…
AndrejaKo
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FCC sends "Notice of Dismissal" with quite threatening language just for denial of a vanity callsign?

I had applied for a vanity callsign which wasn't available. That was in March. The FCC license system shows my old callsign is still in effect. Today, after a longer absence from my mail, I open a "Notice of Dismissal" which says in a wordy way lots…
Gunther Schadow
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5 answers

What do "QRM" and "QSB" refer to?

An answer on Basic QSO format? mentions things like "QRM" and "QSB". What do those terms mean?
Amber
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3 answers

Why do amateur radio operators call an RF choke a balun?

When using a balanced antenna such as a half wave dipole, with an unbalanced feed line such as coax, an RF choke can be used to block RF current emitted by the transmitter from splitting up at the antenna feed point and traveling along the antenna…
Andrew
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6 answers

Using a Morse code key with a computer?

Are there standard ways to connect a hand key (straight or paddle) to a contemporary computing device (PC laptop with no parallel port, Mac, Android, iOS device, etc.) for developing or improving ones Morse code sending skills? If so, can one use…
hotpaw2
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SDR: Quadrature demodulation vs direct RF sampling

I see that many SDRs use a quadrature demodulator and sample I and Q signals. But is it possible to downconvert the RF signal instead, sample it with only one ADC, and get the same capabilities of digital postprocessing? So if we want to observe…
BarsMonster - R2AYN
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