Amateur Radio Stack Exchange
Amateur Radio Stack Exchange

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1500 questions
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2 answers

Is Morse code allowed on FM in the USA

Let's say I get my little 2 meter FM handheld out and make a little sine-wave generator with which I pulse a morse code and if I connect it to headphones a speaker, I hear the dits and dahs of a nice sine wave tone. Now let's say I connect this to…
Skyler 440
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How does a slot antenna work?

How does a so-called slot antenna work? How can one construct one? What might be the radiation pattern and efficiency compared to a wire antenna? And, if a small slot antenna "works" at mobile phone cellular and radar frequencies, would a very…
hotpaw2
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How far does an antenna need to be from metal to avoid problems?

Living in an apartment, I'm struggling to get good antennas set up, especially for HF. Worse yet, I'm not allowed external antennas (but am willing to try something low profile on the balcony), my apartment is built with stucco (with the "chicken…
David KF4MDV
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Why must twin-lead conductor spacing be small to avoid radiation?

A transmission line does not radiate when the spacing between the two wires is very small when compared to the wavelength, but the transmission line begins to radiate when the spacing between the lines becomes comparable to the wavelength of the…
Danny Paul
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5 answers

How can I prevent my mobile radio from draining my vehicle's battery?

I'm a very absentminded ham. I have a radio mounted in my car, wired directly to the vehicle battery. Fuses and high-gauge wire and all that good stuff. But, if I accidentally leave it on, my battery will be dead by the next morning! I don't know…
Dan KD2EE
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What's the difference between "minimum SWR" and "resonance"?

Is the point of minimum SWR equivalent to resonance? Exactly what does resonance mean, anyway?
Phil Frost - W8II
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How is ARES different from RACES?

Just what the title states. Here, in India, in the context of public service we hear of RACES (Radio Amateur Civil Emergency Service). I recently learnt about something called ARES in a similar context applicable to CONUS. Yet RACES, as far as I'm…
VU2NHW
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Why do single band 10 meter radios exist?

I wonder why special radios for 10 meter band are manufactured? On the one hand - any fully-fledged HF transceiver includes 10 meter band. On the other hand there are no only "15 meter band" or only "80 meter band" radios. What is so special with 10…
user23772
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Using ham radio bands for telemetry

If I built a machine that went far away, say a buoy, would I be allowed to use ham radio frequencies to transmit telemetry data back to its base station, if I used my call sign? This is for personal research, not commercial applications.
Ken - Enough about Monica
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How do you choose an inductor wire gauge for high-power RF?

At 100 watts in a 50-ohm system, the current flowing through an inductor would be about 1.41 A, thus a 26-AWG wire should be plenty since they are chassis-rated for 2A and for just a few windings that isn't a very long wire. This answer indicates…
KJ7LNW
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Why are longer antennas not suitable to pick higher frequencies?

I know that the length of an antenna depends on the wavelength of the frequency it's trying to receive. A higher frequency needs a shorter antenna and vice versa. I can see that with a high frequency like 500 kHz, an antenna should be around 28,000…
Dan
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Yaesu VX-7R clock is running very fast

I just noticed the clock on my Yaesu VX-7R is running very fast. I noticed this a few days ago, where it would be days ahead. I would reset the time to the second and then, again, hours or days ahead. I'm not sure when this started happening, or if…
user21417
9
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3 answers

Will there be common-mode currents if a coax followed by a ladder line is terminated in a dummy load?

Assuming an antenna system where a transmitter feeds an ideal coaxial cable which is then connected to an ideal ladder line without a balun: It is often said that common-mode currents appear in the transition between a coaxial cable and a ladder…
rubund
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Why are PL tones strange numbers?

PL tones have very specific odd numbers with a decimal place like 103.5 or 107.2 or 88.5. The only PL tone that does not have this decimal is the 100.0 hertz tone. Why don't they just use integers with a standard increment of lets say 10 hertz so…
Skyler 440
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What regulatory issues/differences should I be aware of as a US ham vacationing in Europe (Poland)?

I am a US ham with an Extra Class ticket. If I were to go Poland (or possibly some other part of Europe) on vacation and bring some radios, what legal stuff do I need to know about? I know that my Extra Class license converts into a CEPT license…
krzysz00 KF5SOQ
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