Amateur Radio Stack Exchange
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1500 questions
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2 answers

Why is an RF ground not as critical as the other, and can they be used backwards?

I will give the magmount antenna as an example: The vertical element to the antenna is very critical, cut to a certain wavelength, often added with some loading coils, or a little spiral to make everything perfect for the specific frequency. The…
Skyler 440
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Is there a "proper" phonetic alphabet to use with voice communications?

When I took my Technician test some 20 years or so ago, we had to memorize the phonetic alphabet, which I think is the same one used in the military. I was taught that it was international, similar to morse code. It used words such as "Mike" for the…
ghendricks
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What does sending SK after calling CQ mean?

When I was at a local radio club today, I witnessed a bit unusual response by a station calling CQ using BPSK31, that is to say phase-shift keying, not the regular A1A telegraphy, on the 20 meter band. The communication looked something like…
AndrejaKo
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Identifying regulations for interfering stations

I'm working on tracking down some 2m repeater interference, and I have identified that the offending signal is a spur transmission on a commercial pager service (that lands right on our repeater input frequency). How would I identify regulations…
W5VO
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FT8 callsign/maidenhead compression encoding

I have set myself a challenge to write a Matlab script as proof of concept to send an FT8 CQ call (not necessarily for live transmissions yet, but I may extend the project). So far I have: Generated and appended 14-bit CRC to precomputed message…
jemussi
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Is a VHF antenna on a vehicle's body a bad idea?

For context, I'm brand new, with nothing but an HT & 19" dual band (2m/70cm) whip on it. While I'll likely go with a magnetically mounted vertical antenna, I've been thinking of other more covert options. For instance, could I do a 1/2 wave dipole…
conan
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Coax fed dipole: shield goes to one side, yet is grounded via chassis line to Earth

Suppose I have a coax-fed half-wave dipole antenna. The coax shield goes to one side of the antenna, the center conductor to the other side. The transceiver's chassis is connected (via the coax connector) to both one side of the dipole and to Earth…
Jack
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Why is the electric field orthogonal to the magnetic field from an antenna?

I've read in several places that the electric field is 90 degrees orthogonal to the magnetic field, and both are orthogonal to the direction of the wave from a transmitting antenna. What causes this? Are there any cases where this might not be true,…
Adam Davis
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Why are there no amateur allocations in the LF and VLF spectrum?

Amateur radio enthusiasts have slices of spectrum at every magnitude of spectrum MF and above, but in the US none are below MF. Why are there no spectrum allocations below 160M?
Adam Davis
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Morse Code Key Grease

I just got an old brass key at a hamfest, and it appears to be in pretty good mechanical condition, aside from some dirt and dust. Taking it apart, the key (apologies for not knowing the exact terminology) is held in place by two cups with four ball…
W5VO
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What will I need to receive the ICE/ISEE-3 transmitter?

The ICE/ISEE-3 spacecraft, launched in 1979, is due to pass by the earth in August, 2014. It was commanded to power down completely years ago, but it appears to have failed to do so, and while it could be re-tasked to perform another mission…
Adam Davis
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4 answers

What fraction of 2x2 USA call signs are vanity calls?

I found out a while back that, as things currently stand with the FCC, if you take and pass all three license class exams in the same sitting, you get a so-called "two by two" or 2x2 call -- two letter prefix, region/district number, and two letter…
Zeiss Ikon
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Do lightning rods attract or do they help prevent lightning?

I'd read that the current theory of how lightning rods protect a house, antenna tower, or other structure is by preventing lightning from striking -- that is, the sharply pointed rod lets charge dissipate from the structure, so that it doesn't build…
Zeiss Ikon
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How would I calculate antenna gain?

The concept of antenna gain is pretty important for calculation of link budget and is something I've had contact with. I know that it tells me how focused the waves emitted by the antenna are and I know how to read antenna gain charts. What I don't…
AndrejaKo
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Is the bandwidth of an LCR resonant circuit independent of the capacitance?

Is the bandwidth of an LCR resonant circuit independent of the capacitance, if the inductance and its series resistance are kept the same, and the Q is high? This question and the calculation associated with it were originally posted by a radio…
Harry Weston
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