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1500 questions
10
votes
3 answers
What is the actual loss in a feed line with high SWR?
It is well-known that it is unwise to have standing waves on the feed line between one's antenna and one's transmitter, unless it is a very low-loss type (e.g. ladder line), because the transmitted signal is reflected multiple times through the feed…
Kevin Reid AG6YO
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10
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2 answers
What determines power handling capacity of an antenna?
I just bought a cheap 1/4-wavelength, 2m. mag-mount antenna. The package says it can handle 50 watts. I can think of three things that could limit the capacity:
$I^2R$ losses in the connection to the feedpoint and in the antenna wire itself:…
Pete NU9W
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10
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2 answers
Moon->Earth 433MHz link achievable digital bandwidth
Let's assume we have the following situation:
Transmitter on moon orbit (distance from earth ~400'000km), around 433Mhz.
Transmitter power 1W, antenna gain 10dB, circular polarization. Steered to point to earth.
Receiver is on Earth. Antenna is…
BarsMonster - R2AYN
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10
votes
2 answers
Where on the web can I find a calendar of upcoming contests?
For years, I have been using SM3CER Contest Service for HF contests.
It is always good to have a backup, so I am looking for more or better.
What do you recommend?
on4aa
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10
votes
1 answer
What is emissions designator "E" when used as a type of modulation?
The FCC's rules regulating amateur radio, in 47 CFR 97.307(f), paragraph 8 defines one emissions standard/limitation as follows:
A RTTY or data emission having designators with A, B, C, D, E, F, G, H, J or R as the first symbol; 1, 2, 7, 9 or X as…
natevw - AF7TB
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10
votes
4 answers
How to operate on HF if an AM transmitter is only 540 feet away?
I'm a General Class Licensee, and due to pulmonary disease I cannot operate voice. I am also about 540 feet from a 24/7 1 kW AM station. The signal is so pronounced that most audio devices in the house pick up the station. Every shortwave receiver…
Gordon C
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10
votes
1 answer
Why do we use decibels in radio?
We can measure power in watts, and gain or loss in unitless ratios. So why bother using decibels for these things?
Phil Frost - W8II
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10
votes
4 answers
Is use of the phonetic alphabet mandatory?
The phonetic alphabet is often used on amateur radio to spell out names and callsigns more clearly, especially when the clarity may be poorer. However, there are cases where I simply forget certain parts of this - in this case, is it ok just to use…
berry120
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10
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1 answer
What's the difference between "maximum usable" and "critical" frequencies?
In discussing HF ionospheric propagation, you hear about both "critical" and "maximum usable" frequencies. For example:
Above the critical frequency, the ionosphere is unable to refract the signal back to Earth and it escapes to space. The critical…
natevw - AF7TB
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10
votes
2 answers
What is a "calling frequency"?
Doing some study for the ham test, I read a question asking about a certain “national calling frequency”.
What is a “calling frequency”?
What is meant by “calling” in this instance?
SunSparc
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10
votes
1 answer
Faraday cage in Microwave oven
If I put my mobile phone in my microwave oven and close its door,
Should I be able to get incoming calls ?
Because, I tried it and I was able to get calls, what does it mean?
Does my microwave oven has a radiation leak?
volatile
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10
votes
1 answer
Is there a name for the demodulation technique described here using the parallax propeller?
Is this a recognized SDR technique with a name, or is just a combination of DSP, r/f techniques ?
I asked the author, but didn't receive an answer, perhaps because he thought it was "obvious" (not to me, though, an SDR / electronics…
mstram
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10
votes
3 answers
Is Using PMR446 On A Baofeng GT3-MK3 HAM Radio Legal (If on low power)?
I have a Baofeng GT3-MK3, a great little radio.
Is it OK to use this on the low output setting for general use without a licence, for things like camping/hiking family use etc, if I used the legal frequencies, i.e. 446 in UK?
Jucks
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10
votes
5 answers
What is the highest US amateur license I can get in one sitting?
If I start with no current license, can I take all the exams in one sitting to get to Amateur Extra?
nzc
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10
votes
2 answers
Can every antenna be used both for transmit and receive?
Assuming I have an antenna for receiving GPS signals, can I use it also for transmit — to create a repeater in a tunnel (or some place with no reception)?
volatile
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