Amateur Radio Stack Exchange
Amateur Radio Stack Exchange

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1500 questions
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1 answer

Is calling the Palmer Station (Antarctica) via IRLP without prior arrangements acceptable practice?

Until I can get an HF rig, I've been using my HT through a local repeater IRLP node. I've successfully made a few contacts doing that, but I recently noticed that Palmer Station in Antartica has an IRLP Node (#8838) listed. I tried making a contact,…
penguin359
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Would it be possible for a software-defined FM receiver to demodulate two signals on the same frequency?

When two FM signals are transmitted on the same (or about the same) center frequency, either you hear only one or you hear that noise I'm sure most of you have heard. Would it be possible for a software-defined receiver to track both signals and…
Someone
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What is a fixed digital message forwarding system?

What is a fixed digital message forwarding system? I noticed this on the lower end of the 222MHz allocation in the US but it's not explained on the band chart:
Adam Davis
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What is the best time of day/Band to make a contact with Hawaii from the East Coast?

I need to get Hawaii for Worked All States, and live on the East Coast (Virginia). Furthermore, I have a poor antenna, and thus only the prime times of the day seem to really be opened for me. What time of day/band is the best to make the QSO?
PearsonArtPhoto
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How to Evaluate Antenna Data

I found some data on antennas that had been tested for a specific radio. I'm trying to decipher what this data means and how one would go about gathering it. Are there any good resource for learning how to read and understand this…
Dan
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7 answers

How does IQ modulation work (intuitively)?

I'm trying to get my head around IQ modulation. What I understand so far is that each of the I and Q branches of the mixer produce two sidebands with the same frequency components, but in the Q branch, these sidebands have opposite phase to each…
John B
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What is the appropriate length of an antenna for a handheld on 2 meters?

I want to upgrade the stock antenna on my Baofeng uv-5r for which I mostly use the 2 meter band. The quarter wavelength for this band is about 19.2 inches, but when I look for antennas, they are typically 15.6 or 7.5, or some other seemingly random…
Ryan J.
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Am I really receiving FT8 signals from 12,000 km away on 144 MHz?

I have been using an Ettus B200 SDR to receive FT8 transmissions in the 2-meter band (144.174 MHz) using the WSJT-X software. Signals are received using a telescopic antenna inside on a window ledge with approximately 1 m of cable. I have made no…
David
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What kind of antenna has a spiral connected to a reflector like this picture?

The description on the antenna says it is used for satellite communication, but it was taken in 1984. Is this an antenna style that is still in use? What is it called? What kind of gain should be expected? Is this a style used primarily or only for…
Jason Petrilla
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How does a "chip antenna" work?

How does a tiny surface-mount "chip antenna" for the 2.x thru 5.x GHz frequency bands work? What allows such a tiny item to radiate or receive RF with some amount of efficiency? What allows a chip antenna's radiation pattern to be (somewhat?)…
hotpaw2
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Why is my diplexer such a spectacular failure?

I'm trying to create a diplexer for the 2m and 70cm bands so that two antennas can share a feedline to my "shack". My radio is a Yaesu FT60 handheld, 5W max. I have home made a j-pole for 2m, and a neat little ground plane antenna for 70cm, both of…
user14945
10
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2 answers

How can I calibrate a SWR meter?

I would like to build my own HF (1.8 - 30 MHz) SWR meter, however I'm not sure how I can calibrate the meter without an accurate power source. I'm targeting a power capacity of 150 W so I can use it with my HF radio. However, my test equipment at…
W5VO
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Is it legal for a non-profit to use ham radios for emergency purposes?

I've been tasked to help update my organization's emergency contingencies and ham radios were brought up. We provide residential services to the mentally handicapped and we are looking at ways to make sure the staffed houses can talk to each other…
Michael Ramirez
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I can copy 15wpm how to to continue?

I solely learned to copy cw via a computer program using the Koch - method (http://f6dqm.free.fr/soft/cwplayer/en/cwplayer.htm) I never learned how to send and if it is no big disadvantage, I would prefer to learn this at the end, when I am…
03525
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Can a 1:1 transformer be used as a protection from static electricity?

It's well-known that under certain conditions verticals and dipoles can gather static charge, which is a common reason of transceiver damage. There are several ways to solve this issue. Some hams suggest to place a 100 kΩ high-power resistor to the…
Aleksander Alekseev - R2AUK
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