Amateur Radio Stack Exchange
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1500 questions
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Digital transmission sounds

I'm playing with an RTL-SDR dongle and an LNA, on Linux Mint with GQRX and DSD A lot of frequencies show digital transmissions, which the DSD is not converting. I don't whether it is a format DSD cannot convert, encrypted, or just distorted. Is…
KP4MCG
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Soldering PL-259.. with a torch?

I came across this article about torch soldering PL-259 coax connectors. It seemed like a good idea since the body needs a lot of heat to get solder to flow into the holes. It's a little vague when describing the soldering technique for soldering…
Paul
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How can I calculate current distribution on an end-fed dipole antenna in theory?

I understand that in a half-wave center-fed antenna current distribution has a sinusoidal wave approximately, so the current in the center has max value and it has to become zero at the ends of dipole which are open. But since we change the feed…
M.D
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Are there reasons why a receive-only wire antenna should not be λ/2 in length?

The answers to this question explain why it's difficult to transfer power from a transmitter to an antenna that is λ/2 in length (or a multiple for long wires, or as half a dipole's length). Are there reasons why this length would not work or be…
hotpaw2
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Frequency Modulated Light

I've been doing a bit of work on optical open-air transmission, and have been thinking, any hays that varies the intensity of the light or whatever else would affect the amplitude. Would it be possible to send and receive a frequency modulated…
Skyler 440
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Yagi vs Parabolic Dish for 2.4GHz Campus Wifi from 1,800ft away?

My apt balcony is 1,812 feet exactly from my campus's Wifi access point behind a triple pane, brick, 4th floor building window. There is a clear line of sight. I was interested in seeing if I could use a Yagi or a Dish to connect to it. I ran this…
Gabriel Fair
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How to find something disrupting car key fobs across a parking lot?

Apparently there's a parking lot in which car key fobs are messing up: Key fobs that suddenly won't unlock vehicles. Cars that won't start. Alarms that go off for no reason and can't be quieted. Something mysterious is thwarting drivers outside a…
Nat
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How did the terms like QRZ, QTH, and other forms of ham shorthand evolve?

I've wondered if many of the abbreviations are empty, or if they are similar to the recursive acronym like PHP and GNU. For instance, I learned that CQ mimics the two syllables of a French word for Cequite, which means to secure. So, what does QRZ,…
HeavenlyHarmony
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What additional information do I get from an RF ammeter, as compared to a regular SWR/wattmeter?

I've grown up using SWR/power meters. They're "simple" devices: They show forward and reverse power, and show the standing wave ratio. They, however, do not show antenna efficiency. New hams are traditionally instructed to tune their antennas so as…
AndrejaKo
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Best QRP HF band for small antenna?

What HF bands, times of day and/or conditions might be best for attempting to make non-local contacts using QRP transmitter power (around 1 Watt) and a small indoor folded or loop antenna?
hotpaw2
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How to create a simple 1296MHz transmitter?

I have asked this quesion on other sites, but want to try to repeat it here. Also I have asked question about multiplier, and this is a different question. I discovered a 1296MHz beacon in my city that I can receive with SDR and got inspired by this…
Hose Dias
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Share wide band antenna with multiple transceivers

I'm trying to incorporate several transceivers on my board design; I need WiFi (2.4 GHz) SatCom (~1.6 GHz) RF (~900 MHz) and GNSS (~1.5 GHz). I need to combine them into one antenna. I found a wide band antenna that can handle the 700 MHz to 5…
Jedi Engineer
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How to model passive elements when simulating an antenna?

So I started writing an antenna simulator program to design antennas for my needs. To calculate the electric field vector at every point, I split the active element of the antenna into a large number of smaller parts and the calculate the electric…
atomd
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Unlicensed TV broadcasting power limit (Band I)

I'm curious what is the legal limit for unlicensed TV signals being transmitted on the VHF Band I? This seems ill defined. The part 15 FM rules I am assuming don't apply here. And I don't think it can be illegal at all power levels because even old…
Synaps3
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How to interrupt a long discussion on HF politely?

In my city there is a local amateur radio "club". People gather every morning on 7.135 and chat. I was invited by one of the members of this club to join. Turned out that people can chat on this frequency for a very long time without any pauses or…
Aleksander Alekseev - R2AUK
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