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1500 questions
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3 answers

How can I reduce the noise coming in from an RTL-SDR dongle?

I've recently received an RTL-SDR dongle, and I'm picking up a lot of noise that is probably coming from my PC, especially a lot of "spikes" on the 2M band. I've already started using a USB extension cable instead of plugging the dongle into the PC.…
krzysz00 KF5SOQ
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High 40m noise floor during the evening but quiet in the afternoon

I've been dealing with S7 static on 40 meters ever since I got started a few weeks ago. It's so bad that I have to use my RF ATT so that the static is not deafening. I did some research about finding noise sources (mostly wall warts) and common…
Paul
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How might one realize a first order, two dimensional RF field antenna for HF?

I just coined the term "field antenna". It is by analogy to the lightfield camera or the soundfield microphone. Essentially, it is an antenna that captures not only the strength of an RF field, but also the direction of it. Of course, these antennas…
Phil Frost - W8II
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Is a multiple-wavelengths antenna possible in UHF and up?

I know that in the High Frequency regions of the ham bands, the antennas have to be sub-wavelength because most people just can't put up a 160 meter full-size antenna. Let's say we're in the 23 centimeter or an even higher band. Can the antenna…
Skyler 440
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Are there ways for people with receivers to participate in contests?

At the moment I only have an HF receiver (or I will when I build it, hopefully soon). Are there any contests I can participate in, or ways for me to participate in a contest without borrowing a transmitter or working with an amateur who has one?
Adam Davis
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Is there a simple, DIY, antenna suitable for HF receive only?

So the antenna I'm thinking about doing might be* way too large for my property. Is there another simple, cheap, DIY antenna I could try on my receiver? I know I'm going to want to hook it up and have a listen before the last solder joint has…
Adam Davis
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How Could Superheterodyne Receiver Ever Work?

I am surprised how the Superheterodyne Receiver still works and is still in use after coming to realise the impact of Image Frequencies on its performance. Basically, I'm curious how engineers make such an architecture work despite the affect made…
Denis
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What are the I and Q in quadrature sampling?

For some reason I've long believed that given I and Q, one corresponds to amplitude, and one to phase, so I thought that I could hold one steady and create AM, or hold the other steady and create FM. Now that I'm delving more into it, though, it…
Adam Davis
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Rolling QRM from 3000-10000 kHz - What Is It?

Video I was lucky to catch the QRM start this morning @ approximately 10 AM Pacific Standard time. It was wide, starting around 3000 kHz up to 10000 kHz. It starts fast then slows to a crawl. The noise has pronounced high/low bumps as you'll see in…
user11702
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Is there a different ham radio phonetic alphabet?

I was reading New Ham Radio License by AG6IF and the author says something strange in the context of station/operator identification: Use the standard ham phonetics, not the Air Force version, or the Fire Department's version or something you heard…
RoboKaren
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What changes are being made to the Technician question pool in 2018?

On 2018 July 1, the FCC's question pool for the Technician class license will be changing. Has anyone written up a summary of the updates or made a list of differences from the previous pool? What are the most significant changes I should be aware…
natevw - AF7TB
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IQ imbalance after quadrature mixing

What is IQ imbalance in the output of complex or quadrature downconverter/demodulator/mixer? What are the causes and effects of IQ imbalance? (A spike in the spectrum display of RF noise?) Are there any SDR algorithms for reducing the negative…
hotpaw2
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What does exclamation mark mean in FT8 CQ calls in WSJT?

For example, in this screenshot: WSJT shows !Italy, !Serbia, !U.S.A. What does it mean?
Pablo Fernandez
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Getting permission from the master of the vessel

I'm crossing the English channel on a ferry soon and I'd like to do some radio while on it. According to my license (full British Ofcom amateur radio license), to be able to do this, I need permission from the master of the vessel. What should…
Pablo Fernandez
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How do I notify and publish information on experimental modes?

I'm considering tinkering with a new mode. Of course I'll stick to experimental channels and low power for now, but as people notice my transmissions they won't immediately understand what is being transmitted. How do I disseminate information that…
Adam Davis
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