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1500 questions
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3 answers

Impedance Matching Different Feedlines

(I promise there will be a question in this wall of text. I'm just giving context.) I've been wanting to try my hand at building my own antenna system for the last few weeks and in doing research, a number of questions came up. In particular,…
Italic_
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Identifying signals in the satellite exclusive band

I have just started playing with SDR so I downloaded the relevant amateur band plan for my location, the UK. Tuning around I found things like POCSAG/FLEX pagers as expected and amateur radio (e.g. FM repeaters) at frequencies matching the band…
David
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Choosing capacitor for high-pass filter with cutoff of about 160 MHz

A strong (100 kW) local FM transmitter causes interference to or overloading of receivers in the VHF/UHF bands. It seems like a single, properly chosen, capacitor could make an effective passive high-pass filter. I would like the filter to pass 200…
Jamie Cox
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3 answers

What is the velocity factor of a wire?

This is Belden 9223. It is a 50-ohm coaxial cable, velocity factor 0.56 This is Belden 8524. It is a 22 AWG hookup wire. No velocity factor in the datasheet. Why does the coax datasheet have a velocity factor, while the hookup wire datasheet…
Phil Frost - W8II
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Why are Amateur Radio operators so obsessed about and hostile towards violation of the rules?

Please don't downvote just for the title, I'm not trolling, and honestly looking for an answer. I'm not directly involved with Amateur Radio, but have friends who are. They're always by the book. The book is right. period. With amateur radio, if you…
user1882
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1 answer

Can I still use my Kenwood TM-281A for normal communications even while I have a TinyTrak4 connected for APRS use?

I am considering buying a Byonics TinyTraK4 to connect to my Kenwood TM-281a to do APRS. However, I am wondering if I should instead buy a separate radio (I am considering a Baofeng UV-5R) as well and connect the TT4 to it instead of the TM-281A. My…
W8AWT
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Effect of night on VHF/UHF propagation

I have had some conflicting experiences relating to the effect of night time (ionosphere, temperature, etc.) on propagation. Perhaps it is related to the frequency of what I was working with. Several years ago I troubleshot a Wi-Fi network in the…
Ken - Enough about Monica
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Turning a microwave oven into a transmitter

I know this sounds dangerous and crazy, but those microwave transceivers like the IC-905 are expensive. So, I was wondering if I could make a microwave transceiver with a microwave. You can buy 1200-watt microwaves for under $300. The 1200 watts is…
John Doe
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Will 2 ferrite beads taped side by side perform the same as a single-piece binocular core?

I intend to make a beverage antenna and have quite a few spare ferrite beads of various mixes. If you look up binocular core ferrite on amazon you will see they are a single chunk piece of ferrite with 2 holes side by side bored through it. Is there…
BBQ-Man
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What protocol or API does WebSDR use to stream audio?

What documented protocol or API does WebSDR use to stream audio over the internet? I'm interested in capturing a WebSDR audio stream using a small embedded device which has lots of audio DSP capability, good internet access (TCP/UDP network…
hotpaw2
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Why do homebrew designs wrap toroids instead of using off the shelf inductors?

Why do homebrew designs wrap toroids instead of using off the shelf inductors? Off the shelf inductors are easily available in a range of values, including uH and even some mH. And hand wrapping toroids is laborious and in some cases difficult. …
SRobertJames
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What is an undulator (as used for CW)?

There are historical references to a device called an "undulator" used for CW reception circa before and during WWII. What is an Undulator (as used for CW recording)? How did they work (electronic or mechanical)? Why were undulators used for…
hotpaw2
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Why do 9:1 ununs use type 2 material for the core?

I do not understand how a 9:1 unun wound on a T200-2 works. I understand the transformer voltage and current ratios. I have wound several toroid chokes and 49:1 ununs and know how they work. What is throwing me is that all designs I see use type 2…
user23405
6
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1 answer

Why not access the AO-91 satellite at night during eclipse?

According to amsat-uk.org, the AO 91 satellite should not be accessed during eclipse because it is near EOL. AO-91 (RadFxSat / Fox-1B) Near end of life. If you find it on, do not attempt to access in eclipse! (That is, don't use it at night) I'm…
KJ7LNW
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License problem in Spain

I am from the UK and live in the Canary Islands. I am told I have to take my ham radio license test in Spanish, but I don't speak Spanish. Is there a way around this somehow? Maybe take the UK one (online) or another one in an English speaking…
Stewart Astley
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