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1500 questions
5
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Why does my received power rise so much when I connect an antenna?
I am in early stages of making a narrow-band radio receiver (block diagram below). To give you an idea, I am using a simple CP-FSK based modulation scheme, and have achieved 5dB SNR with a Tx signal of -118 dBm on wires (feeding signal via an R&S…
Kraken
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5
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What is this vertical antenna with radials pointing up
I work next to "Koninklijk Marine Kadettenkorps Afdeling Oostende" (Royal Marine Cadet Corps Ostend). They have an antenna that I've been wondering about for years now:
It is a vertical antenna, likely HF bands with four radials angled about 45…
Dieter Vansteenwegen ON4DD
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How does single sideband work theoretically?
How does single-sideband (SSB) work theoretically? If a theoretical SSB transceiver is a "black box" and only its inputs and outputs can be analyzed, not the way it works internally, what is happening?
kj7rrv
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Why did the International Telecommunications Union denote CY for Canada?
CGP Grey recently released a video on the history of airport acronyms, e.g., LAX. He briefly said that you may wonder why codes for Canada started with Y and formerly CY, and that it traced its history to the telegram “but that’s a story for another…
Ethan Miller
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5
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2 answers
How can AM radio work differently when approaching the true frequency from different directions?
I bought a very cheap world band receiver, Nedis RDWR1000GY. It has MW, SW and FM reception. MW is useless where I live (no MW stations nearby and signals don't propagate far), but I was primarily interested in the SW and FM reception. The FM…
juhist
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5 answers
Is FM effectively spread spectrum?
My understanding is that FM achieves better audio quality (under the right circumstances) than AM by spreading the narrow audio signal's information into a wider RF signal. Does this mean FM is technically a form of spread spectrum?
Someone
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5
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UHF 70cm unlicensed use
We are farmers with (edit) 25-40w radios mostly old Kenwoods and Motorolas in all of our tractors and vehicles. I'm not exactly sure what frequency we have but the man who programmed them set them up with 2 preset channels. We are not licensed hams.…
Logan
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4 answers
How can I inject an oscillator output into the RF input to my radio?
I have a Bodnar GPS disciplined oscillator, and I would like to inject its output into the antenna input to my HF rig. This will allow me to compare the frequency of received unknown signals to the highly accurate Bodnar signal. There are a couple…
Bill KG5RMJ
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5
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3 answers
does the shape of an antenna ground plane matter?
I would like to test a tranceiver setup I created before I mount it in my car. In my backyard, there's a length strip of metal; 10m in length, 10cm wide. Now I wonder if I can use that as a ground plane for an antenna.
Is it important for an antenna…
Folkert van Heusden
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Why do so many hams prominently display their callsign in the shack?
By ham standards, I'm far from being a long-time adept of amateur radio, but I've seen my fair share of shacks, both on the internet and in person.
What's always attracted my attention is that almost every one of them has some sort of platter with…
Ivan R2AZR
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3 answers
How are capital letters sent in Morse code?
There is only one alphabet in Morse code, so is there a recognised way to indicate a capital letter?
Harry Weston
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5
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3 answers
Do I need a precision wattmeter or will a $50 one suffice?
My transceiver has a built-in wattmeter but I've decided to buy an outboard one to monitor the antenna system before it reaches the ATU. I'm capable of putting out 100 Watts and I see that several manufacturers offer meters in the $50 range that…
Dax
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How to play spectrum recordings made with rtl_sdr in gqrx?
I have an R820T DVB dongle and the rtl_sdr software on a linux computer.
I can listen to various frequencies using the gqrx software which uses the rtl_sdr library as a device driver for the USB-attached dongle. I also (obviously) get the spectrum…
Paul
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5
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How do antennas over 1/2 wavelength work?
I've been told countless times that an antenna should be 1/4, or 1/2 wavelength. That increasing this size to a higher multiple of 1/4 will work, but it will distort the radiation pattern to include several high gain lobes shooting energy off in…
Dportology
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5
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2 answers
What happens if I “open” a folded dipole so that the two wires are not connected anymore?
A folded half wave dipole consists of two wires in parallel with only one of the wires driven, but the ends of the two wires electrically connected. As I understand it (and I may well be wrong there) the folded dipole still behaves similarly to a…
anyfoo
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