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1500 questions
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Why are loopstick ferrite antennas commonly wound with Litz wire?
What is the advantage of using Litz wire to wind ferrite (loopstick) antennas? How much of an advantage in what characteristic does this type of wire provide? (over generic single strand enameled or insulated wire). How do different types of Litz…
hotpaw2
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Measurement of antenna with VNA does not match its specs
I have a NanoVNA V2 Plus (50kHz - 3GHz) and decided to test my LoRa antennas:
an unknown antenna delivered with a LoRaWAN gateway (RAK831)
a 868Mhz antenna from Linx Technologies (ANT-868-OC-LG-RPS)
As the range was poor between my gateway and my…
DurandA
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Choosing a Relay for HF Applications
As part of my 20m transceiver build I'm looking for a relay to by-pass an RF amplifier in the front-end board. So, to be clear, that's after the 20m broad bandpass filter and before the RF mixer (it's a single-conversion superhet design).
Being the…
Buck8pe
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Are there any cons of running shack on battery?
I'm building a low-power shack to operate on non-licensed bands (UHF PMR 0.5W + HF CB 4W). I don't have any "RF-grade" sources of 12(-ish) volts and don't want to buy a specialised power unit.
I'm thinking of running the whole setup from a 12V…
Alexander
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3 answers
When a dipole antenna is fed via coax, what powers the ground-side of the dipole?
I've been trying to understand how dipole antennas work, and I believe I understand the basics when they're fed via a balanced feed line. In fact, every dipole physics YouTube video and web page I can find explains how they work with a balanced feed…
Asker2093022
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(When) does a transceiver re-reflect 100% of reflected power?
There has been a long discussion of one question here. Phil, W8II and I agreed that it's better to post a separate question.
There are several sources (some editions of "The ARRL Handbook", "Reflections: Transmission Lines and Antennas",…
Aleksander Alekseev - R2AUK
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what is main reason for formation of side lobes in directional antennas?
I would like to know why are side lobes formed along with main beam in an antenna.
I asked one of my colleague and he explained me that its due to radiation of frequencies near to the required center frequency. I'm not sure about this explanation…
Aparna B
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Energy vs power in transmitters
Higher frequencies have a higher energy, simply stated by Planck's constant. When I am transmitting 100 watts on 500 kHz, and transmitting 100 watts on 5 GHz, is there an energy difference in the wave?
Skyler 440
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Acceptable RF radiation exposure to electronic equipment
I'm wondering if there are any general guidelines or rules of thumb about the exposure of electronic equipment to RF transmissions, 150 MHz - 900 MHz.
The background is that we are looking to install an LMR antenna for a 35 to 50 Watt radio above an…
Frank
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What is band stacking?
What is a band stacking register and/or band stacking buttons on a transceiver? And why would this be useful to an amateur radio operator?
Is using "band stacking" a current operating technique, or are there more modern operating methods? (such as…
hotpaw2
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How to compute the required length and turns for an air-cored antenna
I'm experimenting with RF reception in the 433MHz band and have made the most simple "whip" monopole antenna with 17.6 centimeters of wire.
Out of curiosity, I tried various designs for the antenna among which the one described in the step by step…
OBones
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Failing to detect Hydrogen line with 105cm dish
I've seen many examples of roughly 1 metre sized dishes being used w H+ sawbird and an SDR to detect and analyze Hydrogen line signal, and have been trying myself but can't seem to get anything beyond maybe a small whiff. I'm using a 105cm satellite…
Jack_SH
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Consistency of Morse Code/CW sending speed
How important is it to maintain a consistent Morse Code WPM keying speed when transmitting CW? I occasionally hear operators slow way down when sending RST and location info, and then later identifying at double speed from the rest of the QSO. Is…
hotpaw2
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5
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1 answer
How to choose a coaxial cable
How do you know which coaxial cable to choose for your application?
For instance;
I require a cable that has a 50ohm impedance, an operating frequency of 2.4GHz, length of 100mm, and needs to be semi rigid to support the elements of the antenna I…
Ben
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How is the Hackrf able to achieve 20MHz of bandwidth with an ADC that only allows 22Msps?
The way I understand it, is that to avoid aliasing on an ADC, you have to be in the first Nyquist zone (so half the sampling speed). What doesn't make sense to me is how the Hackrf is able to bypass this, and achieve 20MHz of bandwidth, even though…
camerakid
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