Amateur Radio Stack Exchange
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1500 questions
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Looking for a model or description of an EME channel

I am looking for any technical/scientifical/specialized reference describing in some detail the moonbounce for VHF/low UHF frequencies. More precisely, I would be interested in a paper or publication describing some aspects such as the dispersion…
user3141592
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Can coax be run through the center of a radiating element without currents being induced on the coax shield?

I run a λ/2 vertical dipole for 20M that's fed to a 1.5:1 balun at its center with coax that is perpendicular to the dipole (parallel to the ground), for about 30 feet before it comes down to the shack. I wanted some opinions about what would…
Louis Seaman
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LOS One-way radio system, 4km with at least 1000bytes/s

In order to track skydivers/BASE-jumpers with flysight I am looking for a one-way radio system to transmit the location data. System needs the following specifications: Frequency: Not important, preferable legal (Europe) Bandwidth …
wittrup
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CHIRP on Mac in 2021

Has anybody had success in running CHIRP on a modern Mac? I am running OSX 10.15.7 and the download I found for Mac looks like just source code, no app file at all. I'm considering trying a build from source code, but before I get into that let me…
Randy L
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MF band mixer - feasible parameters

Trying to build an homebrew receiver for MF band broadcast (Navtext). Usually working on VHF, where all parts are easily found as an IC, but here I'm trying to get back to roots, so I may be missing something. I'm considering a superhet schema and…
gusto2
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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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How does a loopstick antenna actually receive signal?

Around 1970, I acquired a little transistor radio (powered by 4xAA cells, 6V) that had no external antenna. Inside the back panel (which opened to allow replacing the battery cells) one could see the loopstick antenna, just a ferrite rod with a lot…
Zeiss Ikon
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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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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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