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1500 questions
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2 answers
Yagi vs Parabolic Dish for 2.4GHz Campus Wifi from 1,800ft away?
My apt balcony is 1,812 feet exactly from my campus's Wifi access point behind a triple pane, brick, 4th floor building window. There is a clear line of sight. I was interested in seeing if I could use a Yagi or a Dish to connect to it.
I ran this…
Gabriel Fair
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1 answer
How to find something disrupting car key fobs across a parking lot?
Apparently there's a parking lot in which car key fobs are messing up:
Key fobs that suddenly won't unlock vehicles. Cars that won't start. Alarms that go off for no reason and can't be quieted. Something mysterious is thwarting drivers outside a…
Nat
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How did the terms like QRZ, QTH, and other forms of ham shorthand evolve?
I've wondered if many of the abbreviations are empty, or if they are similar to the recursive acronym like PHP and GNU. For instance, I learned that CQ mimics the two syllables of a French word for Cequite, which means to secure. So, what does QRZ,…
The Harmonic Rainbow
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5
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2 answers
What additional information do I get from an RF ammeter, as compared to a regular SWR/wattmeter?
I've grown up using SWR/power meters. They're "simple" devices: They show forward and reverse power, and show the standing wave ratio. They, however, do not show antenna efficiency. New hams are traditionally instructed to tune their antennas so as…
AndrejaKo
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5
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2 answers
Best QRP HF band for small antenna?
What HF bands, times of day and/or conditions might be best for attempting to make non-local contacts using QRP transmitter power (around 1 Watt) and a small indoor folded or loop antenna?
hotpaw2
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5
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1 answer
How to create a simple 1296MHz transmitter?
I have asked this quesion on other sites, but want to try to repeat it here. Also I have asked question about multiplier, and this is a different question.
I discovered a 1296MHz beacon in my city that I can receive with SDR and got inspired by this…
Hose Dias
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5
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2 answers
Share wide band antenna with multiple transceivers
I'm trying to incorporate several transceivers on my board design; I need
WiFi (2.4 GHz)
SatCom (~1.6 GHz)
RF (~900 MHz) and
GNSS (~1.5 GHz).
I need to combine them into one antenna. I found a wide band antenna that can handle the 700 MHz to 5…
Jedi Engineer
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5
votes
1 answer
How to model passive elements when simulating an antenna?
So I started writing an antenna simulator program to design antennas for my needs.
To calculate the electric field vector at every point, I split the active element of the antenna into a large number of smaller parts and the calculate the electric…
atomd
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5
votes
3 answers
Unlicensed TV broadcasting power limit (Band I)
I'm curious what is the legal limit for unlicensed TV signals being transmitted on the VHF Band I?
This seems ill defined. The part 15 FM rules I am assuming don't apply here. And I don't think it can be illegal at all power levels because even old…
Synaps3
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1 answer
How to interrupt a long discussion on HF politely?
In my city there is a local amateur radio "club". People gather every morning on 7.135 and chat. I was invited by one of the members of this club to join. Turned out that people can chat on this frequency for a very long time without any pauses or…
Aleksander Alekseev - R2AUK
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5
votes
2 answers
What is the frequency range 2300-21950 kHz used for?
I was checking out the gizmo mentioned in this question, and I see that it can receive "shortwave" in the frequency range 2300-21950 kHz. Most times I see "shortwave" mentioned, it's by sales or nontechnical people to describe any number of things.…
YetAnotherRandomUser
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1 answer
Why were "PARIS" and "CODEX" considered "typical words"?
In the context of wondering how to convert characters per minute to words per minute, it was pointed out that CODEX and PARIS are used as typical words for measuring speed of CW operators.
As the wikipedia states:
There are two common typical…
Marcus Müller
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5
votes
3 answers
How can I determine/measure power rating of a DIY air capacitor?
I've build an air capacitor like the one described in this article, although I used 1 mm thick single side copper boards (FR4) instead of solid copper sheets. I would like to use such capacitors in my next projects, e.g. an antenna tuner and a…
Aleksander Alekseev - R2AUK
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5
votes
3 answers
Are there any good, consistently receivable signals in the US for HF receiver testing?
Having built my first HF receiver, I'd like to know if I'll need to search around for transmissions that happen to be occurring, or if there are reasonably strong signals I can count on being present regardless of the time or day? I just want a…
Adam Davis
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5
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Why are the lower HF frequencies not working during winter day time?
Currently my location is Nepal. We use the ICOM f-7000 radios without the antenna tuner. We use the frequencies round about 5-9 MHz, for communication over distances between 150 and 400 km.
During the summer time during the day the radio works fine…
Angry Hooman
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