Newest Questions
4,999 questions
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What is the input voltage of a typical 2.4 GHz WiFi antenna used at home?
I am trying to find the input voltage to a 2.4 GHz antenna used in a typical WiFi modem at home. Basically, I would say I want to disconnect the antenna from the modem and measure the voltage. I am ...
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1
vote
1
answer
100
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Finding phase center of antenna simulated with 4nec2
I am trying to simulate a helical antenna for 1.7GHz and would like to extract the phase centre so I can correctly mount it at the focal point of my dish.
But I do not know where to find this or how ...
- 165
1
vote
2
answers
186
views
Why this dipole antenna has 75$\Omega$ to 300$\Omega$ matching network in it?
I have bought this antenna in the thrift market.
It seemingly is a dipole for FM radio bands - both telescopic arms extend around 1.5m total. But it is connected in a strange way - in the connector ...
- 151
3
votes
1
answer
160
views
Tuned IF amplifier saturation
I was designing a tuned IF amplifier. I went with a staged Amplifier design with freqeuncy of 10Mhz. While reading through different sources, i found out that we get about max 5mV amplitude from an ...
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1
vote
4
answers
182
views
Making antenna elements with copper wire lashed to a steel rod
For making stealthy antennas with rigid elements, I want the elements to be thin but stiff. Steel is stiff and is a conductor, but not a great one. I was wondering about using thin steel rod (say 1/8 ...
- 501
1
vote
0
answers
135
views
JS8Call sound input errors when using USB as DATA MOD setting, but not when using ACC as DATA MOD setting for Icom IC-7300
I recently purchased an IC-7300 shortly after receiving my general license.
In trying out JS8Call, I discovered that when setting the radio to data mode, and ensuring the input is set to USB, I ...
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2
votes
1
answer
143
views
AM radio over rainforest
Where to find information about the AM radio reception at tropical rainforest environment?
Here in Colombia exists the more humid environment of the planet.
I can't find information about am radio ...
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0
votes
1
answer
83
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How noisy are EcoFlow battery backup and power station products in HF?
I'm thinking about replacing some near-EOL UPSs with EcoFlow products (for one thing, they use LiFePo4 instead of lead/acid and so are smaller and lighter) but before doing so I was wondering if ...
- 1,089
1
vote
1
answer
160
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Adding a choke to the feed point
I recently installed a vertical antenna and was surprised by the loud noise. I am thinking of adding a choke to the feed point, but is it sufficient to simply add one? Or should I adjust the antenna ...
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0
votes
1
answer
75
views
Using Allstar's web transceiver function
I am trying to connect to a repeater with Allstar but this is what I get:
There is nothing underneath the label. I read a PDF that says you needed to use a browser that supports Java, so I went with ...
- 797
3
votes
1
answer
117
views
How did telegraph operators ensure they received the intended message? Was some sort of checksum used?
Assuming the operators were using Morse code (un-encrypted or otherwise) how could the receiver determine they got the correct message?
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4
votes
2
answers
321
views
Discrete-Component Mixer design
I was building a radio receiver for FM waves (87.5-108MHz), I want to build every block on my own (oscillators, mixers, demodulators) and then put them together.
I was now designing a mixer and i ...
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5
votes
4
answers
2k
views
Can I float an SLA 12v battery at 13.8V forever?
I am considering a battery-backup power source for a radio. Typically, power would be supplied through a standard 13.8V power supply, so the battery would be available if mains power goes out:
...
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4
votes
3
answers
2k
views
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-...
- 797
2
votes
2
answers
312
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Considerations for UK / USA operation
I'm just getting into this. I'm currently based in the US and am studying for my ARRL Technician exam. I'd like to start listening in, so I'm in the market for my first radio.
One wrinkle in that I'm ...
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