Questions tagged [radio]

Consider also the rf tag.

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81 views

Send a video radio signal via a PC to a portable VHF/UHF TV [closed]

I‘m trying to build an art installation. I want to send a video radio signal via my PC to an old portable TV. My idea was it to run a HDMI cable to a D/A converter and run a software that lets me send ...
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0 votes
0 answers
63 views

I am confused about finding the S-parameters with a capacitor or an inductor

I don't know how to solve this problem with the capacitor and inductor. Could anyone please help me?
1 vote
1 answer
76 views

How does one test an AM antenna matching network?

I'm lost. I need to test two AM matching networks. I was not given training and I'm a newborn compared to every other guy in AM Radio out there. I do own a osciloscope with Bode plot generator but I ...
3 votes
3 answers
100 views

Why doesn't RadioHead ASK work on ATtiny84?

Using the RadioHead library (ASK), I was able to get an ATtiny84 to transmit a message to an ESP8266 using a 433MHz transmitter module, but it took a little tweaking with the bit rate (the 1st param ...
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-4 votes
3 answers
115 views

What is the method to mute sound during seek on RDA5807 FM?

How to does noise canceling work on thisRDA5807M FM radio module? What can I do to mute noise on the radio? I want to mute immediately when there is blank white noise on the FM radio.
-1 votes
1 answer
84 views

How or why are powerful but low-frequency radio waves, such as from a radio station or cell tower, potentially dangerous? [closed]

Cell towers / base stations and such are limited in the power they are allowed use, even if the wavelengths of radiation used do not adversely affect people or animals. I have heard (and read) that it ...
2 votes
0 answers
43 views

Transistor impedance

According to LDMOS transistor AFT05MS031N datasheet at p. 13 " ZSource - Test circuit impedance measured from gate to ground" for 155 MHz is Z = 4.31 + j.7.54 https://www.nxp.com/products/...
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1 vote
1 answer
97 views

Is an analog radio tuner more robust in a nuclear blast than a digital tuner?

Some radio receivers seem to have analog tuners (i.e. you turn a knob and it's completely mechanical), whereas others are more digital i.e. they can search for stations, save them as "presets&...
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0 votes
1 answer
67 views

12 VDC to 6 VDC to power a radio [duplicate]

I have a Grundig radio that requires 6 V and 500 mA negative center pin. It is very sensitive to noisy wall warts, so I want to power it from my very noise-free ham radio 12 V power supply. Can I use ...
2 votes
3 answers
108 views

Effect of small length impedance discontinuity in a transmission line

Consider this arrangement of a radio, a long coax cable, a small length of "random" cable and an antenna. The radio, the coax and the antenna all have the same impedance, but the random ...
2 votes
2 answers
120 views

Crystal Radio Troubleshooting

I am learning radio starting with the basics, and I had a question about the behavior of my set up. I made a crude schematic below, the antenna is a 14 AWG random wire that I hung from a tree (using ...
2 votes
1 answer
101 views

Frequency marking on 1960s radio crystal

I found several of these old radio crystals, but they do not seem to have the frequency clearly marked, which I found unusual. Most other ones I have seen have a model number (e.g. CR-18/U) and the ...
1 vote
0 answers
45 views

How do I determine the acceptable delay spread in an analog FM simulcast LMR system?

I'm using a commercial propagation analysis software to analyze a legacy VHF simulcast Land Mobile Radio (LMR) system. I'm trying to analyze the parameter "Delay Spread". The software ...
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8 votes
2 answers
911 views

Radio static due to neighbor's shredder

I live in a condominium apartment building. I have a Bose Wave Radio with a dipole antenna connected. I frequently listen to FM radio stations. One of the stations I listen to has pretty good power ...
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10 votes
3 answers
2k views

Is there a name for this vintage 3-pin connector configuration?

I am trying to find a suitable replacement for this connector for a vintage radio, but I'm not sure how to search for it or if they even sell them anymore. Simply "3 pin male connector" isn'...
0 votes
2 answers
153 views

Why are microwaves unidirectional and radio waves omnidirectional?

I understand that any wave can be given direction using a setup like a phased array. As I read about the properties of EM waves, I find that microwaves are unidirectional in nature. What is it about ...
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0 votes
1 answer
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Can telescopic FM/DAB antenna be replaced by Coax?

I tried to search for this prior to asking but with no luck... I have an FM/DAB+ antenna like this: from which a standard 75-Ohm Coax is coming down and I would like to connect it to the radio (...
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1 vote
1 answer
43 views

What happens to a traveling wave tube amplifier when the amount of available power drops?

The two Voyager spacecraft use traveling wave tube amplifiers to send data back to us. These have 2 power settings: 12W and 18W. The power supply on board the Voyagers (an RTG) produces less power ...
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-1 votes
2 answers
184 views

Please verify tube AM radio transmitter [closed]

I am an electronics hobbyist. I designed this tube AM transmitter circuit. I want to ask you, since it's my first designed circuit, if it will work, and if I can improve it. I am using a PL500 for the ...
1 vote
0 answers
52 views

Clarification on I/Q Mixer output

I'm working on RF Receiver, it is required to use I/Q Mixer for IF downconversion. Specification as follows below ...
0 votes
0 answers
29 views

IQ mixer LSB and USB image rejection and conversion loss

I am trying to test the rejection and conversion loss of the HMC1056LP4BE IQ mixer. I set the LO to be +10dBm @8.5GHz, IF1: -10dBm @250MHz, IF2: -10dBm @250MHz. Here I am using 3 different ports of a ...
0 votes
0 answers
39 views

What is the appropriate name for a parabolic antenna with a "center mounted feed"?

How would a parabolic antenna with a "center mounted feed" be called? Below are some images which illustrate the type of parabolic antenna I'm referring to. According to wikipedia these are ...
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0 votes
0 answers
97 views

Longwave Radio Receiver, Non-SDR Version

It is my understanding that radio receiver designs change drastically once you get into the sub-MHz range (superhet doesn't seem to make a whole lot of sense at this point). I seem to be leaning into ...
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4 votes
3 answers
506 views

DVB reception: Why do I need to add a coaxial cable to my installation to improve SNR of the signal?

I have the following installation: Dipole antenna <------> Coaxial cable (3 m) <-----> DVB receiver If I connect my dipole antenna directly to the DVB receiver, removing the coaxial cable (...
1 vote
1 answer
77 views

Noise factor in homemade software-defined GPS receiver

I'm building a homemade software-defined GPS receiver. I'm currently at a point where I can acquire and track strong signals but struggle to even detect weak signals. I've ruled out problems with my ...
0 votes
2 answers
97 views

Can a LC circuit generate frequencies in the Gigahertz range or higher?

For instance, if you took a bunch of off the shelf capacitors and arranged them in series and a bunch of inductors and arranged them in parallel, could you make the resonant frequency of the LC ...
1 vote
2 answers
134 views

Mechanical buzzer heard on AM radio

If I connect this little mechanical buzzer to a 3V supply, then hold my AM radio close to it with the radio tuned so I can't hear any stations, I can hear the buzzer on the radio. If I turn up the ...
1 vote
2 answers
75 views

Super Low Frequency (SLF) compact receiver

I am looking at options for receiving the 50Hz (UK) mains hum from a nearby substation. The goal is to filter some measurements, so I need to produce pulses in time with the zero crossing (or peak). ...
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0 votes
0 answers
32 views

Field cancellation of small antennas nearby

For example, two loop antennas in the same plane, but current in them is in anti phase. So that when viewed from afar field cancels out. How can I calculate effect of this cancellation? I expect it to ...
1 vote
3 answers
134 views

Why is my best placement of a directional antenna so weird?

I moved to an offgrid house with a 3G/4G repeater, with a short, enclosed directional antenna. It was wobbling and poorly mounted on an unstable wood plank at the base of a window, so I decided to ...
0 votes
1 answer
78 views

Ideas for charging 12v battery

I’m a 17 year old in high school, and for my class project I’m making a cooler with a car radio, and car speakers built in which is being ran off a 12 V battery. It works just fine but I have people ...
1 vote
1 answer
89 views

Is there any electrical system simple enough to make yourself which has some kind of useful property like radio communication or basic computation? [closed]

I would like to make some kind of primitive system in the direction of a computer, from scratch. Someone showed me you can use ferromagnets to do some elementary computation; the “states” are the ...
0 votes
1 answer
192 views

What exactly is this piece of electronics?

I've come across a component which I have not been able to find on Google. My guess is that it could be a sort of radio controller, since I recognise an antenna and a 27M oscillator. I have included ...
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0 votes
2 answers
80 views

Buying a variable inductor

I need a variable inductor of about 70 nH. I found one at Mouser. As you can see, it says that its inductance is 70 nH, but when I open the datasheet it says that inductance is from 9 to over 280 nH. ...
0 votes
0 answers
96 views

What is this device? (from historical photo)

Anybody know what this might be? It's from an old photo with my grandfather as a teenager who went on to work on radar during the war and later for "His Masters Voice" repairing televisions. ...
-1 votes
1 answer
51 views

Why does short band (high frequency) radio travel longer than low frequency?

In physics, we are taught that longer wavelength (lower frequency) have a lower attenuation in air, and thus is able to travel longer distances. However, when talking about radio channels, short wave (...
2 votes
1 answer
96 views

nRF24L01+ Doesn't Receive Packets

I am trying to send data from one MSP430 to another MSP430 using Nordic Semiconductor nRF24L01+ radios, but I am unable to receive transmitted packets. I am able to read from and write to the radio ...
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0 votes
0 answers
66 views

Best antenna design with the following requirements?

I'm looking for the best antenna design with the following requirements Small Discrete Wideband (LTE and WiFi) Directional High gain (20-25dBi with relatively high transmission power) Could anyone ...
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8 votes
2 answers
2k views

Is AM radio louder the closer you are to the transmitter?

Following on from this question, does the volume of the receiver increase the closer it is to the transmitter because it's receiving more of the radio signal? This question specifically is for a ...
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0 votes
3 answers
142 views

Problem in the book "Radio Antennas and Propagation"

I came across a problem in an electronics textbook by William Gosling, Radio Antennas and Propagation. I am an undergraduate and I sent this to my lecturer to help solve but unfortunately, her answer ...
4 votes
1 answer
356 views

What does this capacitor do?

Preface: I am not an EE and just a hobbyist. I designed this FM radio circuit and it works as shown. My Question: When C4 was originally, 1nF, there was no output on C2. Once I experimentally picked a ...
2 votes
2 answers
93 views

Splitting CB Radio Mic Inputs?

I just purchased my first CB radio and I am looking to split the microphone's output such that it can go to two outputs (the radio itself and custom electronics I plan to design). I'm using the Uniden ...
2 votes
1 answer
104 views

VHF Amplifier Design

I am an RF enthusiast that wants to learn how to think like an engineer. I am trying to build a FM receiver that consists of a wideband FM amplifier and a slope detector. I have so far created an ...
0 votes
3 answers
89 views

Can an RC receiver antenna work for an ESP8266?

I will be building a project that uses an ESP8285 based ESP01F board (kind of ESP8266) and I need an antenna for this module. The antenna I need should be very light and thin so I thought of using an ...
0 votes
2 answers
95 views

Do RF amplifiers increase range bidirectionally?

I read an article where they set up a incredibly high power, high gain WiFi antenna (https://hackaday.com/2016/10/15/a-lot-of-wifi-power-a-yagi-and-a-snipers-scope/). He uses an RF amplifier in order ...
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1 vote
1 answer
77 views

RF direction finding

Is it possible to build a system of antennas to find the rough direction of a radio frequency emitter such as a WiFi router, a Bluetouth tag, or, a 5G cell tower? I cannot use distant antennas to use ...
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33 votes
1 answer
3k views

How did 455 kHz end up being a commonly used IF (intermediate frequency)?

Of all possible IF frequencies, why did so many consumer radio and amateur HF radio manufacturers (and filter component vendors, etc.) end up converging on 455 kHz as the IF frequency, from the vacuum ...
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9 votes
8 answers
4k views

How can the same radio signal be received by 100s of receivers without any loss in it?

In power supply, each house connected to the grid consumes a certain amount of power which leaves less power to be consumed for the rest of the houses. Similar to that, when a radio station broadcasts ...
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0 votes
0 answers
31 views

RFM69HCW Digital IO connection setup

I'm working to setup an RFM69HCW transceiver with an ARM microcontroller. I've read over the datasheet for the RFM69HCW and I see that DIO0 is the interrupt signal, so I've broken that one out, but ...
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2 votes
0 answers
150 views

Esp32 rf design review

Preamble: this is the first time I'm working in rf circuit design, I went simple and I hope I didn't make any silly mistakes, but I still have some doubts. I am currently designing a garden programmer ...
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