Questions tagged [transmitter]

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18 views

Setting the maximum Tx Power value for the USRP transmitter

In order to simulate the measurements on the computer (in the WinProp environment) I have to set the maximum Tx power: To find out what the transmitter signal power is, I checked it on the spectrum ...
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2answers
121 views

How many cars/devices can connect to a transmission from a 7 Watt FM transmitter

I currently own a 7 Watt Frequency Modulation (FM) transmitter that I purchased from eBay some years ago. We are planning a drive-in cinema setup where the transmitter will be placed 5 meters above ...
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1answer
85 views

Help getting use out of an old RC radio transmitter

I have an old "Walkera-RC 2.4ghz Radio Transmitter WK-2401" radio transmitter from an RC Helicopter. I want to use this transmitter with a receiver in order to transmit some sort of data ...
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2answers
51 views

Repeater design using round robin transmitters to increase duty cycle?

I would like to build an FM repeater using a short stack of Kenwood TK-890H rigs adjusted to 70cm USA amateur band, but the model has a 100W rating with a duty cycle of only 20%. 20% isn't nearly ...
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1answer
153 views

Simple AM Radio Troubleshooting

I just got all the parts to make a simple AM transmitter from Scitoys. I followed the instructions from different websites and they still don't work. I don't know why it's not working. On my ...
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2answers
117 views

How should I go about finding the transmitter or antenna of a radio signal?

This site gets many questions about people trying to track down RFI, or interesting signals picked up on radios. Often the exact location of the transmitter or the antenna would be a valuable clue to ...
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2answers
62 views

Why do repeater duplexers have notch cavities between transmitter and antenna?

Why are notch filters used on the transmit side of a repeater duplexer? The primary purpose of a duplexer is to keep the transmitter output out of the receiver input, since they both operate at the ...
3
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1answer
78 views

Is this “floating” output single-ended or differential and against GND or VCC?

I'm looking at a simple FM transmitter output (see picture). It is from the collector of a transistor and it goes through a DC blocking capacitor before the antenna would be connected. The entire ...
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2answers
80 views

FT-450D not transmitting with microphone

I've been using FT8 on my Yaesu FT-450D for quite some time. I decided to try to talk on phone frequencies and discovered neither one of my mics will transmit. My mics are the original hand mic and a ...
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3answers
190 views

What replaces the T/R switch in modern transceiver

I have been watching and reading about the time when receiver/transmitter were separated and T/R switches were used. Current transceivers are still sharing a single antenna to transmit and receive. ...
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1answer
95 views

Reduction in transceiver power output into high SWR

How much do transceivers drop their output power, when the SWR is high? Most amateur solid state amplifiers or transceivers are (fully?) protected against high SWR, by a circuit which reduces the ...
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2answers
670 views

How to calculate power transmitted by monopoles?

I only studied monopole in sending mode or receiving mode alone but never in both modes together, I have this question which says: Two vertical λ/4 monopoles are parallel to each other with 20 ...
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1answer
101 views

Can these in-band spurs from rpitx be eliminated somehow?

I'm putting together a 2m NBFM transmitter/receiver combo using rpitx and rtl-sdr. During testing my low-pass filter I discovered that rpitx is generating spurious signals within and around the band (...
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1answer
72 views

FT450D no cw tx unless ppt is held

FT450D in cw mode does not transmit unless PTT is actuated. "BK-IN" not in display despite pressing function followed by vox/store button.
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2answers
133 views

sdr as watts and amps [closed]

Thanks to rclocher3 for helping edit more to English why closed so my struggle to get thought to English thank rclocher3 I round back too best I put in avuenue what I was asking why closed i tryed ...
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0answers
33 views

power limit on wireless FM microphone transmitters [duplicate]

I am building a "toy" radio station as a teaching tool for high school students to work with. I intend to use a small (short-range) wireless FM microphone module as the transmitter. What is the legal ...
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1answer
94 views

If i transmit on the same frequency using two separate transmitters joined together will they both add up in a reciever to produce a stronger signal? [duplicate]

If i were to use a passive transmit coupler to connect two transmitters of equal power output to the same antenna, and connect one microphone to both transmitters, and then transmit on both at the ...
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2answers
67 views

Required receiver for HX-1 (144.390 MHz) & NEO-6M GPS Module?

Context I'm launching a series of weather balloons as a capstone graduation project. Right now I am in the process of building the payload. I have been going over the different components of the ...
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4answers
111 views

Can I make signal transmitter without decoder?

I'm sorry if my title seems weird but I just started to learn about signal transmitting and I don't know where to start I'm searching about simple ways to make diy radio but I can't really ...
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3answers
258 views

Is there a way to split a frequency into channels?

Is there a way where I can take a single frequency and subdivide it into channels so theoretically I can transmit multiple voice channels on the other?
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0answers
75 views

Can I make a simple Tx/Rx antenna (Radio System) which will receive signal from BTS and broadcast/transmit it, and vice versa? [duplicate]

Consider a situation as below. I am stay in a farm field, which my house is 9.4km distance from the nearest and the only one BTS (Base Transceiver System), a cellular antenna for transmit and receive ...
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1answer
120 views

What happens when you directly couple the transmitter antenna to the receiver antenna?

I was wondering what happens when you directly electrically couple the transmitter antenna to the receiver antenna? Particularly I’d like to know what happens for FM radio broadcast. Since I don’t ...
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1answer
63 views

Unusual modulation

I've been writing a SciFi story, and it calls for something very unusual to happen. I'd like to check this idea for plausibility, but as I'm not a radio ham myself, I don't know if this already exists ...
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4answers
173 views

How is working on DC high voltages as in a tube radio different from 120VAC?

Suppose that I am familiar with the safety procedures for working on 20 A 120 VAC 60 Hz household lines. What should I be prepared for before working on high voltage DC circuits (say, 800 volts) as ...
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1answer
160 views

How does one know how a signal has been modulated

I am trying to intercept signals from a drone remote controller and decode them. Before I can do this I need to demodulate the signals. All I have is radio data from the transmitter's operating ...
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1answer
120 views

How hard to send files [duplicate]

How hard and expensive would it be to send a file from my house in London to a coastal area in Spain? It would most likely be software I want, so it must transfer perfectly, however if it is feasible ...
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2answers
171 views

Pi Matching circut for tube PA - what values?

I am working on my 80m and 40m CW transmitter and ran into a problem: I need to match the high impedance of PL504 to 50ohm coax, a Pi match seems to be the best, but I don't know how to calculate ...
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0answers
70 views

Parasitic inductance of relay contacts

I need to switch a bank of filters operating on bands from about 2MHz to 30MHz. The parasitic series inductance of the relay contact system will have an effect on the performance of my system. ...
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1answer
86 views

did static fry my uv5r?

I was hit with a big arc of static from a metal door frame. I was a little over a foot away. It stung pretty good, then my coworker told me I was transmitting. My baofeng uv5r will not stop ...
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2answers
221 views

Can I have a signal generator on while it's not connected?

The unit in question is an Elecraft XG3 test signal generator. It puts out anywhere from -107 dBm to 0 dBm. Is it safe to have these signal generators on and transmitting while not connected to ...
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2answers
449 views

How does keying a CW transmitter work?

In my handbook it talks about keying the transmitter to produce the dots and dashes. Does this mean that the operator is turning the transmitter on and off, or does this mean that the key is turning ...
2
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1answer
159 views

Where does this common spurious transmission come from? Is there a quality difference?

I decided to see what my ham transmissions look like on an SDR and was kind of shocked to see how much leaks out. The waterfall display is split between two handhelds during transmit. There are a ...
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1answer
236 views

Will I get cleaner keying by keying the oscillator, or interrupting the amplifier B+?

One of my goals as a new ham is to homebrew my own transmitter (using vacuum tubes, aka valves). Initially I'll stick with CW for the transmitter, though over time I might build an AM modulator or ...
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2answers
55 views

Simplest way to transmit beep 5-10km (3-6 miles) using FM? [closed]

I would like a simple device which enables me to transmit a beep every second or so on a chosen frequency. Is anyone aware of a product that can do this? If not, can anyone tell me what you would ...
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0answers
81 views

Can anybody identify an appropriate radio for this game? [closed]

Complete radio ignoramous here. I've been playing a game called The Blackout Club, and I'd quite like to make a 3D model of a radio set for it. The game is set around 2007 and, as in the picture ...
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1answer
60 views

Can radio waves be made to travel as or along a particle beam? [closed]

Can a laser be used as an antenna? Can a beam of any type extend transmission distance of an electromagnetic field? https://medium.com/starts-with-a-bang/this-is-why-the-2018-nobel-prize-in-...
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105 views

2GFSK 9600bps Transmitter and amplifier for 433 MHz

I'm looking for a reliable, however cheap solution for ground-space communication. I need at least 50W of transmitted power with 2GFSK modulation at 70cm band (433 MHz). Transmission will be done ...
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3answers
324 views

Long range communication with just 1W of power?

Is it possible, and how can I setup communication between stations 1000km apart from each other by using just 1W of transmission power? By communication, I mean: It can be text based It can be very ...
6
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1answer
554 views

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 ...
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1answer
66 views

What circuit to use to multiply 434 MHz by two?

I wanted to make an experimental simple 1296 MHz transmitter to have fun with my sdr dongle. But after hours of googling I realised that there is no such thing as "simple 1296 MHz transmitter". Even ...
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2answers
404 views

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 ...
6
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3answers
422 views

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 ...
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1answer
2k views

How do PTT buttons work?

I'm really new to this, and I was wondering how the whole PTT system works? I have a headset with microphone, and a Baofeng UV-82 radio. I know the radio has its own PTT button, but is there any kind ...
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1answer
160 views

Is there any way in which elevation *does* affect medium frequency (AM radio) transmissions?

This is a followup to this question of mine. From reading the wiki article, I get that: Radio waves at MF wavelengths propagate via ground waves and reflection from the ionosphere ( called skywaves)...
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0answers
473 views

LimeSDR Mini + Raspberry Pi 3 B+ Transmission problem

I am new at this. I would like to transmit an audio signal cleanly using WBFM but I see two signal peaks occur around my fundamental frequency when I start transmitting. In this case I am using a ...
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1answer
108 views

Why would a nearby antenna cause intermittent transmission?

I'm having an issue with some handheld transmitters, and not sure if they're bad, or the newly-installed antenna is bad, or if this even makes sense. I've been using a handheld Icom aviation radio (...
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3answers
2k views

What does the spark-gap do in a spark-gap transmitter?

I read the Wikipedia article about spark-gap transmitters and I have to admit that I’m even more confused as to what the spark-gap actually did. The article references this simplified circuit ...
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4answers
2k views

How to tune an FM transmitter to a specific frequency?

I am planning to organise a simple fox hunt, a family event. This includes building a transmitter. I am currently considering the following schematics: https://maker.pro/education/diy-fm-transmitter ...
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1answer
125 views

Parts for a 915 MHz low power transmitter

I'm interested in doing some experimentation with custom modulation in the 915 ISM band. Off-the-shelf radio modules use specific known modulations (FSK, QAM, etc.) so those won't work for my ...
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3answers
424 views

Weird Harmonic Issue on Raspberry PI FM Transmitter

So I talked to my neighbor about my Raspberry PI, harmonics and his emergency radio. He told me to fire it up, as we saw the FCC sticker on it, meaning it is in compliance with Part 15. I started my ...