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votes
1answer
58 views

Total radiation pattern in antenna arrays

let's consider a simple linear uniform spaced array: We know that, from elementary array theory, the total pattern (for instance in terms of E-field) may be evaluated, in case no phase shift is ...
4
votes
2answers
83 views

Can a phase-modulated voice radio transmission be received and heard properly by an “FM” radio?

Not necessarily an amateur radio question (but perhaps a licensed amateur should know the answer?) - I note that the specifications for marine VHF radio operating in the 156-157 mhz band call for both ...
1
vote
1answer
93 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 ...
1
vote
1answer
159 views

What may be damaged when using an internal antenna tuner on SWR above 3?

The Kenwood TS-570S comes with a warning against using the internal antenna tuner for antennas with SWR > 3, even though it may tune (e.g. at SWR 3.5 or 4). It says the transceiver or antenna may ...
2
votes
2answers
146 views

How much of the 136 - 174 mhz spectrum is actually in use?

I know that 144-148 and 156-157 mhz ranges are in use, and various fire/ems/police, but outside of that, I see a lot of earth-to-space, weather stuff and space research allotments (talking about ...
1
vote
3answers
122 views

Why do PSK modes have “bandwidth”?

My understanding of a naive PSK scheme is that you have some frequency(s), f(n), at baseband, and you modulate information by shifting the phase (what "point in time") the signal is at. Isn'...
2
votes
2answers
238 views

How does end loops on a long wire antenna affect antenna length

I've put up a "random" length long wire antenna for HF in my yard at about 124ish feet about 15' off the ground. I got this length from an online resource. Here's my questions: How does the ...
1
vote
1answer
58 views

Baofeng's won't talk to each other - but other radios receive the signal

I'm very new to this radio stuff and I've come across a problem. I have two BF-888S', along with two other radios. (Binatone Terrain 750) All of which are on the same frequency and have the same ...
2
votes
2answers
72 views

Destructive interference between two close antennas

let's consider this two planar biconical dipoles of total length and width each one 10mm, at a distance D = 25.6mm. They are excited with the discrete ports in the picture, which corresponds in this ...
1
vote
1answer
65 views

Repeater build problems

I'm trying to build a UHF repeater using two Motorola radios. I have a cable connecting the two radios that was built for doing such a project. The radios have been programmed for the appropriate ...
1
vote
1answer
74 views

How can I know (check or detect or analyze) which modulation using of my remote control switch?

Please forgive me, my native language is not English. I'm new to radio, but I have several years of programming experience. I have a raspberry pi 4 model B (...
3
votes
2answers
98 views

How do you calculate the number of turns for a common mode choke?

I want to build a common mode choke for my end-fed wire antenna, using turns of coax through an FT140 or FT240 ferrite. I can find various finished products for sale, but I want to make my own. I ...
0
votes
2answers
102 views

Identifying type of RFI by waterfall

I'm trying to identify the type of RFI I'm seeing on the waterfall in the picture below. It occurs mainly at night, every night, starting at about 6:30 p.m. and ending in the morning, and I have yet ...
-1
votes
1answer
63 views

Using inverted Yagi antennas to gather and cohere RF from the sky

Imagine a group of eight or more vertical masts. On each mast is a Yagi antenna pointed upward toward the sky. The elements are inverted with the idea being that the incoherent RF coming down is given ...
0
votes
1answer
68 views

NOAA weather broadcasts

I am getting no NOAA weather broadcasts, after loading all NOAA weather channels into memory or entering the frequencies manually on a new Baofeng UV-5R?? Why? Do I need to do something else?
2
votes
1answer
63 views

Transmit filter for Amplitude-shift keying

I want to transmit an ASK signal with GNU Radio and HackRF, the parameters are: Frequency: 27.12 MHz (ISM) Sample rate: 2MSPS Symbol rate: 2000 bps Samples per symbol: 1000 The flowgraph currently ...
3
votes
2answers
255 views

Receiving the ISS SSTV: dipole antenna configuration and orientation

In short I am trying to receive SSTV Images from the ISS (145.8Mhz) and I all have is a simple "bunny ears" dipole antenna. In what configuration (straight, vee shaped, upside down vee, ...) ...
3
votes
3answers
100 views

Does Kirchhoff's current law (KCL) apply to antennas?

I think I'm having a hard time understanding HF antennas because they go against everything I've been taught about analyzing circuits. If we look at a dipole antenna, there is the highest current in ...
1
vote
1answer
87 views

UV9RTP Slow transmit to receive

When I transmit the there is a delay in the receiving. When I let off of the mic it still transmits for a few milli-seconds. The transfer to receive is not instantaneous. Which setting controls this ? ...
3
votes
0answers
148 views

WWV interference all over the band!

I have a mid-era Hammarlund HQ-129-x. It sounds great if I don't count the motorboating. But the problem is in the middle bands. I got the radio way out of alignment, and managed (I think) to get ...
2
votes
0answers
41 views

Printed Dipole Transmission Line Equivalent Model

let's consider a printed dipole on a substrate with a GND plane: I've seen many times an equivalent model which uses transmission lines like this (reference): This model is useful to understand the ...
2
votes
1answer
55 views

Phase shifts in antenna arrays

Let's consider a simple antenna array. For instance, this three-elements equispaced dipole array: Each dipole is connected to a signal voltage source. It's well known that it's possible to choose the ...
3
votes
1answer
53 views

What is the difference between an RF amplifier's DC or quiescent operating point and the RF operating point?

I chose the resistor values in the following schematic to set the DC bias point of VCE=6V and IC=5mA because the transistor data sheet gave the S-parameters at 162MHz for these values. I learned how ...
2
votes
1answer
69 views

On the Kenwood TM-D710, what is the “D” on the B band?

I can explain almost every part of the Kenwood TM-D710(G) display except the letter "D" that appears on the second line of the B band next to the power level. I've poured over the manual and ...
1
vote
0answers
150 views

GNU Radio FM Receiver does not work on Ubuntu 20.04 nor on Windows 10

GNU Radio v3.8 with Qt-GUI on Ubuntu 20.04 Before starting on something new I always test my setup with this GNURadio hello world flow graph which I know for sure, that it used to work. The other day, ...
4
votes
2answers
63 views

What are the steps to become an amateur operator in Canada?

A little background. My uncle devoted part of his late life to ham radio, he had his callsign and would go install/fix radio systems all the time,travel across the country and would teach newcomers ...
1
vote
1answer
68 views

Cobra hand held 50wxst aftermarket antenna

I’d like to add an aftermarket antenna to my cobra HH50wxst to boost my range. My only concern is if I got a longer antenna, could it possibly throw off the SWR and damage the radio? I am totally new ...
-2
votes
2answers
85 views

Is it possible to generate RF with a speaker? [closed]

With my headphones put on I thought what if is possible to generate some induction to my brain with the headphones speakers? some RF right into my mind.
4
votes
2answers
286 views

What is antenna reactance?

I have a V5000 antenna and I’m tuning it but can’t get the Reactance (X) on my MFJ 259B down. Resistance is at 50 ohms, SWR reading 1.2 to 1.3 (I don’t give that much credence) but the Reactance (X) ...
1
vote
2answers
168 views

Loop Antenna Construction

I have a loop antenna. When I connect the probe from my oscilloscope, does the probe also act as an antenna? If so, how should I fix that? I read about feeding technique, but I still do not ...
1
vote
2answers
261 views

Signal in the center frequency of my SDR spectrum always

I'm pretty new to SDR, but I understand a little bit about RF. On all 3 of my SDR device (two RTL one HackRF) The center frequency is always full of interference from something unknown.....it doesn't ...
1
vote
1answer
50 views

Is a Foundation or Intermediate license from the UK recognised in the US?

I know that a Full license is recognised in the US, but is the same true for a Foundation or Intermediate license? On the surface they look equivalent to the US Technician and General licenses, so are ...
4
votes
3answers
339 views

SDR: How are I and Q determined from the incoming signal in quadrature sampling on the receiver side?

I'm new to digital radios and signal processing, so I apologize if this question is trivial but I haven't been able to find an answer here or by googling. Also, some terminology might be off, please ...
3
votes
1answer
41 views

Fourier transform of air breakdown impulse waveform

i am a beginner on signal processing. I learned from some papers, site online, including this forum that lightning discharge or any electrical arc emits wideband radio frequency. because the odd ...
3
votes
1answer
125 views

Open source RS41 decoder

I would like to decode the signal from a RS41 radiosonde (from a weather balloon), which are suggested open-source software to do that? I tried RS but after compiling the code and executing ...
1
vote
1answer
80 views

Need way to indicate when rotary inductor reached its limit switches on a remote homebrew motorized hf tuner

I have a homebrew motorized hf tuner which is controlled by coupling dc from the shack through two BiasTs - one topside, the other in the shack. As I reverse polarity to adjust tuner, will two LEDs, ...
3
votes
1answer
31 views

Can I send to a D-Star reflector other than the one a repeater is linked to?

I want to send some test data via a reflector, to be picked up by my OpenSpot hotspot linked to that data reflector. My local repeater is pretty much always linked to another reflector. There's not ...
2
votes
3answers
115 views

Receiving multiple signal

Maybe this is a really silly question even from me, a completely amateur... But I like to know about how's the antenna output when its receive multiple signal Is it possible different signals on ...
1
vote
0answers
32 views

Sending custom EWS over DAB+ with a HackRF One

Disclaimer: I'm aware of legal issues regarding EWS! Rest assured that there is no need for concern as this is a small-scale, proof of concept done in a controlled enviroment! Greetings! I'm trying to ...
3
votes
1answer
92 views

Kenwood TS 520 S Meter accidentally run without an antenna connected

I powered up my Kenwood TS 520 without connecting the antenna and after 1 hour realized it was not connected, after connecting the antenna I noticed the S-meter was not giving me a reading and I have ...
3
votes
2answers
188 views

SSB Transceiver Architecture - USB with Crystal Filter

I'm planning to build a 20m SSB transceiver and I want to get the overall architecture straight in my head first. Here's what I'm thinking so far, a single conversion superhet design with a 9MHz IF ...
4
votes
4answers
117 views

Understanding how quadrature heterodyning captures information from negative frequencies

The way I understand how SDR works, there is a receiver input, generally connected to an antenna pulling in signals from the ether. That input is connected to two mixers (linear multipliers), being ...
1
vote
0answers
54 views

Is it possible to setup a private network with DNS lookup using app_rpt?

I am going through a bit of a headache trying to find this information. I have a lot of people interested in a private simplex node/repeater network using Asterisk/app_rpt, the same software ...
4
votes
2answers
242 views

Is the 1.5kW power limit per antenna? What about antenna arrays?

My son KJ7NLL just got his general, and while we don't (yet?) have plans to transmit at 1.5kW, he asks if the 1.5kW limit is per-antenna? If it is per-antenna, and you use an antenna array of 8 ...
2
votes
1answer
65 views

Signal frequency domain

Hello I am a beginner on radio and also In speaking english. I hope you will understand what I say. Let's say I have an impulse generator and the air gap breakdown. I am already able to see the ...
1
vote
1answer
119 views

Can ham radio interfere with LTE wireless internet signal?

I know that there is another thread that asks a similar question however the questioner there had DSL internet, so I think my question is sufficiently different to warrant a new thread. (Can my ...
0
votes
1answer
56 views

why does time of day affect propagation when talking to the other side of the earth?

i have been told time of day matters for hf propagation. for example, 80m works best at night. but if i qso with someone on the other side of the world, it's daytime. do they just need more power? can ...
1
vote
0answers
26 views

HobbyPCB IQ32 SDR Data modes cable?

has anyone DIY datamodes cable for HobbyPCB IQ32 SDR ? Im thinking of using SPKR/MIC/PTT port and expose it either towards external USB soundcard (or USB soundcard stick), or directly to laptop USB. ...
4
votes
3answers
227 views

Electromagnetic signal from spark gap

I am a power electrical engineer college student, and I have a project to make an antenna for magnetic direction finding. My main topic is to detect lightning strikes, but its to hard due to ...
0
votes
0answers
35 views

Ofdm carrier allocator block in gnu radio

I have some very basic question of the ofdm carrier allocation in gnu radio that am not understanding.please help me to understand. I want to pass a LTE based ofdm modulated signal simply like the ...

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