All Questions

Filter by
Sorted by
Tagged with
0
votes
0answers
10 views

To obtain operating privileges after the 2 year grace

I have been under medically supervised treatment for the past few years. I have been on heavy meds. I presently am showing signs of improvement from cognitive issues which were troubling me. I ...
2
votes
0answers
20 views

What is the delay through a 1:4 Guanella balun?

I need to estimate the signal delay through the 1:4 Guanella balun shown here: Is the delay simply the delay through the winding on CORE1 or CORE2? For example, assume each winding comprises 0.1-m ...
2
votes
3answers
120 views

Why do watches with GPS receivers have an “airplane mode”?

I noticed that watches with GPS signal receivers made by Seiko and Citizen have an airplane mode. If it's a GPS receiver, it shouldn't cause interference, right?
1
vote
1answer
23 views

Can I use a directional coupler to block reflected AC current from a mismatched antenna?

Is there any kind of directional coupler device such as you find in a SWR meter that only allows traveling AC waves of one direction to pass which i could use to block the reflected wave from my badly ...
0
votes
1answer
15 views

Can received and transmitted signals on the same antenna combine to produce standing waves?

Standing waves are seen on a transmission line when for example there is a change in impedance and a transmitted wave is reflected back from one end and then the incident wave and reflected wave ...
-1
votes
1answer
43 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?

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 ...
1
vote
3answers
40 views

Is it true that standing waves on a transmission line don't cause failure of transmitting devices?

Actual standing waves have nothing to do with causing the output device in a transmitter to fail, in fact it's the reverse or reflected current which helped to create the standing waves which is ...
11
votes
1answer
2k views

Why do amateur radio operators call an RF choke a balun?

When using a balanced antenna such as a half wave dipole, with an unbalanced feed line such as coax, an RF choke can be used to block RF current emitted by the transmitter from splitting up at the ...
0
votes
0answers
24 views

Repeater identification ending (CW)

I am just starting to learn CW, and for practice I have been recording and transcribing repeater identifications that I hear. This is what I heard today: DE W9KIC/R BBG What is the meaning of "BBG"?
1
vote
0answers
29 views

What is this military radio?

Please help me identify this piece of equipment. It looks military spec, but don't know anything about it. I want to look up some history about what it was used for. Here are some photos.
0
votes
1answer
31 views

40 meter band Dipole antenna designed is not receiving any signal at 2 km distance

I am using a Pixie transceiver, giving 1 W power and 7 MHz frequency. A 40-meter band dipole antenna, providing 5 dBi gain at high angles, has been designed and connected at the output of the circuit ...
1
vote
1answer
54 views

Does an antenna work the same for pure sine waves as compared to other waveforms?

Antenna theory it seems is always described assuming that the transmitted or received signal being talked about is a pure sine wave usually at the resonant frequency. Standing waves for example are ...
1
vote
2answers
63 views

GMRS not transmitting within a half mile

I recently got my GMRS license from the FCC, and I wanted to try out a couple radios for hiking and emergency communication. I have two tenway UV-5R pro radios (these do have an FCC ID) that are set ...
1
vote
1answer
61 views

Can any one explain E,H plane definitions?

I read in some text books that E-plane is formed by taking constant azimuth angle and scanning elevation angle from -90:90. H-plane is formed by taking a plane perpendicular to E-plane. What is ...
0
votes
1answer
39 views

Frequency modulation with gnuradio

I'm trying to understand way which Frequency Mod block works in gnuradio. According to my intuition there should be at least two inputs: signal to encode base frequency / carrier signal Instead ...
0
votes
2answers
30 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 ...
0
votes
0answers
45 views

How to generate PACKET9600 and PACKET1200 streams using gnuradio [closed]

I'm trying to hide some message in the video file (for the purpose of puzzle game). I was going through https://wikipedia.org and https://sigidwiki.com I found couple of interesting protocols (FLEX ...
5
votes
1answer
54 views

DIY SA612 + RTL-SDR HF receiver: good on laptop, but huge wideband noise on Raspberry Pi

I recently built a SA612 mixer for HF reception. I used an USB-frequency oscilator to shift the incoming frequency up by 28.8 MHz. I used a random wire antenna outside my balcony and connected it to ...
0
votes
0answers
41 views

How to prepare for Antenna PhD Position Interview

I am currently a master student doing TPU-based BLE stretchable antenna, and I have an interview for an "Extremely Large Antenna Arrays (ELAAs)" PhD position. can anyone give some tips/advice on how ...
0
votes
1answer
39 views

Shifting frequency outside of the band

In theory when i need to shift some frequency i just multiply that signal by some sin or cos wave with the right frequency and than apply LPF or HPF. But when there is a wideband complex signal with ...
1
vote
3answers
60 views

Can I build a guanella balun using single strand wire instead of coax?

I am trying to homebrew a cobweb antenna and need some help understanding the guanella balun used as described here: http://www.karinya.net/g3txq/cobweb/ This author used RG316 coax around the ...
2
votes
1answer
71 views

Is the voltage at the centre of a dipole zero only at it's resonant frequency?

For transmit, the voltage at the center of a dipole not cut in the center and fed with coax and a gamma match is zero in the center at the resonant frequency. This is why apparently a 'plumbers ...
0
votes
1answer
32 views

What is the effect of coil Q on a shortened dipole?

I made a small yagi, with the driven element being a coil loaded dipole. What is the effect of coil Q in this situation? The coils I built are 18 turns of 1.2mm enameled wire wound tightly with a ...
0
votes
0answers
37 views

Is there any 2.4 GHz tuner ICs for SDR receivers?

I have a hackrf one sdr, which i use to transmit test signals. I am using ISM bands, so I can omit transmitting my callsign, checking correct sub band (FM, digital) etc. And one of most interesting ...
0
votes
1answer
19 views

Find blocks function on Gnuradio does not work

I am trying to use Gnuradio to build QPSK transmission with satellites simulation for educational purposes. Unfortunately, I am unable to add new blocks after "find blocks" (blue magnifier icon) ...
4
votes
2answers
71 views

What causes the light and dark bands (of background noise) in an HF waterfall display?

While monitoring the 40-meter band (among others) throughout a typical day/night as propagation changes I have noticed there are often bands of very low noise (black area) and others with much higher ...
0
votes
0answers
20 views

How are Amateur Radio Callsigns created? [duplicate]

When I took the Amateur Radio Technician Exam, I was given a callsign upon passing the test. How does the FCC create that callsign? Is it completely random or do the letters and numbers have meaning?
-3
votes
1answer
131 views

Carrier telephone system adaptation

In amature radio, users can use what is called a phone patch to enable them to use a phone to establish connection to another party or user. Phones are usually two wire and dont lend themselves to ...
5
votes
1answer
126 views

Does the FCC care about electrical arcs?

There are a lot of videos on YouTube from people who have built high voltage sources and are sending electric arcs from one place to another. Although they have no intention to emit radio waves, they ...
2
votes
3answers
52 views

Ideal Doublet Size 160-10 Meters

Is there considered an ideal / optimum length for a doublet for use on 160-10 meters when fed with open-wire feedline and a balanced tuner in the shack?
0
votes
1answer
44 views

What is the most common CW audio filter center frequency?

For older receivers with a fixed (crystal?) audio filter for CW, what is the usual center frequency of the audio bandpass of the filter? Or cut-off frequency for low-pass CW filters? For newer ...
0
votes
1answer
55 views

what is the center frequency

in GRC for this source block ?
2
votes
2answers
107 views

Full Duplex Radio Communication On a Single Frequency

I am an ELECTRONICS final year student and I am working on a project, "Full Duplex Radio On a Single Frequency". So is it possible to design such a project. If so then give me the idea about it, how ...
0
votes
0answers
56 views

50 Ohm Active Termination

I'm looking for a circuit topology that has unity gain, a 50 Ohm resistive input impedance, a 50 Ohm resistive output impedance, and here is the kicker, at least 60 dBm OIP3 over a 2 - 30 MHz HF ...
0
votes
0answers
25 views

Center-loaded vertical, high SWR at lower frequencies

I built a center-ish loaded coil-shortened vertical. The lower radiator is 3 meters, then the coil, then 5M more radiator, like this (Early prototype with shorter radiators and no covers for the coil ...
3
votes
1answer
40 views

What are the columns URCALL, RPT1CALL, and RPT2CALL in CHIRP?

I'm populating a CSV file to import into CHIRP. In the documentation, there's a list of CSV columns. However, that list doesn't cover URCALL, RPT1CALL, and RPT2CALL. Can anyone tell me what those ...
2
votes
2answers
119 views

Is an antenna resonant at the frequency of lowest impedance?

I understand that an antenna is resonant at the frequency where the capacitive and inductive reactance cancel out to 0. Only the resistive impedance remains at resonance. Does this mean that the ...
0
votes
1answer
79 views

Is a lightning arrestor required with a ground rod?

I am building an out building ham shack. I am planning to install an 8 foot ground rod for the antenna. Does the radio require an additional ground to the rod as well or do I need to install a ...
2
votes
0answers
49 views

Ferrite Rod Antenna Array?

The ferrite Rod is a reasonably effective Receiving Antenna for LW MW and Lower HF spectrum .It is well known that a ferrite rod is much more effective than an air cored coil of the same dimensions ....
3
votes
2answers
76 views

How do blind hams operate?

In an earlier question, there seemed to be some surprise when I (indirectly) asked about radio modes accessible to a blind operator. First question: So how do blind hams operate? If I were to be ...
2
votes
2answers
75 views

What contemporary digital modes do not require a GUI? [closed]

Assume a computer (Raspberry Pi, Mac, etc.) is used to connect to a radio (HF transceiver, etc.) via audio cable(s), USB port, or GPIO, etc. What contemporary computer DSP/digital modes, of those ...
0
votes
1answer
29 views

Limit of transmission in GSM 1800 band

What is the limit of a transmitter in the GSM1800 band (~1830 MHz)? The ETSI GSM specification states a limit of -47dBm between 1GHz and 12.75GHz (https://www.etsi.org/deliver/etsi_gts/05/0505/05.00....
0
votes
1answer
36 views

How can I design a microstrip patch rectenna that can power up 1W of payload?

I know the major components of rectenna should be Receiving antenna - Patch Antenna Matching circuit Low pass filter Rectifier - Schottky diode but I could not visualize how can we put all ...
3
votes
1answer
72 views

Turning raw APT data into an image

I apologize if this question is a little out of scope for the amateur radio stack exchange but I feel like it fit better here than over in any other forum. I have successfully parsed raw PCM data out ...
3
votes
2answers
112 views

What kind of loop antenna is this, and what is the relationship between its diameter and wavelength?

At the bottom of webpages in the advertisement swamps I keep seeing this image of an antenna, accompanied by an offer that I won't be clicking on. But the antenna itself looks quite intriguing. It's ...
-1
votes
0answers
59 views

AM transmitter and reciver [closed]

How can I make circutes which can send and recive AM wave ? I want to send my Voice but i don't the circute which can transmitter and recive
4
votes
2answers
127 views

Actual Impedance of a folded dipole at resonance

I am using a Folded Dipole which I bought when I first got my General License. It was advertised as an all band antenna. My results with it were less than the claims made by the makers to say the ...
3
votes
1answer
93 views

RF Bridge Problem - K6BEZ Antenna Analyzer

(New, simplified edit of the original question) This question regards erroneous SWR measurements of K6BEZ antenna analyzer design from 2013 using Arduino and AD9850 DDS modules. There have been many ...
5
votes
1answer
284 views

How does a Viper Antenna work?

Are any of you guys familiar with a "Viper" antenna? It came up in a recent discussion with club members for higher frequency bands (6m, 4m, 2m). I hadn't heard of it before and internet searches ...
3
votes
1answer
97 views

Do Far-Field Radiation Patterns/Gains of NEC Software Accurately and Always Show the E-M Fields “Launched” by Vertical Monopoles?

Judging from posts on the Internet, this belief commonly is considered to be valid. But what is the correct answer?

15 30 50 per page