All Questions

-1
votes
0answers
22 views

signal generator using usrp [on hold]

Is it possible to generate signal using GRC and transmit it through USRP and collecting the output through CRO or spectrum analyzer or through signal hound SDR?..IF SO what are the blocks to be added
2
votes
1answer
42 views

FM Receiver on GNU Radio with RTL-SDR fails to produce any output sound

Here is how the FM Receiver I made using the GNU Radio Companion. (Basically, I was following this tutorial by VYE6Y on youtube.) FM Receiver Problem: Unfortunately for me, the GNU Radio gives no ...
0
votes
2answers
89 views

How to reduce voltage ripple of a linear power supply?

I made a simple linear power supply for my transceiver using 12V 30A transformer, four diodes RHRP3060 forming a rectifier and three 30_000 µF capacitors connected in parallel. I also used a 200 Ω 50W ...
2
votes
1answer
23 views

Where is the speaker on the Yaesu FT-857D?

I'm considering buying a Yaesu FT-857D for car mount and I'm now concerned the speaker is on the body and only the body and not on the head unit. Where's the speaker? Can a mic contain the speaker ...
9
votes
1answer
2k views

Why would you need a signal generator to receive early satellite transmissions?

I recently watched, on You Tube, a NOVA program about the British school masters and students who were the first to publish the news that the Soviets had started launching satellites from a new launch ...
-1
votes
0answers
42 views

What is the mixing frequency for the station AM1000, which uses the radio band 995-1005 kHz? [duplicate]

A superheterodyne AM receiver down converts the AM signal from its broadcast band to a fixed intermediate frequency(IF) band where amplification takes place. The IF centered at 455KHZ What is the ...
0
votes
2answers
53 views

Is the Nyquist rate independent of the power of the analog signal being digitized?

In analog-to-digital conversion, how independent is the Nyquist rate from the power of the signal?
4
votes
2answers
76 views

How can I calculate current distribution on an end-fed dipole antenna in theory?

I understand that in a half-wave center-fed antenna current distribution has a sinusoidal wave approximately, so the current in the center has max value and it has to become zero at the ends of dipole ...
0
votes
1answer
41 views

Cabling question between two devices

Here is my schema. I would like to connect a device using SMA connector with RG 174 to an attenuator of 30 dBm with SMA connector. On the other side the attenuator is connected to a SMA-UHF converter ...
0
votes
3answers
57 views

Voltage Converter for Amp

I have a chance to get a 1 kW amplifier with a 220V plug dirt cheap from a friend of mine, but I only have a 110 outlet. The 110 outlet is on its very own 20A breaker with no other outlets. Could I ...
2
votes
1answer
121 views

What did I just do to my rig? Audio went crazy and had to reboot

Video I was experimenting with different settings on my IC-7300 and trying out manually controlling the RF Gain with AGC off. Too much gain for a moment caused audio clipping followed by the audio ...
3
votes
1answer
73 views

Are there reasons why a receive-only wire antenna should not be λ/2 in length?

The answers to this question explain why it's difficult to transfer power from a transmitter to an antenna that is λ/2 in length (or a multiple for long wires, or as half a dipole's length). Are ...
-1
votes
0answers
40 views

Estimation of necessary input signal attenuation [closed]

I want to connect two devices via coaxial cable that normally use radio frequencies to communicate. The transmitting device uses a transmission power of 5 dBm to 15 dBm (i.e. 3 mW to 30 mW) to ...
0
votes
2answers
106 views

Amateur wanting to re-enter ham radio legally

I'm an Amateur Radio enthusiast from way back; mostly CB and 10 meters. I have a couple of hand-held Baofengs that I want to use for family communications and as a backup link in case of emergencies. ...
0
votes
0answers
19 views

AREDN .mesh node addresses work on first but not second router

I have a Nanostation router that is part of a mesh, and a wifi router connected to it, which I can get to http://localnode.local.mesh:8080/cgi-bin/mesh now that I ...
3
votes
2answers
81 views

Yagi vs Parabolic Dish for 2.4GHz Campus Wifi from 1,800ft away?

My apt balcony is 1,812 feet exactly from my campus's Wifi access point behind a triple pane, brick, 4th floor building window. There is a clear line of sight. I was interested in seeing if I could ...
1
vote
0answers
54 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 ...
2
votes
3answers
125 views

Why long wire antenna length shouldn't be a multiple of λ/2?

Numerous sources say that LW length shouldn't be a multiple of λ/2 for any frequency in interest. This will cause the antenna to have a high impedance at this frequency. Since the coax cable impedance ...
8
votes
1answer
462 views

Who funds amateur radio satellites?

I am currently studying for my Technician Exam and I am amazed at the sheer number of amateur radio satellites in orbit. Knowing how expensive it is to launch something into space, and assuming there ...
2
votes
2answers
100 views

How to identify a practical HF communication receiver?

I've recently purchased a Hallicrafters S-120 -- 4-tube superhet receiver from the 1960s, continuous tuning from 540 kHz to 30 MHz, bandspread control, and a regenerative IF that doubles as a BFO for ...
0
votes
1answer
97 views

Why do the metres seem to be increasing with frequency?

I went to the ARRL's band plan site at https://clatsopauxcomm.org/index.php/technical/arrl-band-plan, and the first table began with the 60-metre band, which starts at 1.8MHz and ends at 2.0MHz. ...
1
vote
3answers
86 views

Modulation basics

I have a new interest in RF modulation and read the O'Reilly book electronics cookbook. I understand that in FM you start out with a carrier wave and then it is modulated but I don't understand if ...
3
votes
1answer
66 views

Pair of Baofeng BF-888s stopped communicating after reprogramming - what to do

I got 2 Baofeng 888s off Amazon and reprogrammed them to the 16 legal channels (for unlicensed use) in Germany, up from 446.00625 MHz in 12.5 kHz steps. I used both CHIRP and a software called ZT-V68 ...
0
votes
2answers
51 views

VOX mic that emulates PTT

I have a radio that does not support VOX, but then I got the idea that there might be a VOX mic that sends the PTT when VOX is activated? Basically a mic that will "push" the button for me. Does that ...
4
votes
1answer
135 views

How to find something disrupting car key fobs across a parking lot?

Apparently there's a parking lot in which car key fobs are messing up: Key fobs that suddenly won't unlock vehicles. Cars that won't start. Alarms that go off for no reason and can't be quieted. ...
4
votes
2answers
287 views

How did the terms like QRZ, QTH, and other forms of ham shorthand evolve?

I've wondered if many of the abbreviations are empty, or if they are similar to the recursive acronym like PHP and GNU. For instance, I learned that CQ mimics the two syllables of a French word for ...
1
vote
1answer
78 views

Who has the ability to physically manipulate a repeater's controls?

I know that repeaters on VHF and UHF are primarily automatic, but there will be times when they will fail, or something is not working. The repeater may not respond to the remote control. In these ...
0
votes
1answer
56 views

Tuning a Homebrew MURS

From online directions, I made a MURS antenna. The 1:1 SWR is at 142.000 and I want to tune it for 146.500 (therebouts). I know I need to shorten this antenna. I would like to confirm that I do NOT ...
3
votes
2answers
98 views

Shortwave antenna wire — do I care about “corona discharge”?

Just researching an outdoor long run shortwave antenna. I found some cheap wire online but it said it is resistant to corona discharge: Will satisfy a wide number of applications related to medical,...
1
vote
1answer
76 views

How large and where should a perimeter ground be installed?

From a comment on How can I protect equipment against a lightning strike? Most of the damage from nearby strikes comes from strong voltage gradients over the ground or between the ground and ...
1
vote
1answer
54 views

ax.25 error shown in direwolf. Fails on channel 8, then 2, then works

Using a Raspberry Pi 3B, Signalink, HT, direwolf and ax25-tools and ax15-apps. All up to date. Clean start. Commands: ...
2
votes
1answer
63 views

What happens to the transmitted power cancelled out by a yagi antenna's reflector?

For a yagi antenna, for transmit, does the waveform traveling away from the driven element towards the reflector get cancelled out by the reflector and then simply disappear ? Or is that cancelled ...
0
votes
1answer
86 views

Antenna relay switch design

I want to build a generic multi-antenna switch using relays. Many projects on the web have done this but the relays have silver contacts. This would be fine if I were to transmit to all antennas so ...
0
votes
1answer
45 views

Bluetooth icon on Yaesu FT-1D display: Is there Bluetooth integrated?

I've recently come into possession of a Yaesu FT-1DR, and one of the first things I noticed is that it has a bluetooth icon on the screen! Turn up the contrast and look carefully at the line of icons.....
4
votes
2answers
73 views

What additional information do I get from an RF ammeter, as compared to a regular SWR/wattmeter?

I've grown up using SWR/power meters. They're "simple" devices: They show forward and reverse power, and show the standing wave ratio. They, however, do not show antenna efficiency. New hams are ...
4
votes
3answers
412 views

How far do radio waves travel?

I have read that radio waves just keep travel but the signal gets weaker because of how the wave spreads. Ok i get this but what confuses me is that satellites emit signals from space that our phones ...
1
vote
2answers
68 views

Why some hams test their baluns with an SWR meter?

There are videos on YouTube that show how to make a 1:1 current balun. When the balun is done some people connect a 100W 50 Ohms resistor to the balun and measure SWR say in 7.000-7.200 MHz range. If ...
0
votes
1answer
38 views

Will the quantization noise be increased if the step level is increased?

Will the quantization noise be increased if the step level is increased? I was wondering about the relationship between the step size of the quantizer and quantization noise,
3
votes
2answers
86 views

Do MRI machines use the ISM band, and do they generate audible CW signals?

I've recently had an MRI, and after studying chapter two and three of the ARRL manual, I've got a better understanding of how my MRI machine might have worked. Now, I am curious to know what would ...
2
votes
1answer
53 views

Can an indoor antenna damage unshielded electronics?

I have a 25w radio running through a ~4.5db gain antenna. If I use a 4W HT indoors, I can hear a loud buzzing noise emmanating from my computer speakers. If I used the 25w mobile with the 4.5db gain ...
5
votes
4answers
155 views

Why are there differences in antennas that depend on electrical component and magnetic component of a radio wave?

I understand the idea that when we are targeting the electrical component of the radio waves we need to have some form of a linear conductor that receives the electrical component, this creates a ...
6
votes
2answers
82 views

Why can I receive a vertically polarized signal on a horizontally polarized antenna on HF and vice versa?

One explanation I found is that a signal reflected from ionosphere is always circularly polarized. Thus it can be received by both vertically and horizontally polarized antennas (naturally, with 3 dB ...
1
vote
1answer
56 views

is KPA100 a good amplifier for Yaesu Vx-8Dr

I am interested to explore what a Yaesu VX-8DR radio can do and would like to add an amplifier to it. One of the AMPs that seems to work with a 5W input is KPA100, I am still doubtful how the Yaesu ...
1
vote
0answers
28 views

Any reception reports from ExseedSAT1 yet?

My answer to the question Where can I find the TLE of ExseedSat 1, India's first ever private LEO satellite? is currently that while 60+ objects are being tracked from this mutli-payload launch, ...
1
vote
1answer
46 views

ICOM IC-910h How much bandwidth does it listen when receiving USB and FM?

CD-audio has a bandwidth of 22kHz. CW usually has a bandwidth between 3 to 5 kHz. But I am wondering what is the bandwidth my Icom IC-910H can listen to in both, the SSB and the FM mode? Also, what ...
5
votes
3answers
153 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 ...
9
votes
2answers
73 views

Local phonetic alphabets

In Russia hams use two phonetic alphabets - the regular one (Alpha, Beta, Charlie, ...) and a localized one (Анна, Борис, Цапля, ...). When a ham calls CQ in Russian (which by the way is pronounced ...
0
votes
1answer
65 views

mixing frequency of intermediate frequency (IF) and radio frequency (RF)

AM broadcast signal covering 995-1005 kHz radio frequency (RF) range is to be down-converted to an intermediate frequency (IF) range of 395-405 kHz where main amplification takes place in AM receivers....
1
vote
1answer
35 views

Measuring S21 against TX-RX distance (a.k.a path loss modelling) with a network analyzer didn't give expected results

Task: Path loss modelling Target frequency: 433 MHz; Laboratory environment: in a basement where there were other equipment and metal shelves. A few acoustic absorbers were placed around the setup. ...
-1
votes
1answer
40 views

Skin effect for a modified antenna with a high frequency pulsed DC

A direct current will be interrupted by a high frequency switch. It seems , that in a wire, connected to the source (the antenna rod), instead of pushed back- and forwards electrons, the electrons get ...

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