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2
votes
2answers
54 views

Will ferrite rings around a metal pole hide it in an RF sense from my vertical 10 m Yagi?

If i mount my vertical 10 m 4 element yagi directly on a metal pole so that the pole is between the elements and so messes up the radiation pattern and input impedance, if i put lots of type 43 ...
2
votes
1answer
189 views

When I am told that a dipole must have a determined length, does that include the space between both elements?

I am trying to build an antenna for receiving NOAA satellites and I need to build two 137,5MHz dipoles. When I enter the frequency and width of the wires in a calculator, I obtain that $λ/2=1.09\,\...
1
vote
1answer
70 views

What is meant by CC 7?

I am seeing a repeater on RepeaterBook 444.8375 +5 MHz CC 7 Portland, Providence Portland Medical Center Multnomah WA7HAA OPEN ON-AIR I'd like to programme ...
4
votes
2answers
71 views

Basic antenna matching theory?

I'm fairly new to antenna matching, other than having built a base loaded vertical. I'm also new to EZNEC and I tried to simulate an horizontal loop. I arbitrarily chose a 10x10M loop, so I added 4 ...
1
vote
1answer
75 views

Grounding for an upper floor shack

My shack is on the second floor, 4m from the ground. My main antenna is a base loaded vertical, using the metal roof (10x6m) as a ground plane. When I operate in 20 and 40 meters, it's pretty ...
2
votes
2answers
61 views

How to estimate a dipole feedpoint impedance?

An ideal dipole, at resonance, will have an impedance around 73 ohms. A folded dipole, around 280 ohms. How can I calculate the impedances when not at resonance? Let's assume I have a span of 15M in ...
0
votes
0answers
24 views

UHF cubical quad VNA analysis interpretation (part2)

This is the follow up to: UHF cubical quad VNA analysis interpretation This is a S21 and S31 analysis of an oversized 385 Mhz 50 Ohm to 90 Ohm balun between 100 Mhz and 600 Mhz I tested phase ...
1
vote
1answer
58 views

Are there any satellite email reflectors?

I'm just getting started using amateur satellites and would like to subscribe to an email reflector, but I can't find one. Is there anything out there?
1
vote
1answer
56 views

Rotatable Dipole & RF Choke

I have a Diamond HFV-5 (rotatable dipole) in the attic fed by ~30ft of coax. The antenna system comes with a Balun at the feedpoint. Would it be worthwhile to add an inline RF Choke (Unun) in addition ...
0
votes
2answers
56 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 ...
0
votes
1answer
56 views

Lead in wire size [closed]

I have a copper wire antenna about 100 feet long that I have relocated and now need about 75 feet of lead in wire. What type & size of wire should I use?
1
vote
1answer
60 views

What is an expected sensitivity of a crystal radio for 7 MHz band?

I'm learning to build radio receivers and transmitters. I've successfully build some oscillators, amplifiers and filters before and decided that to build a simple crystal radio would be a logical step ...
5
votes
5answers
128 views

How to match low impedance of NVIS Dipole?

I want to match a 50-ohm coax feed wire to a 40-meter NVIS half-wave dipole. NVIS antenna examples I've found are usually based on a regular dipole (72 ohms in free air). However the impedance drops ...
1
vote
1answer
106 views

Legal aspects of the HackRF one / SDR in Switzerland?

I would like to know, what I can legally do with SDR / a Hack RF One in Switzerland? What are the limitations concerning sending and receiving? Do I need any licenses for that? If so, which ones, ...
1
vote
1answer
66 views

audio problem with SDR on MacOS

I'm experimenting with SDR on MacOS High Sierra. Trying both CubeSDR and GQRX and experiencing similar issues with both. The applications seem to work, but the audio is choppy and chipmunk-like. ...
3
votes
2answers
79 views

What is really happening during RF ionospheric refraction?

We all know that the ionosphere — when charged — refracts RF energy, but why? In other words, what is actually occurring at a molecular level to cause radio waves to bend back to earth because of ...
1
vote
3answers
81 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?
0
votes
0answers
25 views

Is there and data anywhere showing if amateur radio operators are more likely to get cancer from exposure to RF?

Is there and data anywhere showing if amateur radio operators are more likely to get cancer from exposure to RF ?
0
votes
3answers
121 views

Why are no 2w FRS walkie talkies on the market?

I have read that the new laws regarding FRS radios state that you may use up to 2 watts power, yet I can't find a single 2 way radio that advertises 2 watts power; only .5 watt, or they don't state ...
2
votes
3answers
145 views

Can I build a Yagi antenna for my Baofeng UV-5R?

I would like to build a Yagi antenna for my Baofeng UV-5R, but I'm a total newbie when it comes to amateur radios. The antenna will be for UHF and shouldn't be too long (like 1.5 meters max). So my ...
1
vote
1answer
27 views

How to use HT microphone with two jacks (Kenwood connector) as a substitue for KX-3 microphone?

The original microphone for KX-3, Elecraft MH-3, is insanely expensive. What changes would be necessary to convert a cheaper speaker/microphone for a FM handheld transceiver? Is there any ready-to-buy ...
5
votes
1answer
83 views

Counterpoise wire voltages?

One practice which seems common when operating temporary or portable QRP, SOTA, etc., is to throw a counterpoise wire out on the park lawn or shrubbery, mountaintop or hillside or parking lot ground, ...
0
votes
1answer
43 views

Using Gaming Headset on FTDX3000

It seems like a gaming headset is a cheap option for my radio, considering I have a 3.5mm to XLR adapter, along with an adapter for the Yaesu mic input (from XLR). However, what I'm not sure about is ...
2
votes
1answer
50 views

Output impedance of TAPR QRPi?

I'm a newly licensed amateur and have decided to start out by trying WSPR on a Raspberry Pi equipped with TAPR's 20m QRPi. The QRPi write-ups I've read always talk about long wire antennas but I'd ...
2
votes
2answers
56 views

Grounding of a portable setup

I am occasionally using an extremely simple shortwave portable setup consisting of a battery, the transceiver, a short coax feedline and a vertical half-wavelength vertical antenna with a transforming ...
3
votes
3answers
82 views

What is the typical latency of a SDR setup running on a desktop computer?

It's well-known that the signal processing of an SDR adds a significantly amount of latency, the SDR software on the computer adds more latency due to data buffering, FFT, decoding, demolutaion, audio ...
4
votes
2answers
56 views

2 meter Mode Options

FM seems to be the most popular in the 144 to 148 MHz Amateur Band .Narrow band is used for spectrum conservation . SSB is also used but is more common on the HF bands .Would SSB provide any ...
4
votes
1answer
50 views

Voltages in a beam antenna's passive elements?

This question has good answers for the voltages reached in portions of a dipole antenna during transmit. In a beam (Yagi or Yagi-Uda) antenna, do points along passive or parasitic elements (...
1
vote
1answer
63 views

How does one identify the transmitting station at the end of an FPV video transmission?

I recently received my technician license, with the purpose of sending FPV video (on 5.8GHz) when flying model aircraft. However, I cannot figure out how to perform station identification when ...
3
votes
0answers
40 views

What dot means in JTDX FT8 received messages?

What dot near country means in JTDX? Maybe LOTW?
2
votes
1answer
63 views

What sort of antenna would use a bicone or lozenge-like arrangement of vertical wires?

In another QA here, there's a picture of an antenna I identified as a "discone": What are these antennas used for? One commenter noticed that antenna was actually a "Discone, but no disc, just the ...
2
votes
2answers
110 views

Will using a 1:1 balun at the feedpoint of a center feed dipole result in no common mode current on the outside of the coax?

Will using a 1:1 balun at the feedpoint of a center-fed dipole when using coax result in no common mode current on the outside of the coax ?
1
vote
0answers
60 views

Compare signal strength with Software Defined Radio

I want to compare field strength with an RTL-SDR dongle or HackRF One. With comparing I mean being correct relative to one another, like if I know field strength of one in mW/m^2 then I know the other....
1
vote
1answer
41 views

How to connect MX614 to an ATmega 328p and a DRA818V to make an APRS transceiver

I am in a process of making a nanosatellite on which I am considering putting an APRS digipeater. I know about micro-modem based on ATmega 328P but it is pretty power hungry. MX614 has really good ...
4
votes
2answers
96 views

Base vs center loading a vertical antenna

I currently use a homebrew 40/60/80m vertical consisting of a 5M aluminium tube with a multi tapped coil at the base. The ground plane is the metal roof at my house, and the antenna is not centered in ...
1
vote
4answers
106 views

Can a foreign student take a US license exam in the US and use that license in China?

The event I'm currently attending hosts Ham exams, and it's kind of likely that the student would pass on first attempt; would it make sense for him to take the exam? Can he just go home to China and ...
5
votes
3answers
481 views

Cheap antenna for new HF HAM

I just got a 100W HF radio and I am new at this. What is the cheapest antenna I can hook up without burning up my radio or shocking myself?
6
votes
2answers
64 views

Can an ultra-wideband system transfer data at high speed without precise clock synchronization?

Recently, ultra-wideband technology has been in the news again. From the Wikipedia article: UWB transmissions transmit information by generating radio energy at specific time intervals and ...
0
votes
1answer
90 views

Center-frequency parameter for gnuradio noise generator flowgraph

Can I add a center-frequency parameter for my noise generator flowgraph, is there a different noise source that has this parameter other than the generic noise source block?
9
votes
5answers
140 views

Practical limits to maintaining coherence in an HF channel

Lately I've been thinking about weak signal communication on HF. Very weak, like weaker than even WSPR could achieve. It would be nice if one could simply take any existing modulation and slow it ...
3
votes
0answers
34 views

What value goes in the AX.25 PID field if the Layer 3 protocol is not defined in the standard?

I am working on space-ground networking for a Cube Satellite, and one of our candidate Layer 2 protocols is AX.25. We haven't settled on a physical layer, but it's likely to be some form of quadrature-...
3
votes
3answers
126 views

Can a person in Portugal get an amateur radio license in another country?

In Portugal, to transmit, one must take the category 3 exam, then wait for 2 years to take the category 2 exam. While these 2 years go by, one cannot emit on his station. I find this rather annoying. ...
0
votes
2answers
49 views

Local Relay with static

On our local Relay there are from time to time transmissions, where only static can be heard. Most transmissions via relay can be heard clearly. What could be the cause of this?
-4
votes
1answer
85 views

Wifi inside a rocket

I want to understand, as most rocket uses LAN cable and switches to communicate between stages. Is it possible to replace with WiFi? Although it's will be complex system but one idea to make each ...
0
votes
1answer
67 views

Passive antenna system as a Wi-Fi repeater [duplicate]

I want to extend WiFi signal using a passive repeater between two isolated boxes (have to make both box wireless). Transmitter antenna from box A is placed in the gap between box A and B. In the same ...
3
votes
1answer
66 views

Help understanding transmission loss of trivial circuit

I was trying to DIY a VHF/UHF diplexer, and got some weird readings from the VNA. By debugging I reached this trivial circuit: Which has the following frequency response: I'm trying to figure out ...
1
vote
2answers
73 views

Beam antenna changed directivity

My Hy-Gain TH6DXX antenna has been up on a tower about 20 years, with excellent results. Suddenly, the gain of the antenna is off the side; in other words, when the boom is broadside to the ...
5
votes
3answers
176 views

ARRL handbook as a reference for all your radio learning needs?

Looking to take up learning understanding everything from basic electronics to how today's wideband radios work, so that I can build my own radio systems (not just ham radios), and talk radio concepts ...
1
vote
1answer
61 views

New quad-band mobile receives while transmitting?

I've got a week-old TYT TH-9800, a quad-band (10/6/2/70cm) mobile, Chinese knock-off of a Yaesu HT-8900. So far, I love it -- several times the power of my HT, and a better antenna actually outside ...
2
votes
0answers
38 views

Demodulating ISO14443 (part of NFC) using SDR?

I'm looking for info on demodulating both sides of an ISO14443 communication using a cheap SDR, preferably an RTL-SDR (R820T2+RTL2832U). The application is passively monitoring an NFC exchange for ...

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