Amateur Radio Stack Exchange
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1500 questions
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Why do biconical antennas have a wide bandwidth?

Why does a horizontal biconical antenna have a wider bandwidth than a dipole of similar length? What's the physics behind the biconical geometry having a bandwidth uncoupled from its length in wavelengths, as for a (near) resonant half-wave dipole.
hotpaw2
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Circuit to send MCW on 2m FM

I regularly practice Morse with a friend on 2m NFM by holding our tone generators, which we also use for personal practice, close to the microphone. We send text by CW, read it back, and discuss how we are doing and how can improve our "fists".…
Harry Weston
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Is there any PC remote control software for the Baofeng UV-5RE Plus?

I saw on YouTube that some software, with another brand transceiver, can command the transceiver to scan a range of frequencies and display a running waterfall display of scanned results. Can such a setup work with a Baofeng UV-5RE Plus transceiver?
EEd
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Non-inductive resistors

When we use a "non-inductive resistor" to check the output impedance of say an unun, say 50ohm 1:1, what resistor type is actually non-inductive, or does it not really matter as long as the leads are short and frequency is low? I know there's…
t252
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SDR - FM Radio station interference

I want to learn about software defined radio and how wireless transmission work in general. So I started messing around with SDRSharp and a little antenna I bought. I figured I would start looking at known frequencies like local radio stations.…
DotNetRussell
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Does amateur radio induce a health risk?

Electromagnetic Exposure wise, does Amateur radio (Particularly 1.8 to 440 megahertz) induce a health risk due to RF radiation? Other than the Maximum Permissible Exposure (MPE) limits, which will cause RF burns etc., are there any studies that…
Skyler 440
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Power rating of a selfmade air coil

A colleague was winding an air coil himself. It's a 110µH coil with 200 windings for an 80m antenna, intended to be used on a 600 W transceiver. He used a copper lacquer wire with 0.6mm diameter. After finishing the coil, he wondered whether 0.6mm…
Thomas DK3TU
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Resonant RF Transformer Substitution

I'm looking at a RF transformer filter design that appears to be using the primary-side transformer inductance as part of a second-order band-pass filter (first schematic). This isn't the only filter in the design, but I believe I have isolated it…
W5VO
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Do ethernet-over-power adapters interfere with radios?

I remember not long ago seeing a lot of chatter in the ham community about large-scale "Broadband over Powerline" (BPL) systems causing harmful interference across several bands. Does similar interference happen with SOHO "Ethernet over Power"…
KJ4JTN
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Purpose and sizing of capacitors placed across RF push-pull power amplifier transformer windings

I keep finding RF push-pull power amplifier designs specified with a small(-ish) capacitor across the primary (or secondary) windings of the coupling transformers. Here's an example: This is one example with capacitors across all windings, but I…
Buck8pe
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Transmitting Morse Code as Tone vs. Carrier

Normal CW is just carrier on/off; this means simple transmitters are possible. The BFO of the receiver is adjusted to give a tone in the speaker within the audio passband. Narrow band filtering is done and noise performance is good. I have seen some…
Autistic
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Extra class first?

I want to get my ham license. The first 2 exams are not bad but the 3rd one is really hard. I heard it's best to start with the 3rd license because one can get a good call sign. Is this true and is it worth it?
Ownt
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So how do HF nets work, anyways?

I'm familiar with VHF/UHF repeater-based nets and the general concept of how nets work (net controller that you check in with, net controller says who talks, people send it back to the controller after talking, and so on). But how do HF nets work?…
QuantumMechanic
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Suggested method for boosting 0.05 watt transmitter up to 10+ watts?

Long time ham operator here, new to this particular challenge - I have a software defined radio transceiver that I'd like to try and use to make contacts on HF, in particular 20-meters. Tuning within the 20-meter band is no problem but the…
Brad Hein
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What cause the spectrum peak of `center frequency`?

I use gnuradio and fosphor to view the spectrum from USRP B210, default gain set to 34, output looks like concave as below: Nothing changed just set gain to 35, output become flat, looks like convex: Whatever center frequency I set,0 frequency…
kittygirl
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