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1500 questions
7
votes
2 answers
Which country’s hams have the longest call signs?
Not including special event callsigns, which group (country/class/etc) of hams have and use the longest callsigns?
I know that theoretically the longest would be a (3x4) or 8 character callsign but are these in use? I’m interested in which…
RoboKaren
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7
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1 answer
Is there a legal limit to the bandwidth of a signal used in the amateur bands?
While a normal voice channel is ~10kHz-15kHz in bandwidth, some digital modes can be significantly wider.
Are there any legal restrictions on how much bandwidth I could use for amateur radio communications (e.g. video chat over ham radio)?
Stack Tracer
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7
votes
2 answers
Morse Code meta-command sequences?
When using Morse Code as an accessibility/disability communication or input method, are there any non-alphanumeric dot-dash sequences that are more common or more suitable for meta-commands, such as “speak the last string”, “send command string to…
hotpaw2
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7
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2 answers
What is the maximum number of turns in a ferrite core used as a common mode choke?
Is there a way to estimate the maximum number of turns which can be used with a ferrite core used as a common mode choke?
It is known that the impedance of such a choke is proportional to the square of the number of turns and so there is a strong…
Chris K8NVH
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6
votes
4 answers
Does oxidation of the antenna elements have any impact on the signal quality of the station?
So I'm still QRT; apart from a brown-out on the rig, the support on the inverted-vee toppled over in high winds.
Thanks to the topple-over I discovered the conductors (SWG 16 bare copper) had started to turn greenish-black; a sure sign of…
VU2NHW
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6
votes
2 answers
DIY lightning arrestor - gap size?
I have an antenna that's well above the treeline, and I've heard I can add some small amount of protection by placing two bolt heads a short distance from each other, one connected to the antenna, the other connected to the ground rod.
What distance…
Adam Davis
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6
votes
2 answers
Has anyone actually heard or used rare Morse code characters on the air?
When I got my license about 50 years ago, I believe the only punctuation marks on the test were the period, comma, question mark, and slash mark.
Once on the air, I heard and used the usual prosigns, [AR], [BT], [SK], [KN]. I also frequently heard…
Michael
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6
votes
2 answers
Small band-pass filter for HT?
I'd like to add a band-pass filter to my Baofeng UV-82 to make it comply with the spurious emissions requirements. Ideally it would be a rigid device with SMA or BNC connectors that would fit between the radio and the antenna.
I'm open to building…
mrog
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6
votes
1 answer
Why is the neper a useful unit for transmission line calculations?
SWR Measured at the Transmitter versus SWR at the Antenna says the neper is "a more convenient unit for transmission line calculations".
Why exactly? What is a neper, and what about it makes it more convenient than the more common decibel? Are there…
Phil Frost - W8II
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6
votes
3 answers
What is dB(μV/m), and what are its applications?
Many radio coverage tools yield results in dB(μV/m). For example, CRC-COVWEB or nearly any tool based on the Longly-Rice model.
The unit occurs in regulations sometimes as well. For example, maximum permissible exposure limits may be given in V/m,…
Phil Frost - W8II
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6
votes
1 answer
What makes a good emergency-capable QRP rig for travel?
It's wintertime, which drives the concept of emergency preparedness here above the 45th Parallel. Am emergency-capable QRP rig is an excellent item to stuff into one's Go Bag or vacation gear, always but especially now.
What's an essential minimum…
K7AAY
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6
votes
2 answers
Can I transmit on 2 frequencies simultaneously?
Lets say I want to call out CQ on 145.340, 145.940, and 146.140 at the same time, am I allowed to call simultaneously on all three then monitor all three for replies?
Skyler 440
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6
votes
1 answer
Sine signal distorted in GNU Radio
I am starting off with the Ettus Research lab-1 - lab-5 tutorial to learn GNU Radio. I have set up the following super simple flow graph. I am using WX GUI as it is what used in the tutorial.
This flow-graph works well for low frequencies. As…
Denis
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6
votes
3 answers
Is there a special term for amateur transceiver speakers or anything that makes them different from any other kind of speaker?
When I bought a secondhand FT-7800R at Field Day 2017, I received an MLS-100 external speaker with it. I installed it recently and having the speaker more than an inch away from the radio's mounting surface is great.
I'd like to buy more external…
William
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6
votes
1 answer
Why do some antennas list modulation type alongside power rating?
Looking at HF antennas I've noticed that occasionally I'll see power ratings similar to "200W (SSB)".
Why would the modulation matter for an antenna's power output rating, and in the absence of other information how does one properly derate such an…
Adam Davis
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