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1500 questions
19
votes
3 answers
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 antenna feed point and traveling along the antenna…
Andrew
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19
votes
6 answers
Using a Morse code key with a computer?
Are there standard ways to connect a hand key (straight or paddle) to a contemporary computing device (PC laptop with no parallel port, Mac, Android, iOS device, etc.) for developing or improving ones Morse code sending skills?
If so, can one use…
hotpaw2
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18
votes
1 answer
How does an SWR meter really work?
For ham radio operators, the SWR meter is a ubiquitous piece of equipment. There are dozens of standalone models on the market and most modern transceivers and antenna tuners have this functionality built in.
Any ham with an interest in antennas has…
Glenn W9IQ
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18
votes
2 answers
Why do repeaters use cavity filters?
Repeaters apparently often use large, expensive cavity filters to connect the receiver and transmitter to the same antenna.
Why aren't typical electrical circuits, such as inductors and capacitors used instead? Wouldn't they be cheaper and smaller?
Adam Davis
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18
votes
2 answers
Is there a disadvantage to using a cheap HT for APRS?
Looking to build a cheap (not even inexpensive, just dirt cheap) APRS beacon transmitter. Right now you can get a dual band handheld transceiver with rechargeable battery, antenna, etc for under $31 [USD], for instance. I can't find a cheaper…
Adam Davis
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18
votes
3 answers
What is a "random wire antenna"?
Some antenna tuners claim to match any “random wire” to any HF frequency. Can one really use a random wire as a practical antenna system?
From everything I have heard, the resonance of the antenna (length, material) is what defines its performance…
Ron J. KD2EQS
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18
votes
2 answers
Ham radio above 275 GHz
I see on the allocation chart all modes and frequencies are allowed above 275 gigahertz. Has anybody experimented with this? Are there interesting things you can do on these extremely high frequencies?
The bandwidth must be amazing here; maybe…
Skyler 440
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18
votes
6 answers
What's the difference between saying “CQ” or “QRZ” in a contest?
I'm listening to (or let's say I'm trying to participate in) a contest (or perhaps Field Day), using SSB.
I noticed that a station would, after completing a contact, sometimes say “CQ” and sometimes say “QRZ”. In either case, other stations then…
Kevin Reid AG6YO
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18
votes
2 answers
How do I make a RF propagation map for a repeater?
Let's say I have a repeater. Knowing all of the information about antenna height and gain in each direction, as well as power, how can I create a map similar to this map I saw of a repeater in Illinois?
Free options are always better!
Skyler 440
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18
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2 answers
What does a noise blanker really do, and what are the side effects?
Most HF rigs have a noise blanker (NB) feature. It does reduce some types of noise (car ignition noise and such). How does it really work?
I've read it has negative side-effects with strong signals, which is why it is not enabled all the time.
oh7lzb
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17
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4 answers
Where are the baluns for VHF and higher? How can one be made?
In another question, commenters recommended that I look into adding a 1:1 balun to a dual-band dipole to eliminate the feedline as a radiator. As I understand it, a 1:1 balun also functions as a choke, but is more efficient because... reasons?
When…
William
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17
votes
9 answers
Is packet radio possible on Baofeng UV-5R and similar HTs?
I am curious to know if it is possible to do packet radio on VHF/UHF using the UV-5R... I have seen some invasive hardware hacks, but without modifying the radio itself (firmware, hardware) it's my understanding that you can only toggle send/receive…
user400344
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17
votes
1 answer
How do emergency nets work?
In movies that depict amateur radio in emergencies, the hams' worldwide communication network invariably is able to pass messages between individuals. As an amateur that has been primarily interested in the technical sides of the hobby I am not at…
pyHazard
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17
votes
4 answers
Using my Baofeng UV-5R to talk to walkie talkies
I have a few walkie talkies at home and sometimes I connect my UV-5R to them to talk to them and act as another walkie talkie. At one time, I built a little simplex repeater out of it. Should I not be doing this? I don't think the other walkie…
Skyler 440
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17
votes
4 answers
What bands and modes will give me voice at 3,000 miles?
I pursued Amateur Radio primarily for local emergency communications and as part of my electronics education. My only radio right now is an inexpensive 2m/70cm HT which is good for local weather spotting and emergency operations.
I'm interested in…
Adam Davis
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