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2
votes
3answers
2k views

Choke at antenna and feedpoint?

I'm planning on putting up a G5RV. From the ladder line I connect 5m coax to the shack; would it be worth doing a common mode current choke at both the antenna feedpoint and the coax feedpoint? (I ...
21
votes
2answers
3k views

If I hear a distress call, what is the correct procedure for helping the person?

If during normal operation, I receive a mayday or pan-pan call, how should I handle this? Am I required to provide help in this situation, and what can I do to make sure I give all the assistance ...
6
votes
2answers
4k views

Does a person still need a ham radio license?

Way back when, if my recollection is correct, the requirement for using ham radio was to have a license and the required skill was some level of Morse code proficiency. I have heard that Morse code ...
7
votes
2answers
179 views

Moving from Australia to the US, Amateur radio license transfer?

Moving from Australia to the US, is there a way to transfer my license in any way, or do I need to sit the exams in full? I'm wondering if there is any concept of "credit" towards licensing, so I ...
1
vote
1answer
228 views

What is this RF connector?

And what will I need to mount it in my wall? I'd like to mount it similar to the below images in my wall. Will I need any additional adapters/converters? So to put all my questions in one place: ...
9
votes
3answers
5k views

What is the electrical shock risk of an antenna?

I've seen people refer to avoiding touching an antenna or bare transmission line that might be transmitting. What voltage potentials and currents are commonly found on typical ham radio antennas? Do ...
6
votes
1answer
2k views

What are the most common RF connectors encountered in amateur radio? [closed]

SO-239, PL-259, UHF, NMO, SMA male/female, reverse SMA, oh my! Some of these may even refer to the same thing with different names. Can someone list the most common connector types and show a picture ...
7
votes
1answer
549 views

Is bending the tips of the antenna wires going to affect the effective length?

I'm looking at designs for low cost DIY yagi antennas for a fox hunt, and pondering coat hanger wire and PVC piping. I'd like them to be built by the youth who will be doing the fox hunt, but that ...
10
votes
1answer
208 views

What is body blocking, and does it work with a stock HT on a foxhunt?

I've heard that you might not need a special directional antenna to participate in a foxhunt, that some people are able to use their body to help determine the direction of a signal. How does this ...
7
votes
1answer
359 views

Is FM appropriate for foxhunting?

I'm thinking about an inexpensive way to create a foxhunt kit for youth groups, and am wondering if the cheap dual band HTs could be used. However, it occurs to me that FM doesn't provide any good ...
7
votes
1answer
312 views

Simple cheap foxhunting?

I'm currently looking to do a foxhunt for a youth group, and need to keep it inexpensive and easy enough that it won't be impossible for those new to foxhunting and ham radio, but difficult enough ...
7
votes
2answers
226 views

Is any licensing require to receive in the amateur radio bands?

I'm considering hosting a foxhunt for a local youth group (scouts, in this case), and one of the questions asked was whether those searching for the hidden transmitter need have a license of any sort. ...
12
votes
1answer
5k views

How is the IF for a superhet selected?

There seem to be almost as many choices for the intermediate frequency (IF) as there are superheterodyne receivers and transceivers out there. The ones I have come across are 455 kHz, 452 kHz, 1.6 MHz ...
13
votes
3answers
2k views

Is a vertical noisier than a dipole, and if so, why?

I've had people tell me, anecdotally, that a vertical is noisier than a dipole. Is this true, and if so, why? If it is true: Is this additional noise, such that SNR is degraded, or is the vertical ...
4
votes
1answer
187 views

What would letter T mean in this radio beacon message?

I'm currently picking up signal from a beacon using RTL-SDR and decoding the Morse code on a computer using gMFSK program. The beacon is sending message which decodes as "T DE YU1VHF LOC KN04OO". I ...
16
votes
2answers
1k views

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 [...
2
votes
1answer
1k views

Homebrew 20M SSB receiver design? [closed]

I'm looking for as simple as possible homebrew 20M SSB receiver design. I just want to start listening, but at the same time learn some radio fundamentals. So rather than buying a shortwave receiver ...
15
votes
4answers
12k views

Why do folded dipoles have greater bandwidth than ordinary resonant dipoles?

This is something I've read in passing, but never encountered an explanation of why. For example, Wikipedia says: Another common place one can see dipoles is as antennas for the FM band; these are ...
6
votes
2answers
2k views

80/160m Shortened Dipole Trap Questions

I seem to have forgotten some things I learned years ago for my amateur radio exams. If I am building a 2 band shortened dipole and want a trap between 80 and 160 do I make the trap resonant on 80 or ...
20
votes
2answers
403 views

What is the body of knowledge the U.S. written exams test?

I'm considering getting a U.S. amateur radio operator license. If you want to study to pass a license test, there are many resources to learn the answers to the entirety of the question pool: online ...
10
votes
2answers
612 views

Can an amateur use cellular technologies with SDR?

Software Defined Radio is opening up many new possibilities for amateur digital modes. One family of technologies that interests me is cellular. 2G GSM voice/sms and 2.5G GPRS data has been proven to ...
11
votes
4answers
2k views

Is is possible to operate D-Star from a software-defined radio?

What is preventing a software-defined radio from transmitting the D-Star protocol?
6
votes
2answers
350 views

Is it possible for an amateur to transmit ATSC?

Amateur television has long used the NTSC (analog) television standards to transmit video and audio. Several years ago, the digital broadcast television transition made higher-quality television ...
6
votes
2answers
265 views

Is it possible to overload APRS?

Does APRS have a limited capacity in terms of beacons? What happens when an APRS frequency experiences a large number of packets?
12
votes
3answers
536 views

What is the role of digital data modes in emergency communications?

Emergency operations are typically reliant on voice traffic today. Are digital data modes used at all in emergency operations, and why/ why not? Couldn't data modes be used to pass information more ...
6
votes
2answers
93 views

Does AM demodulation make use of the redundant information in both sidebands to eliminate noise?

XLR microphone cables, for example, make use of the dual channels out of phase to cancel noise by injecting the inverted and non-inverted signal into one end of the cable. Then any noise injected ...
10
votes
2answers
2k views

Buddipole model comparison

Can anyone give me some insight into the different Buddipole models available? They look pretty similar to me except for the sizes. What would make you choose one over the other?
7
votes
1answer
332 views

What is the difference between MFSK64 and MFSK64L?

I noticed this after updating fldigi to decode a Voice of America Radiogram. The only thing I could find in the fldigi changelog was this: ...
9
votes
1answer
120 views

Around the world propagation?

Is it possible to transmit a signal around the world and receive it? Has anyone done it, and how? If not, how could this be accomplished? Assuming a complete path around the world, what kind of time ...
10
votes
3answers
397 views

Using MIMO in Amateur Radio?

MIMO, Multiple Input, Multiple Output, is used widely in commercial data transmission. 802.11n and LTE devices use it to increase throughput, link reliability, and channel usage without increasing ...
4
votes
1answer
117 views

What are the consequences of poor station grounding?

What can happen if I don't properly ground my equipment?
5
votes
3answers
3k views

What type of solder is best suited for radio and electronic use?

Many types of solder are available today, such as acid-core, silver, rosin-core and aluminum solder. What kind should I use for building antennas and radio equipment? Why? From test question: T7D08
6
votes
1answer
826 views

What is spin fading in satellite signals?

Why do signals from satellites experience "spin fading" as the satellite rotates? What are the effects that spin fading has on a radio signal? From test question: T8B09
3
votes
1answer
490 views

Are there any antennas I shouldn't use in my car?

I've heard that "rubber duck" antennas shouldn't be used inside an automobile. What is the reason for this, and are there any other types of antennas that shouldn't be used inside a vehicle? From ...
5
votes
1answer
369 views

Why is coax the most common feedline?

Why is coaxial cable the most common feedline in use? What are the advantages/ disadvantages of coax compared to other feedline types? From test pool question: T9B03
7
votes
1answer
158 views

What are the electrical differences between smaller and larger coaxial cables?

How do different sized coaxial cables, such as RG-58 and RG-8, compare in terms of electrical properties such as loss? Do different cable types have different losses at different frequencies? From ...
10
votes
3answers
375 views

Does modulation affect propagation?

Does the modulation scheme, whether OOK, SSB, AM, FM, a digital mode, etc, affect the propagation of a signal?
6
votes
2answers
124 views

Mobile phone models that contain 2 way radio functionality

Are there any mobile phone models there that contain 2 way radio functionality?
11
votes
2answers
4k views

How do I renew my FCC amateur license?

I have a technician class license, and my license expires in March 2014. How do I renew my license? I received a notification in the mail from W5YI-VEC informing me that I could renew my license ...
12
votes
3answers
3k views

How can I add amplitude modulation to this transmitter?

I recently built this circuit, and could hear a nice full quieting signal on my short-wave radio with a 7.2 megahertz crystal for the 40 meter band. What is the simplest way I could Amplitude ...
16
votes
1answer
18k views

How does a mag mount antenna achieve a ground plane?

I've been thinking for some time about magnet mount mobile antennas and wondering how they establish their ground plane. Consider that many mag mount antennas have some kind of protective coating on ...
8
votes
2answers
491 views

How do sunspot numbers (SSN) affect radio operations?

I frequently hear talk about SSNs in Amateur Radio, and somehow if the number is high, that's a good thing. I just don't really understand what they are, and what they mean, and I'd like to better ...
9
votes
5answers
8k views

Home-brew 10 meter walkie talkies?

"When I was in high school, we had 8 hams at once. (Probably rare) 4 of us built little 10 meter walkie-talkies and had great fun using them on Field Day, hiking or around town. It was ...
6
votes
1answer
9k views

How to determine antenna height for given HF frequency and coverage radius?

I'm planning on setting up a low-HF antenna for near to mid-range contacts. In my particular case, ideally I would like to be able to cover a radius of approximately 1000-1200 km with good ...
2
votes
1answer
78 views

Uni-Directional Simplex repeater?

I understand the reason repeaters can't operate simplex transmitting and receiving at the same time is because they will pick up their own signal. Lets say two people are on different sides of a ...
6
votes
1answer
186 views

How to talk to the ISS

I have a UHF/VHF transceiver capable of transmitting on UHF and receiving on VHF or vice versa on channel mode. I finally got a directional Yagi antenna so reception/transmission shouldn't be a ...
2
votes
1answer
523 views

Tuning an antenna with a SWR meter that relies on output power

In my (new) setup, I will have a solid-state HF radio driving an antenna through an antenna tuner. Both my radio and the antenna tuner have internal SWR meters, of the type that requires you to adjust ...
6
votes
1answer
278 views

1280 MHz propagation out of a mountain valley

I live in a small valley, surrounded on three sides by 200-300 foot ridges. I'm trying to figure out where to place an antenna mast to receive 1280 MHz video from a long range aerial vehicle (20-...
8
votes
2answers
2k views

What determines power handling capacity of an antenna?

I just bought a cheap 1/4-wavelength, 2m. mag-mount antenna. The package says it can handle 50 watts. I can think of three things that could limit the capacity: $I^2R$ losses in the connection to the ...
17
votes
3answers
2k views

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 (...

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