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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?
8
votes
1answer
373 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
130 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
452 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
139 views

What are the consequences of poor station grounding?

What can happen if I don't properly ground my equipment?
5
votes
3answers
4k 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
940 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
518 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
399 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
172 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
401 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
126 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
5k 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 ...
17
votes
1answer
23k 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
522 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
9k 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
10k 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
86 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
211 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
583 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
296 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-...
9
votes
2answers
3k 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 (...
4
votes
1answer
787 views

How can I generate a list of APRS IGates on 30m?

I am investigating using a Tiny Trak 4 with my portable HF radio to self-spot on SOTA activations via APRS on 30m. I usually self-spot via a text message. When I don't have any cell coverage, I can ...
5
votes
1answer
286 views

What is a shallow/deep QSB?

Probably all amateurs recognize QSB as the q-code to represent 'fading'. I recently encountered the terms Shallow QSB Deep QSB A quick google search failed to yield fruit; What do the above terms ...
7
votes
2answers
767 views

Store-and-forward capable satellites in operation?

The amateur satellite community used to have a small fleet of pacsat satellites (AO-16 and friends), which were capable of store-and-forward message passing: you could upload messages to the LEO ...
10
votes
2answers
94 views

Where on the web can I find a calendar of upcoming contests?

For years, I have been using SM3CER Contest Service for HF contests. It is always good to have a backup, so I am looking for more or better. What do you recommend?
8
votes
2answers
358 views

Have hams ever used (clusters of) geostationary satellites as passive microwave reflectors?

A number of geostationary satellites are quite large and/or appear in clusters. Moreover, many of them have large reflectors pointing to Earth (e.g. satellite TV sats). Finally, these satellites are ...
6
votes
1answer
1k views

Are there easier ways to make traps than coax and plastic pipe?

I recently built an antenna for my attic inspired by http://degood.org/coaxtrap/. I found making the coax traps very time consuming and frustrating to tune. I got to thinking about 3D printers, and ...
2
votes
1answer
140 views

How would one plan to setup an amateur radio station on Antarctica?

Just what the title states. For instance The extreme temperatures could kill any power-supply such as an SLA A dipole antenna may collect ice and break Vostok Station holds the record for -89C; ...
9
votes
2answers
330 views

How does the South Atlantic Anomaly affect propagation in the HF bands?

At ~34ppt the Southern Ocean is significantly less saline than other major water bodies (Arctic Ocean excluded). The Southern Continent also shares proximity to the South Atlantic Anomaly - where the ...
12
votes
4answers
1k views

Amateur radio in an EOC?

Consider a small town's emergency operations center. While there are amateur radio operators involved, they primarily work for government or public safety, and there is no active ARES participation. ...
9
votes
2answers
2k views

Cleaning relay contacts?

I have an old transceiver. I have a problem where ocassionally the received signal will drop out when switching from transmit to receive. I've narrowed it down to the transmit/receive relay. When ...
9
votes
2answers
243 views

How are multiple-operator contest stations with one radio usually operated?

I am the president of a small school club. We plan an participating in the ARRL SSB Sweepstakes this weekend, which is our (new) club's first real multi-op contest effort. How do multioperator/club ...
8
votes
1answer
244 views

What is a good way to bench test a mesh network?

I've been experimenting with some 2.4ghz based mesh networks similar to http://hsmm-mesh.org/. I'd like to have something on the bench where I could simulate roving between nodes, and create hidden ...
5
votes
2answers
1k views

Can antennas have reverse harmonics

I know antennas can have 1/4 wavelength, 1/8th etc. but if you are operating from UHF bands, can the antenna be lets say twice as long?
2
votes
3answers
1k views

Airband Jammed on Yaesu VX-6R

I am an owner of a Yaesu VX-6R. This radio works great on amateur bands. As a glider pilot I often need to hear the frequency of the local airport. I would like to find out whether this radio is ...
13
votes
4answers
3k views

Handheld Dipoles

A problem with handheld devices is poor grounding. I read from someone else's question that dipoles don't need a ground. Why don't they make little handhelds with two antennas instead of one, or a ...
6
votes
1answer
122 views

How to ground with little surface area?

Let's say I have a very small device, like an RC airplane, which transmits information as well as receiving commands for control. The body is made out of non-conductive foam, therefore not much ground ...
6
votes
4answers
4k views

How to build a remote control unit that works on amateur radio frequencies?

The only remote control units I have used before was those little cheap 27Mhz puny range cheap units. I would like to build some sort of RC unit, which has a range up to 1km line of sight. I have a ...
3
votes
1answer
1k views

Is the Wilderness Protocol dead? [duplicate]

I have read the description of the Wilderness Protocol. I have attempted to use it (only after the 4 min emergency window) on multiple occasions at multiple wilderness locations and never received a ...
17
votes
1answer
340 views

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 ...
7
votes
1answer
129 views

Is there a standard data format for station/channel/band information?

Does there exist a de facto standard data (file) format, or even several common formats, for representing information about radio stations, channels, and/or bands? I am writing software which would ...
17
votes
4answers
102k views

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 ...
13
votes
12answers
14k views

How can I safely transmit without an antenna tuner or SWR meter?

Just what the title says. An Antenna Tuner, henceforth AT, is almost a de facto piece of equipment in a shack; working the bands without one is tantamount to leaping off the diving board into a ...
8
votes
1answer
310 views

Why do USA transceivers limit transmit to 430-450MHz?

The FCC table of frequency allocations clearly states on page 27 that the Amateur allocation for 70cm is 420-450MHz, but I've seen a lot of transceivers that limit transmit to 430-450MHz. Why is this?...
7
votes
2answers
517 views

License upgrade - retake required?

It's been more than a year since I passed my Technician and General exams and obtained my license. If I were now to go for my Extra class license, would it simply be a matter of taking and passing the ...
18
votes
3answers
4k views

SDR sampling bandwidth - do the bits per sample matter?

I'm looking at data converter chips for a homebrew SDR design, and I see that I can choose not just the sampling frequency, but also the bits per sample. Obviously the sampling frequency has to be ...
28
votes
5answers
32k views

Can I reduce RFI/noise at the antenna?

Recently, the power was out in my neighborhood for an extended period of time. I fired up my HF rig using battery power and was amazed at the lack of noise across the HF bands. When the power grid ...

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