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10 votes

antenna in the rain

The antenna itself won't be significantly affected by the water. However, waterproofing the coax connection is essential. If this is not done, water will creep inside the coax by capillary action and ...
9 votes

How would you get an "I'm alive" message to family in another state using amateur radio?

The ARRL NTS (National Traffic System) is the method you would use to send messages to anyone anywhere in North America and in concert with other traffic systems to many parts of the world. NTS has ...
  • 2,898
9 votes
Accepted

How would you get an "I'm alive" message to family in another state using amateur radio?

When establishing emergency communications in a disaster, the natural choice of band is one that will allow you to communicate out of the disaster zone. Given the scenario you describe, a massive ...
  • 8,972
7 votes
Accepted

Is using an HT and walking considered mobile?

Insofar as there is an agreed-upon definition of the term “mobile” (and “portable”, which is closely related/confusable and so I'm covering it here), this is how I have most frequently seen the terms ...
  • 23.4k
7 votes
Accepted

Should I ground my radio to the chassis or battery for a mobile install?

There are two reasons for the advice to run direct to the battery: Minimize the area enclosed by the power connections. This reduces both interference picked up by the wiring, and inductance (which ...
  • 23.4k
7 votes
Accepted

When and why does the size of a ground plane or radials matter?

Perhaps consider that the objective of the ground plane is to present a low impedance. At the feedpoint, the hope is to have all the current go into the antenna, and none of it on the coax common-mode....
7 votes

Is Part 90 certification something an amateur radio operator should look for in a radio meant for amateur use?

Part 90 certification is required for radios used in the USA in the land mobile services - often called commercial radio. No such certification is required for the amateur radio service. The closest ...
  • 18.3k
6 votes
Accepted

Amateur Radio for a Nomad

The only thing you need to do is make sure you can receive mail at the mailing address on your license, because that is part of the obligation of holding a license. It doesn't have to be your ‘...
  • 23.4k
6 votes

Amateur Radio for a Nomad

The relevant regulation is §97.23: Each license grant must show the grantee's correct name and mailing address. The mailing address must be in an area where the amateur service is regulated by the ...
6 votes

How would you get an "I'm alive" message to family in another state using amateur radio?

Send an HF-E-Mail addressed to your familymembers using a system like WinLink 2000 (http://www.winlink.org). It uses Radio Message Servers (RMS), which provide a bridge between the Central Message ...
  • 61
6 votes
Accepted

What size is the Kenwood TM-D710 panel mounting bracket?

This image of the bottom side of the bracket was taken with a flatbed scanner. The depicted dimensions were taken separately using a caliper, not by measuring on the image. The white inner area is the ...
  • 23.4k
6 votes

antenna in the rain

Water has a drastically different relative permittivity $\varepsilon$ than air (water: ca 88, air: pretty much 1); it is, however, pretty non-conductive, just like air (being distilled and all). In a ...
6 votes
Accepted

Better SWR bandwidth

A low SWR bandwidth is a consequence of shortening the antenna for mobile use. SWR bandwidth is related to the antenna system's Q factor, the ratio of energy stored to energy dissipated per cycle. A ...
6 votes

Need batteries for backpack operation

I used LiFePO4 (read: Lithium Iron Phosphate) for my dad's FT-891. The big advantages of LiFePo4 are: Very power dense, almost as much as Li-Ion, IIRC twice as much Wh/kg than Lead-acid Extremely ...
  • 1,179
6 votes

UHF 70cm unlicensed use

The likelihood that your radios are being operated legally is small in my opinion, at least if you're in the US. The only entirely unlicensed frequency in that section of the spectrum that I'm aware ...
5 votes

Frequencies as 5 digits and 6 or 7 digits

It depends mainly on the culture using the frequency, the frequency value itself and how important is each part of the frequency. In the lower frequency ranges, it's not uncommon to give the ...
  • 2,725
5 votes

Can RF work while it's in motion?

The effect of motion is to cause Doppler shift in the received signal. This changes both the carrier frequency and the symbol rate. However, because the speed of propagation of the wave — an ...
  • 23.4k
5 votes

OK for S/RF light to be illuminated at engine idle?

If your car uses petrol (gasoline) rather than diesel, then the ignition system can potentially generate a lot of noise because of the high-voltage system used to generate the sparks that ignite the ...
  • 4,429
5 votes

What wireless communication technologies can travel long distances with a high bandwidth?

All kinds of digital microwave technologies can do this, including WiFi. It takes a good antenna location high from the ground, and good antenna gain / transmit power. Commercial wireless ISPs do it ...
5 votes

How to log contacts when mobile?

In the USA there is no longer any legal requirement to keep a log. Many HAMs log HF contacts often for use in contests or applying for various awards. There are a few contests and awards for VHF / ...
  • 1,298
5 votes
Accepted

How to figure out my car battery's capacity?

There are many ways to do this. My favorite and I would assume you have these items in your shack. Most inverters have an automatic low-voltage disconnect feature. It makes a beeping sound and stops ...
  • 216
4 votes
Accepted

Starter package?

I am a new Ham (K7BED) and only transmitted for the second time, today. I want to say to purchase a low cost HT (such as a Baofeng UV-5/5R/5RA/whatever) but that was what I did and it was a waste of ...
4 votes
Accepted

How to eliminate alternator whine?

The most important and simplest thing you can do to eliminate alternator whine is run a separate set of power cables directly from the cars battery terminals to the radio. Making sure you include the ...
  • 56
4 votes
Accepted

Connecting radio in parallel with inverter in mobile set up

There are two things I like to highlight: 1) You are thinking of putting the radio in the same glove box as the inverter; hence you may need extra ventilation/circulation to ensure neither equipment ...
4 votes

How do you keep your vehicle clean with a mobile antenna?

They do make weatherproof caps for NMO and SO-239 antenna mounts. I've used those for years. I pull up to the wash, take the antennas down and stow inside, and put the caps on. Post wash, reverse ...
4 votes

Tiger Tail + capacitive coupling... what's the interaction?

I tested your make/model antenna and others in various configurations with and without a tiger-tail on a small 2m HT with results in this article. Here is the money graph... Needless to say the extra ...
  • 590
4 votes
Accepted

Noticeable difference between trunk and roof mount?

Yes there is a difference but it tends to have more to do with the pattern and efficiency of the antenna than anything else. When an antenna is mounted on the trunk, the roof line and the occupants ...
  • 18.3k
4 votes
Accepted

Is there a special term for amateur transceiver speakers or anything that makes them different from any other kind of speaker?

Is there something that makes amateur radio speakers better or different than any other kind of unpowered speaker of equivalent wattage and impedance? Some may have audio filters, headphone jacks, or ...
  • 23.4k
4 votes
Accepted

What are the maximum possible speeds of download over Amateur Radio frequencies?

maximum rate There's no upper boundary really other than SNR. There's no general number. There's what information theorists call channel capacity, which simply relates the amount of bits per second ...
4 votes

GMRS not transmitting within a half mile

First, the legal issue: in the US, it's not legal to transmit on GMRS frequencies on a radio not type-accepted for GMRS. Having an FCC ID doesn't mean that a radio is type-accepted for GMRS; UV-5Rs ...
  • 8,972

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