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Questions tagged [uhf]

Ultra High Frequency is the frequency range 300-3000 MHz.

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17 votes
4 answers
19k views

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,...
William's user avatar
  • 803
9 votes
5 answers
61k views

On which of these frequencies can I transmit without a license?

I have a Baofeng UV-5RA, and I need to know what frequencies on the "channel mode" (what the lady says when you press the "V/M" button on the radio) don't require a ham license. I am in Philadelphia, ...
SPC Philadelphia's user avatar
20 votes
10 answers
99k views

What antenna on a BaoFeng UV-5R Pro will give me better reception? [closed]

I am happy with my BaoFeng UV-5R Pro but the local UHV VHF repeater and simplex reception is terrible, even for contacts less than 50 kilometers. I assume that it's because the rubber-ducky antenna on ...
Warren  VE3WPX's user avatar
13 votes
2 answers
1k views

Direction finding: How to find a stuck FM transmitter on 70cm?

There's a blank carrier on a 433 MHz FM voice frequency here. How should we go on about finding the transmitter's location? Practical procedure? Could be somewhere downtown.
oh7lzb's user avatar
  • 2,391
11 votes
4 answers
2k views

How does VHF/UHF propagate beyond the expected (radio) horizon?

I am not asking about the fairly well-known effect of the earth "appearing less curved to radio waves" that are otherwise still essentially line-of-sight, but a deeper arcanum: In the ARRL Antenna ...
natevw - AF7TB's user avatar
10 votes
2 answers
1k views

Moon->Earth 433MHz link achievable digital bandwidth

Let's assume we have the following situation: Transmitter on moon orbit (distance from earth ~400'000km), around 433Mhz. Transmitter power 1W, antenna gain 10dB, circular polarization. Steered to ...
BarsMonster - R2AYN's user avatar
9 votes
1 answer
458 views

Hardened UHF Antennas

Minuteman missile silos used an interesting hardened UHF antenna. What kind of antenna is this? Does anyone have a drawing with a cross section? Edit: Jay Moore added a picture to a different type of ...
Olg's user avatar
  • 91
9 votes
4 answers
18k views

2m or 70cm FM mobile radio for digital mode operation

Are there any 2m and/or 440cm FM mobile radios that have audio inputs for supporting digital modes, like PSK31 or SSTV? I have a Rigblaster that I use with my HF radio so I could get a mike cable and ...
Kevin Hooke KK6DCT's user avatar
7 votes
5 answers
3k views

Can 433 MHz amateur bands be used for ISM purposes?

From this poster, http://info.tek.com/AM-RSA306-Spectrum-Poster.html, it indicates that a band around 433 MHz is globally-accepted for use as an amateur band. Can this same band be used for ...
plu's user avatar
  • 173
6 votes
3 answers
869 views

2.4 GHz Antenna for RC copter

What is the best omni-directional antenna design for any RC flying objects? Many times I've lost signal and my copter falls due to lost signal. (Using default antenna). Since the receiver and ...
Bianca's user avatar
  • 175
3 votes
2 answers
789 views

How does the antenna noise temperature vary with antenna elevation?

I'm using a 14 element cross Yagi antenna in my system. For my link budget calculations, what antenna noise temperature should I consider? How does this vary with elevation?
heisenburg007's user avatar
3 votes
2 answers
6k views

Licensing a group of BaoFeng BF-888s in the UK

I've purchased a couple of BaoFeng BF-888S's for personal use with friends. I've been told these radios can't be used legally without a licence and given the usage, I doubt I could faithfully even ...
lewis's user avatar
  • 133
3 votes
3 answers
923 views

Why is VHF better than UHF in this situation?

One of the sample questions for the British foundation level test is: An amateur has the choice of VHF or UHF for a particular contact of some 25km. Which statement below best describes his choice? ...
Pablo Fernandez's user avatar
2 votes
0 answers
129 views

Biconical antennas - bandwidth and installation

I am posting this question (and its related question) here because of the unique expertise that Ham Radio Operators have as it relates to antennas. I'm a newish Ham and really appreciate your help ...
FontFamily's user avatar
2 votes
5 answers
1k views

What would be the easiest and most cost effective ground system for a startup UHF/VHF station

I just passed both my Technician and General Class license this past weekend, and am now contemplating my first station. To get my feet wet I'm planning on getting a Yaesu FT-7900R Dual band Radio ...
Korky Kathman's user avatar
1 vote
2 answers
192 views

Repeating UHF Handheld via UHF vehicle transceiver

I have recently taken on programming radios for my workplace in Chicago, IL. We have an old base station (Kenwood TK863G-1) that I wanted to know if it would be possible to use as a repeater similar ...
Fireant456's user avatar
1 vote
1 answer
402 views

Double Cross Dipole antenna for 437 MHz don't tune

I'm building a Double Cross Dipole antenna for 437 MHz to be used with a SDR receiver for CW cubesat. The idea is to follow this "classic" paper from Gerald Martes, KD6JDJ. I tuned every single dipole ...
Carlo IU2KQB's user avatar
1 vote
1 answer
125 views

Repeater for 1/4 square mile campus

I am a noob to a lot of amateur radio and I am investigating and planning a repeater setup to be installed in my workplace. We are on a hospital campus in Chicago, IL and have many tall buildings ...
Fireant456's user avatar
1 vote
2 answers
1k views

GMRS not transmitting within a half mile

I recently got my GMRS license from the FCC, and I wanted to try out a couple radios for hiking and emergency communication. I have two tenway UV-5R pro radios (these do have an FCC ID) that are set ...
user16052's user avatar