Questions tagged [vhf]

Very High Frequency is the frequency range 30-300 MHz.

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13 votes
2 answers

Is there an optimum Antenna Feedline Length for mobile installations?

I bought a ham radio antenna mounting kit for my car that includes ~16' of coax. One end has a trunk lip NMO antenna mount, the other end has a re-solderable PL-259. I asked the sales person if it is ...
BenSwayne's user avatar
  • 681
17 votes
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,...
William's user avatar
  • 803
20 votes
10 answers

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
11 votes
4 answers

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

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
4 answers

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
6 votes
1 answer

Kenwood TH-D72A: what's the difference between Tone and CTCSS?

Kenwood TH-D72A supports 3 types of tone: Tone, CTCSS and DCS. What is the difference between Tone and CTCSS? As far as I know CTCSS is basically a continuous transmission of a given low frequency ...
Aleksander Alekseev - R2AUK's user avatar
4 votes
4 answers

Is a copper J-Pole antenna better than a Slim Jim for transmitting?

I live in a fairly sheltered valley but there are several hill-top VHF repeaters that I can receive very well. However the one repeater in particular I want to transmit to, I can't reach well. I ...
Brad McCarty's user avatar
3 votes
3 answers

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
3 votes
1 answer

Shifting Frequency of a VHF Crystal?

I have a boatload of 165.550 MHz Regency 10.7 MHz IF Crystals. I need them to resonate for 165.500 MHz. How can I shift the crystal frequency down 50 KHz without opening the 'tincan' and messing ...
Station51's user avatar
3 votes
2 answers

VHF Balancing, necessary? Methods?

This is a question about power dissipated due to radiation and ohmic heating caused by common mode current in the coaxial shielding, specifically at VHF frequencies. When a balanced antenna (such as a ...
elplatt's user avatar
  • 160
2 votes
0 answers

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
1 answer

VTS messages vs AIS

When arriving in a port, complementary to her AIS signal (encoded VHF message) it seems that the vessel also has to emit a voice message on a predifined VHF frequency to identify herself as part of ...
Go4It's user avatar
  • 121
2 votes
2 answers

Is my low-power VHF transmitter dangerous?

I use a Raspberry Pi for transmitting FM on 107.9 Mhz. It uses square waves and has a power of approx 0.085 Watts, but just to be safe: If I have a 1 watt transmitter approximately 1 metre away from ...
user avatar
2 votes
5 answers

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
2 votes
2 answers

Replace directional antenna by fixed antenna

Given the following specs of a directional antenna: ...
KcFnMi's user avatar
  • 353