Questions tagged [vhf]

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

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1answer
708 views

What material is best to design a dipole antenna working at VHF frequency? [duplicate]

I need to design an antenna using the tool FEKO. The antenna is supposed to work in VHF frequency and has a gain of around 2.2 dB. What is the best material to use and what are the specifications of ...
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2answers
109 views

Filtering VHF FM on my DTV signal

I've noticed that when I transmit on my HT when I'm watching TV (OTA), the signal drops and the screen goes blank (or digital "static") and then returns when I stop. I've replicated the issue by ...
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2answers
552 views

Troposcatter: really all that bad?

The previous question, Packet Radio at 100 miles and specifically, Phil's answer raised an interesting question: In a 50–100 km distance situation where Line-Of-Sight beams aren't an option for ...
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2answers
148 views

V/U Packet Rate Limits

I'm studying for the General exam and I've encountered some questions about maximum baud rates on various bands. They seem... extremely optimistic. Given the trouble I've had investigating 9600 baud ...
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2answers
218 views

Amplified antenna & typical boombox radio

Can an amplified antenna be connected to a typical boombox radio with a telescoping antenna without damaging the radio?
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2answers
1k views

Are chokes necessary for VHF and higher frequencies?

I am trying to install a VHF/UHF antenna on my truck, and I have been studying everything I need to do that. I keep reading about chokes, in particular here: http://www.k0bg.com/choke.html However, ...
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4answers
2k views

Good Hidden Antenna For 2m

I would like to have an antenna outside for 2 meter VHF use but I do not want it to be expensive and I won't be allowed to put it up if it stands out too much. Does anyone know a good antenna to buy ...
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3answers
434 views

High SWR on a Jeep with Spare Tire Mount

I just installed a spare-tire mount and Browning BR-180 dual band antenna on my Jeep JK. Initial SWR testing show nothing higher than 1.4:1 across both bands so I didn't try to tweak it. Then I put ...
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4answers
861 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 ...
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3answers
9k 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,...
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2answers
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 ...
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7answers
6k views

Is a ground plane necessary for transmitting and receiving with a vertical (monopole) antenna?

I've read the post here: https://electronics.stackexchange.com/questions/77256/why-do-some-radio-antennas-require-a-path-to-ground-and-some-do-not which says The antenna system requires a "ground ...
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1answer
233 views

Looking for documentation on Kenwood NX-700 AFO and DEO Signals

I'm studying the accessory connector (DB-25) from a Kenwood NX-700 radio. It seems that I might use the AFO and/or DEO signals, but I haven't been able to get proper documentation on such pins/signals....
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2answers
70 views

Extracting received power info from teletype like audio

Is it possible to digitally extract received power info (like VU meter perhaps) from and PSK31 audio (or alike), actually the mode for text encoding over audio hasn't been chosen yet and the ...
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1answer
151 views

Radio Modem suggestion [closed]

I need to transmit digital data, from an Arduino, Raspberry or alike, but using VHF band (aprox 150 MHz), would anyone care to suggest a cost effective device to use as transceiver? 10W would be ...
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1answer
149 views

Using 'amodem' to transfer digitally using a UV5R

I reviewed docs for amodem, and it looks like I can send files and possibly other things with this. I should only need to prep my computer as per the doc and set VOX correctly. Does anyone have ...
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1answer
64 views

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 ...
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1answer
187 views

What is the best way to get propagation VHF map for FM repeater?

Is there a way to get a professional propagation map for my VHF 50 watt repeater?
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1answer
4k views

Programming VHF To CB

New to this particular site on StackExchange and new to amateur radio period so bear with me: I'm looking into buying a VHF radio for work related purposes. More specifically the Icom IC-2300H. I've ...
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3answers
3k views

Good FM receiver single-chip IC for simple VHF receiver?

Is there an IC out there that implements all, or most all, of a simple FM receiver in the VHF range? I'm interested in doing some experiments with using DTMF over the air for tele-commands and the ...
8
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3answers
3k views

Antenna for a cramped attic

Brand new Ham. I bought a cheapo UV5 right before I got my call sign. I want to set up a decent 2m/70cm station for starters and I realize that a better radio is important but wanted to knock out the ...
9
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7answers
17k views

Is packet radio possible on Baofeng UV-5R and similar HTs?

I am curious to know if it is possible to do packet radio on VHF/UHF using the UV-5R... I have seen some invasive hardware hacks, but without modifying the radio itself (firmware, hardware) it's my ...
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1answer
231 views

Using RF6886 Power Amplifier for VHF design

I want to use RF 6886 power amplifier for VHF band design. The datasheet doesn't mention VHF design specifications. Has anyone used the PA for VHF design? If yes then please share your designs.
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1answer
149 views

UHF Into VHF Power Amplifier

What would be the result of accidentally applying a UHF signal to a VHF power amplifier? Say a 70cm transmission from a dual-band 2 meter / 70 cm radio into a 2 meter PA, assuming the input power is ...
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2answers
156 views

What type 2 m /70 cm antenna to use when I want to receive a number of spacially separated beams?

So I have a 1.5 m by 1.5 m window. Through it, I have a number of spatially separated ~10 cm wide "beams" coming from local repeaters. It looks something like this: Outside of the marked areas, ...
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5answers
762 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 ...
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3answers
1k views

Improving VHF airband reception

I'm trying to receive VHF airband transmitted from a nearby airport via RTLSDR and having a hard time doing so. Obviously the stock antenna is useless in this situation. I tried building a quarter-...
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1answer
1k views

Balun and impedance matching suggestions for dipole antenna

I'm a newbie who is attempting to build a half-wave dipole antenna that will be located in the rudder of a sailplane. 123.3 MHz is the most important frequency to me, although it's reasonable to ...
4
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1answer
124 views

Pseudorange in VHF band navigation and precision phase tracking

I am thinking on what is the practical limit of precision for VHF positioning system (like currently obsolete and gone "Transit" system). It is well known how GPS receivers calculates pseudorange to ...
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2answers
539 views

Airband VHF antenna challenge

I have a very difficult antenna design/installation challenge. I need to install an VHF antenna (118 to 140 MHz) into a nearly all carbon fiber glider. The radio provides 5 watts and 50 ohm, and most ...
1
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1answer
94 views

Antenna for 6M, or Antenna system?

Here, in VU-land, 6M allocation is from 50 MHz through 54 MHz... which is a fair chunk of spectrum. If I think about a half-dipole antenna; between 50/54 MHz it's length varies by over a foot ... and ...
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1answer
748 views

VHF / UHF - Terrestrial Circular Polarized Antenna

I've been doing mostly HF for the last 20 years and just recently installed a 2m/70cm mobile rig in my shack for base station work. I like to work FM simplex and repeaters when the HF bands are not ...
3
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2answers
440 views

2 meter dipole of work vehicle

I am about to purchase a Baofeng HT. I have one I am thinking of using primarily in work truck. I can't really drill holes or have antenna be too obvious. On Amazon I found a 2 meter 70cm 2m dipole....
6
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2answers
353 views

Weather Imaging with NOAA satellites - legal?

I would like to build an antenna for receiving NOAA weather satellites. They're receivable at around 137.5 Mhz. I'm a total new to amateur radio stuff. I know that it's not legal to communicate as ...
2
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2answers
387 views

Replace directional antenna by fixed antenna

Given the following specs of a directional antenna: ...
2
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4answers
168 views

Colorado to Ohio with UV-5R

My brother (in Ohio) just passed his Technician test. We both have UV-5R equivalent radios. I have my General (in Colorado). Without physical modifications to our radios, can we have a QSO? I've been ...
2
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3answers
126 views

Identifying Local Signal

I've been monitoring a signal locally on 159.150mhz (which is allocated for "Civil Defense"). I believe that this frequency is for the local tornado sirens and I would like to be able to decode the ...
9
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2answers
2k views

Marine VHF whip antennae - what are they?

For marine VHF (156~162 MHz), the most commonly used antenna is a 1/2-wave dipole or a collinear array in the form of a fibreglass rod. Collinear arrays are used to increase gain in some antennas. ...
8
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1answer
723 views

Is a modded Yaesu FT-270r acceptable to use on MURS frequencies?

I am a bit new to the radio scene, so excuse me for any ignorance that may follow. I saw on a website that you could mod the Yaesu FT-270r so that you can increase its transmission range outside of ...
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2answers
4k views

Tuning/trimming a ground plane antenna

I've built a ground plane antenna with a 19.5" vertical and 4 20" radials. Currently, at 147.135 MHz my SWR is 3:1, clearly not ideal (and even bad for the transmitter!). I'm reluctant to start ...
2
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2answers
2k views

Which Frequency Band(VHF/UHF) is most useful for satellite in MEO?

I want to get to know about the satellite communication at 8000-10000 km, During that, I come across the VHF and UHF. In that I am facing problem for deciding the frequency band for communicating with ...
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0answers
229 views

How can I connect a CW keyer to my Mac and transmit CW on VHF? [duplicate]

I currently have a Kenwood TM-V71A 2m/70cm transceiver that I would like to connect to my Macbook to transmit morse code, using the cocoaModem software. Aside from the cables needed to connect the ...
2
votes
1answer
420 views

VHF antenna / receiver suggestion for a UAV

I am currently working on a student project that involves having a UAV fly an orthogonal path over a series of transmitters -- taking in data (through an arduino-based system for data processing). ...
6
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4answers
2k views

Why can't VHF / UHF be used with ionosphere reflection?

HF radio can be reflected by the ionosphere, giving very long range communications. Why can't VHF / UHF used with ionosphere reflection? Is it due to the attenuation of the atmosphere over that ...
3
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2answers
8k views

Looking for a UHF / VHF transceiver for PC.`

I am looking for a simple UHF / VHF transceiver that I can plug into my PC via USB and be able to RX/TX on one channel, using the built in mic... Maybe even record the RX from the freq. Everything I ...
5
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2answers
312 views

BAOFENG UV-5R for cubesat communication on lab, does it work?

Here we have a cubesat which operates in VHF/UHF. Communication with it (from a ground station perspective) is done with an Icom Radio. Would it be possible to replace it with a cheaper BAOFENG?
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4answers
384 views

Will Icom HM-133 work on IC-2800H

I have been having problems with the knock off of Icom microphone so I figured I would bite the bullet and get a new Icom microphone, since the original is out of production. I found that HM-133 looks ...
2
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2answers
264 views

Using square loop VHF antenna for two different stations/frequency?

I'm using a square loop antenna on the rooftop of approximately 15 square meter area. I use it to communicate with a group of mobile VHF radios using a station room. Right now I'm planning to build ...
10
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2answers
623 views

Getting Started with Digital Modes on VHF on Linux

I am interested in learning about digital modes using 2m and Linux. I have a couple of older 2m rigs (HTX-212 and an old Yaesu) with no additional hardware, like a TNC. What current resources exist ...
3
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1answer
147 views

Transverter common versus split-if connections

I have a radio (Flex-1500) that has low level transverter outputs. They can be configured as either a common or split-if. I also have a DEMI transverter that can easily be wired up for common or ...