Questions tagged [vhf]
Very High Frequency is the frequency range 30-300 MHz.
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Using Aviation VHF radio on different frequencies
I have an old Icom A-5 aviation handheld with a frequency range of 118.000-136.975 MHz on top of WX, AM, and FM receive functions. Is there any way with little modification, or a simple static build ...
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Optimizing Half-Duplex Sequencing: Consolidating RF and Power Connections with Bias-T and VOX
I've successfully implemented a half-duplex sequencing mechanism, which I've illustrated below. The outdoor components are represented in green. In my current setup, I utilize a PLC to control both an ...
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Monopole antenna with no ground connection
I have a SDR device and have a question about using a monopole antenna with them, but the question could be applied to any device which uses an antenna.
SDR comes prepacked with a monopole antenna ...
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Pulsing static on 6m
Located in Illinois, US, I recorded this http://loami-windmill.com/sounds/6m_noise.m4a on 28-June-2023 at 1603 UTC on 50.074MHz USB. The static has regular "pulses" where it gets slightly ...
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Creating a single feed wearable wire antenna
When I was deployed, our commo guys gave us wire antennas we could thread through our body armor (through the MOLLE loops).
These antennas were just lengths of 50Ω coax that had the insulation ...
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UnUn for VHF and UHF
Is it possible to build an UnUn for VHF or UHF like in HF?
Goal is to use a simple endfed wire or piece of metal as an antenna.
EDIT: I meant "endfed halfwave".
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Is the noisy spectrum from 20MHz to 330 MHz normal?
I have recently been testing some VHF/UHF antennas for reception in my Lab, and have noted something I could not explain. Following are the spectrum plots captured on our R&S FSV spectrum analyzer,...
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A new ham should start with Digital or Analog Portable Radio?
I am interested in acquiring two portable radios to talk between a family member and me (both new hams), e.g. when we go trekking in a National Park or to communicate in the same city. We used PRM ...
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How does nitinol shape memory wire work as an Antenna in 60 MHZ whip antenna?
I'm trying to make a body whip antenna for some friends of mine running at 60 Mhz at 10 W power. We are in the military, and we are trying to make an antenna that can be routed through our gear to ...
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Portable indoor VHF antenna for SDR
I want to make / buy VHF antenna that can meet the requirements below:
Portable (easy to install and transport).
Indoor (I want to install the antenna at a windowsill).
Low noise level, no (or not ...
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Why are VHF radios so much cheaper than HF ones?
Why do VHF-UHF radios tend to be cheaper than HF ones? There are expensive VHF radios and relatively cheap HF ones, but finding a cheap VHF radio is much easier than finding a cheap HF radio. Why? ...
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When to use TSQL vs TONE for a (2m) repeater?
I'm trying to understand when to use TSQL and when to use TONE in the configuration of a repeater. I got a repeater file to import into my radio from http://www.dstarinfo.com/repeater-list.aspx and in ...
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How to build the best bang for yhe buck uhf vhf antenna or should i just buy one [closed]
Help with antenna build what makes up a great antenna what can I use for elements and would a dush network dish be good reflector and how to wire the elements like the copper to one side and the ...
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ISS repeater on a Baofeng?
I know people have RECEIVED a signal from the ISS on a Baofeng UV-5R, but I'm interested in TRANSMITTING. I'm going to be using a Baofeng UV-5RTP (basically an 8W UV-5R) with a Nagoya NA-771 that ...
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1/2 wave dipole instead of 1/4 wave + ground plane
I have a transceiver operating at 150MHz using a 1/4 wave vertical whip and horizontal ground plane at 90 degrees.
My end user doesn't like the antenna sticking up in the air (trip hazard) so I'm ...
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How do antennas over 1/2 wavelength work?
I've been told countless times that an antenna should be 1/4, or 1/2 wavelength. That increasing this size to a higher multiple of 1/4 will work, but it will distort the radiation pattern to include ...
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Design of an LNA housing box for a UHF/VHF satellite ground station
I'm currently designing a waterproof metallic case to house LNAs, power cables, and RF switches for a UHF/VHF satellite ground station. As shown in the diagram below, the antennas are connected to an ...
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Using threaded rod for VHF radials
I've been thinking about building a VHF antenna using stainless threaded rod for the ground plane's radials to mate with a hub I already have. My theory is that will make life easier than trying to ...
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YouLoop antenna for amateur satellite reception
I recently learned about the commercial YouLoop antenna and it seems to be quite simple to set up. They said it was possible to receive satellite signals on amateur VHF (e.g. NOAA and other CubeSats ...
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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 ...
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Is SSB and FM voice considered TDD or FDD (and what are TDD/FDD)?
We are looking at the Qorvo QPL9547 LNA and the datasheet notes:
For TDD Applications: R1 = 0Ω & R2 = 100K
For FDD Applications: R2 = 100K ‘OR’ Pin 6 tied to ground. R1 = DNP/Omitted
This will ...
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Automatic identification system (AIS) on aprs.fi - Long Rx -> Tx distances
I've been looking into some of the info available on aprs.fi, which also makes available AIS data, but most of the reports I see have such large Rx->Tx distances that I'm not clear on how things ...
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How do vehicle anti-theft trackers work on VHF? [closed]
I'm looking in to vehicle trackers, the kind that allow police to track stolen cars such as Tracker (UK) or LoJack (US), and I can see there is quite a lot of variants out there.
The common consensus ...
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How to choose antenna "pigtail" pragmatically?
I'm starting to tinker with an RTL-SDR (generic, and cheap, so nothing fancy in any respect, hence the "pragmatic" in my question title).
It's clear that the antenna provided (about a foot ...
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Why do operators mention the band when calling CQ on phone?
I'm a new-ish ham, licenced for about one year now.
Within that year I've heard a lot of CQ calls from other hams on phone (both HF and VHF), and it seems that a large portion of hams routinely ...
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How much dB gain do you need from an LNA in front of an antenna for great low-signal reception from satellites in the 2m and 70cm bands?
We are building a multi-stage LNA for a TR module we are building in the 144MHz and 440MHz range. This LNA we are considering (Qorvo QPL9547) provides about 22dB gain in the 2m and about 27dB in the ...
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What is proper procedure for asking for "distant" contacts on 2m FM on simplex?
As a new ham, just for fun, I'm planning to hike up to the local high point (which while not high in an absolute sense does have a commanding view of the surroundings) with my 5 watt FT-4XR and a slim ...
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Why do people say, "get a nickel," on repeaters?
Sometimes, I'll hear someone say "wait a moment, I'm getting a nickel," and then drop the carrier only to resume talking. Why?
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Is it possible to convert a euro Yaesu 991a to US band plan?
I bought a euro Yaesu 991a . The vhf/uhf band plan is severely limited for use in the US . I have tried the button presses as shown for the earlier 991 and the service mode works to open the frequency ...
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Is testing SWR *practically* less important for 2m/70cm than HF bands?
Totally new amateur operator and I've noticed that a lot of material e.g. Your Tube videos, blogs, forums when discussing metering VSWR mainkly seem to be talking about HF bands. I also see fewer VSWR ...
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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 ...
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Trying to identify and understand this antenna design - ground independent dual band vertical
This is the insides of a common dual band antenna 2m/70cm, made by diamond or nagoya.
its generally labelled as: 1/2 wave radialless (144MHz), 2 x 5/8 wave radialless (430MHz)
Its meant to be ground ...
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Why am I receiving a local tv channel on a CMB frequency
I am using a simple Baofeng H6 dual band radio and I programmed weather channels.
Well, on frequency 161.77500 I am actually picking up WGN, a local tv network.
This frequency should be reserved to ...
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Use (TV?) Log-Periodic antenna for VHF
I found this old log periodic antenna that I assume was from a TV. Could I, or how would I, use this on the amateur radio bands? My main focus would be VHF, with UHF being secondary and HF would also ...
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Hatch Mount Antenna Selection - Dual Band 2m/70cm
I just bought a Diamond CP-5NMO hatch/lip mount and intend to put it on the hatchback lip of our 2018 Subaru Forester and, if it will fit, another one on our 2019 Kia Niro EV. I understand that hatch ...
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What length and number of radials should be used for a dual band vertical whip backpack antenna?
The Situation:
Very new Ham
I have a 2m/70cm 48" Abree whip antenna, originally designed to be connected directly to an HT
I would like to mount this antenna to the side of my hiking backpack, ...
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Is the Boom Strictly Necessary in a Vertical Dipole?
I'm planning to build a vertical dipole for 4m and a club member pointed out that my design needs to allow for a boom that should be at least a 1/4 wave long. Why does a vertical dipole need a boom ...
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Heat-shrink as dielectric for bazooka balun?
I'm intending to make a sleeve balun (aka bazooka) for 2m, but rather than keep the lossy coax jacket as a dielectric (I have some RG58), was considering to remove it and replace it with heat shrink ...
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Ground-Plane radial sizing, is there such thing as too long?
I'm just trying to make sure I understand the theory correctly.
I have some triband VHF/UHF/800MHz antennas, I need to mount on a tower so I plan on using a "mobile to base" conversion kit. ...
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Any reason not to choose a discone antenna over a Wide/ MultiBand mobile antenna for TX/RX operations
We are setting up a all-band radio in an emergency com center that's intended most for amateur band use, but since its' for emergency use will also be used in the public safety bands; (150-170)MHz, (...
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how does this collinear antenna work?
I was looking for a cheap and easy to build 2M/70cm vertical. I found this: http://vk2zoi.com/articles/dual-band-high-gain-flower-pot/
Here are the plans to build it:
But I don't really understand ...
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Handheld multiband radio for a ham firefighter?
I live half a mile from my volunteer fire station. We are toned out on a VHF frequency by a neighboring municipality, and we provide mutual aid for their fire department that is toned out on an 800-...
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Optimal length of HT antenna for VHF UHF and diminishing return
I see folding antennas of various lengths that people are using for for their HT. My question is about the optimal length. I know it may "depend" on many factors so let me know if I need to provide ...
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Extremely strong QRM on VHF?
I don't usually operate in 2 m, save for FM satellites. I usually go to a nearby park when I do this, for better view of the horizon. But I tried working them from home for the past couple of days, ...
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144/430 MHz antenna on 155 MHz?
We have a local radio shop that started selling us Relm P150s with a high gain 9 inch antenna, and those are ok.
He also has thrown in longer 15 to 14 inch dual band antennas saying use those in ...
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How should I stack these folded dipoles?
Looking to stack these 8 folded dipoles on my 100ft tower.
I can not find any information whatsoever on these. I have 4 consecutive serial numbered boxes.
Bluewave Marathon
BME139FN1H0
138 - ...
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Malicious interference to repeater
Our local repeater is severely sabotaged by unknown parties. For example, broadcast radio transmissions are repeated. Other times someone will send a transmission, when a qso is in progress. Local ...
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Wide band TX capable band-pass filter for VHF and Airband
I want to share the same antenna for VHF (TX/RX 144-148 MHz) and for Airband RX-only (116-136 MHz).
I live on a very congested area where filter is a must, so I'm looking for the best solution for my ...
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What VHF & UHF frequencies are important during an emergency?
If something bad goes down (state-wide or nationwide), what frequencies should I be tuning into?
I did see this answer, but I have a BaoFeng UV-82HP which cannot do HF at all, so what are my options?
...
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High Altitude Balloon Antenna Design
I'm designing a weather balloon with a club at college. We want to build the antenna from scratch to learn more about antennas but are at a loss as to which antenna design would actually work for high ...
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