Questions tagged [uhf]
Ultra High Frequency is the frequency range 300-3000 MHz.
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Useful Search Terms To Find Crossband-Capable Mobile Transceiver
Referring to Building a portable event repeater what criteria should I use to search for a crossband-capable transceiver? Specifically, what terms do I use with places like Ham Radio Outlet, Gigaparts,...
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Trying to find an IC for RF Tx Rx switching
I want to built a T/R switch for 75W at 433 MHz. I found ICs to not be able to withstand that power. How does one build such a switch?
I understand that an IC is not the best solution to this, but I ...
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What kind of matching network this is?
These networks are found in commercially available yagis with folded dipole driven element. I wander what theoretical model is used to design them? Appearently two parallel transmission lines branch ...
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How does the rabbit ears antenna work? [closed]
How do I built a rabbit ears antenna?
I would like to know how a rabbit ears antenna work, like the one shown in the picture below.
From:
https://en.wikipedia.org/wiki/Television_antenna#/media/File:...
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Questions about radio antennas [closed]
I need to know a few things about radio antennas.
As per the theory, the length of any antenna works best if it's length is exactly the same as the wavelength. With that said, if I need to build an ...
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Is there a frequency pair appropriate for a temporary mobile 70cm repeater?
I am thinking about building a portable low power 70cm repeater for field and emergency operations. For example it could be placed up high on a mountain to cover the valley.
Is there an appropriate ...
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Does sporadic E apply to UHF?
ES season is coming up so I want to know if ES applies to UHF. Google says that it applies to 6 meters and 2 meters. What about 70 centimeters? Can I talk further with 8 watts? They say you can DX and ...
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What is this pulsating signal?
When scanning through UHF, I find that there are a few frequencies that made a sound similar to a fast drum (~300 bpm?) Here are a list of the frequencies:
451.200 MHz
454.280 MHz
more coming soon
...
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Converting a 470-694Mhz TV antenna for 433Mhz reception
I'm working on a project which requires me to pick up LoRa signals that will be transmitted from a relatively low gain antenna. I've figured out that a large dipole would be idea for the receiver ...
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RF Coax Termination Question
I am looking to terminate a line with the below characteristics and having a hard time locating an RF coax terminator. Can anyone help?
I have an FPGA HW that is feeding multiple receivers. The input ...
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Entel HT880 Programming Help Needed
I'm a new HAM member in this awesome community, so please take everything with a grain of salt.
First of all, I DO NOT want any CPS programs! Just wanted to make that clear.
Recently, I've received a ...
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why i cant hear my voice when i connect to two Baofeng uv82 to the same repeater frequencies
I have two baofeng uv-82 and I connected both to the same repeater frequency, and once I press the ptt button I can hear the squelch sound on both radios. However, once I talk to one radio, I don't ...
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I am trying to get the 800.00 frequencies on a Baofeng UV-5R
I am trying to use my Baofeng radio as a police scanner and all the frequencies are in the 800.000 frequencies. Example: I am putting 851.1500 into the “scanner”, but the Baofeng radio is not ...
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Optical line of sight over long distances?
Is there a way to use radio to restrict communication to optical line of site at distances greater than 10 miles?
For example, the signal is transmitted directionally from a mountain top fire lookout, ...
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Long Distance antenna feedline for UHF/2.5GHz signal
I'm building a boat towed underwater platform. This underwater platform has a single board computer with a remote wifi antenna connection via a u.fl connector.
I'm experimenting around with a way to ...
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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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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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Is a boom important to a Yagi?
I am trying to make a yagi for a 900M. The tinkering starts causally with some 1.2mm welding wire (cut to size based on K7MEM yagi calculator, direct soldering, no special matching as suggested on ...
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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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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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UHF 70cm unlicensed use
We are farmers with (edit) 25-40w radios mostly old Kenwoods and Motorolas in all of our tractors and vehicles. I'm not exactly sure what frequency we have but the man who programmed them set them up ...
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Baofeng UV-5R: Severe static/interference on UHF frequencies
I have a U5-5R, which I've set up to use (among other things) the analog (NFM) frequencies of the PMR446-band. I've been using it with the stock (136-174/400-520MHz) antenna and a monophone connected ...
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Commercial UHF bands in Sweden
I was investigating satellite (onboard) UHF transmitters. Some of them support commercial and amateur bands. To my understanding, amateur bands span between 430 to 440 MHz and commercial UHF between ...
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Can an antenna be affected if mounted to a bull bar?
When I say 'mounted to a bull bar' I mean the antenna being metal on metal contact to the bull bar without any rubber or fiber glass keeping the materials from touching.
Could this affect the ...
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Looking for specifications for Wilson Electronics WAU 420 amplifier
Hey there helpful people I'm trying to track down some specifications on a Wilson Electronics WAU 420. I have no idea on its exact age but guessing its from the late 90's. It's likely UHF band and ...
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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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Would a transmitter similar to "The Thing" be legal on ham bands in the US?
The Thing was a listening device used by the Soviet Union to eavesdrop on US government officials. It was basically an AM transmitter if I understand correctly, but it required another transmitter on ...
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RF switch for half-duplex sequencing on amateur UHF satellite ground station
I need a 3-port RF switch illustrated below. The idea is to use this switch with a sequencer to enable half-duplex communication on a UHF antenna. The switch has three ports: port A connected to the ...
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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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What kind of soldering iron is best for PL-259 (UHF) connectors?
What do you use to solder connectors onto bulk coax cable?
Soldering the UHF connector to the coax shield on a PL-259 is described as requiring a bit of "experience and skill" in Dave Casler'...
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Correct terminology for a repeating radio transmission
I am using 'active radio tags' in a particle tracking experiment. The tags emit a 433 MHz signal containing a unique ID code at a programmable time interval and I am attempting to locate them by ...
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Turnstile antennas with a "single-point feed": what's the antenna theory behind this, and how do I build/model it?
The conventional turnstile antenna uses a 1/4wl phasing line between the crossed elements, to get the required phase shift. 4nec2 includes an example file, though, of a circularly-polarized Yagi using ...
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Need help in the fabrication of an UHF power amplifier
I recently decided to conceive a 10W class 446MHz amplifier.
I want to be able to amplify a 100mW signal into a 10W, for that i'm going for a two stages amplifier :
SKY65162 to amplify the signal to ...
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Sub GHZ Audio transmission with radiohead library
Can I use sub-ghz (433 Mhz) to transmit audio.I already used radiohead library with RFM96 to transmit small packets of data and built a point to point mesh chat application.
Now i wanted to test FSK ...
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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 ...
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Is power output or something else to blame for my duplexer failing?
A Ham buddy of mine and I were trying to setup a UHF repeater in our area due to a lack of them. We had two Motorola CDMs, one a 1250 and one a 1550, and we purchased a $200 or so reject only duplexer ...
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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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Stacking Two UHF Yagi Antennas
Aloha!
I have two HYS TC-YG05 Yagi antennas that were gifted to me and I would like to stack them side by side ( Collinear), in the vertical orientation for some local weather balloon telemetry data ...
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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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Failing to detect Hydrogen line with 105cm dish
I've seen many examples of roughly 1 metre sized dishes being used w H+ sawbird and an SDR to detect and analyze Hydrogen line signal, and have been trying myself but can't seem to get anything beyond ...
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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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Obtaining input/out impedance from S-parameters for a L network
This L network intend to transform Z1 to 50ohms. The design was made using a smith chart:
The s-parameters plotted (S11 red - S22 green) in the smith chart is done sweeping the frequency from 200MHz ...
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Obtaining S parameters using S11 measurements?
Is it possible to obtain the S-parameters of a circuit with only S11 measurements (S11 measurement with a VNA)?
My gut tells me that it should be possible by connecting open, short and characteristic ...
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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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Can I slant-polarize a bay antenna?
I am trying to work a 700mhz LTE signal with a DB2 uhf bowtie television antenna. I find the cellular signal to be horizontally polarized. Can the bowties simply be twisted 45 degrees in both ...
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440MHz collinear dipole array - suitable coax?
friends!
Finally found my next antenna project..a collinear dipole array for the 70cm US ham band.
The general idea:
(image courtesy https://link.springer.com/referenceworkentry/10.1007%2F978-981-...
user14945
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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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