Questions tagged [vhf]
Very High Frequency is the frequency range 30-300 MHz.
123
questions
2
votes
0answers
44 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 ...
1
vote
2answers
102 views
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 ...
3
votes
2answers
111 views
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 ...
3
votes
3answers
201 views
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 ...
0
votes
1answer
37 views
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 ...
1
vote
1answer
62 views
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, ...
3
votes
2answers
199 views
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 ...
4
votes
2answers
175 views
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 ...
3
votes
3answers
314 views
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. ...
6
votes
4answers
559 views
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, (...
2
votes
1answer
457 views
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 ...
1
vote
1answer
91 views
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-...
2
votes
5answers
692 views
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 ...
1
vote
0answers
130 views
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, ...
2
votes
1answer
114 views
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 ...
0
votes
1answer
90 views
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 - ...
3
votes
5answers
347 views
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 ...
5
votes
2answers
232 views
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 ...
3
votes
2answers
153 views
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?
...
2
votes
3answers
464 views
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 ...
1
vote
5answers
2k views
Can I contact the International Space Station using my Baofeng UV5R?
I saw this article but I can't imagine the power output, (eight watts max) would be enough to be picked up by the ISS at 200 miles above me.
Similarly, I don't know if the preamp on the receiver ...
1
vote
1answer
80 views
Are there any satellite email reflectors?
I'm just getting started using amateur satellites and would like to subscribe to an email reflector, but I can't find one. Is there anything out there?
4
votes
2answers
64 views
2 meter Mode Options
FM seems to be the most popular in the 144 to 148 MHz Amateur Band .Narrow band is used for spectrum conservation . SSB is also used but is more common on the HF bands .Would SSB provide any ...
0
votes
2answers
57 views
Local Relay with static
On our local Relay there are from time to time transmissions, where only static can be heard. Most transmissions via relay can be heard clearly. What could be the cause of this?
4
votes
1answer
167 views
Does a UHF/VHF handheld transceiver kit exist?
I am a licensed ham looking for a UHF/VHF handheld transceiver kit. Unfortunately so far I was only able to find broken links, i.e. Ten-Tec used to produce exactly such a thing but they just don't ...
3
votes
1answer
95 views
How to simulate two antennas in 4nec2
I need to simulate 2 helix antennae placed side by side, and see the resultant radiation pattern. But after adding the second antenna with a separate and when I try to simulate 4nec2, only simulated ...
1
vote
3answers
663 views
Why arenāt emergency services using callsigns?
Iām super new to radio with nobody I know knowing it, so noob alert - plus some extraneous details in case you can comment on any of those.
I got a pair of BaoFeng BF-F8HP radios with recommended ...
3
votes
2answers
334 views
House wiring as an antenna on HF and 2 meters?
The apartment I live in is a 1970s type without access to the outdoors. It does have a balcony. A 2m transceiver is the only radio which will enable me to reach the ham world.
Would be possible to ...
1
vote
0answers
37 views
Unsure how to assemble Shakespeare SSB antenna; not working [closed]
Have 23 foot Shakespeare SSB antenna. Can not connect through the side feed termination band? Antenna not working? What is the band supposed to look like? Is the termination band supposed to be ...
2
votes
3answers
847 views
VHF 50 Ī© Antenna Over 75 Ī© TV Coax
I have a 50 Ī© VHF airband antenna which Iām planning to install in my loft, for use with a RaspberryPi-based RTLSDR scanner/receiver.
I already have a UK-standard UHF/Freeview antenna using standard ...
5
votes
1answer
505 views
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 ...
1
vote
1answer
247 views
Colinear Vhf antenna
Textbook colinear vertical antenna designs show coax cable with alternating braid to centre configuration. Commercial whips seem to utilise a single wire as the radiating element with .66 velocity ...
2
votes
3answers
149 views
Weakly directive VHF/UHF antenna
Most resources around the Internet discuss common antenna types, classifying them between directive (like Yagi) and nondirective (like a simple dipole). Directive antennas are good when you know from ...
2
votes
2answers
517 views
RTL-SDR dongle - what antenna should I use for APRS receive only?
I was following this guide to setup an iGate using an RTL-SDR dongle and a Raspberry Pi. It worked, and I have been able to test it by seeing some APRS packets from a separate transmitter (Arduino+...
5
votes
3answers
423 views
Unlicensed TV broadcasting power limit (Band I)
I'm curious what is the legal limit for unlicensed TV signals being transmitted on the VHF Band I?
This seems ill defined. The part 15 FM rules I am assuming don't apply here. And I don't think it ...
0
votes
1answer
153 views
6 meter mobile antenna grounding
So I've been looking at my different options for 6 meter mobile antennas.
My question mainly pertains to grounding. I've heard hams talk about needing a ground to the frame of the vehicle when using ...
1
vote
1answer
88 views
Mobile VHF/UHF antenna coupling to surrounding objects?
Will a mobile antenna --either mag mount or NMO mount-- couple to surrounding objects such as tall trees, taller trucks, buses, or even people walking by?
If that is the case, would you get slightly ...
3
votes
4answers
2k views
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 ...
3
votes
3answers
975 views
Mounting a J-Pole and Yagi on the same mast
I have two 2-meter antennas, a copper J-Pole and a Hy-Gain VB-25FM. The J-Pole is my all-around antenna, what I use for general 2 meter stuff like connecting to my local repeaters using my main 2-...
3
votes
1answer
621 views
Is a J-pole an appropriate antenna for mounting to a steel handrail?
Last year, a group of us placed a battery-powered 2m digipeater using a J-pole antenna on a mountaintop. We're planning on doing the same this year except we plan to use a surge arrestor from the feed ...
1
vote
2answers
142 views
What wireless communication technologies can travel long distances with a high bandwidth?
I couldnāt find a better place to ask this question, so I have asked it here.
I am looking to transmit and receive internet connectivity wirelessly over a distance of 6 miles (9.7 km) with a minimum ...
2
votes
4answers
7k views
If i connect two antennas to one radio using a t connector will it work?
If I connect two antennas to one radio using a t connector will it work?
If a connect 2 antennas (a mag mount + a dipole?) to the same radio with an adapter will it work normally on 2M band and will ...
2
votes
2answers
830 views
What core material do I need to construct a 1:1 unun for 6M?
I want to build a 1:1 unun for a 6M dipole. Power level 100W. What core material should I use?
1
vote
3answers
424 views
Weird Harmonic Issue on Raspberry PI FM Transmitter
So I talked to my neighbor about my Raspberry PI, harmonics and his emergency radio. He told me to fire it up, as we saw the FCC sticker on it, meaning it is in compliance with Part 15. I started my ...
0
votes
1answer
513 views
Gain in long wire antennas
DARA (you know, Hamvention) TNG is looking for projects. Thursday, I will be proposing building and characterizing a vertically-polarized 1 wavelength on a side reentrant rhombic.
Since in doing the ...
2
votes
1answer
142 views
What were the reasons why ATIS identification was introduced?
I am just about to make my inland waterwaysā marine VHF radio license in Germany. In Germany, all inland marine VHF radios must be equipped with an ATIS transmitter, which basically sends the stationsā...
2
votes
2answers
896 views
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 ...
2
votes
3answers
3k views
Feeding a dual-band UHF and VHF Yagi antenna
I just built a UHF Yagi antenna for my HT, and I was thinking about adding VHF elements. If I do, could I just connect the coax directly to both sets of elements without a diplexer?
3
votes
3answers
603 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?
...
2
votes
2answers
831 views
Is there a DV VHF calling frequency in the UK?
On the band plan for VHF for the UK, I can see 145.500MHz being the FM calling frequency but I cannot find any for DV. Is there one?
In contrast, for UHF, I can see a calling frequency for FM at 433....
