Questions tagged [vhf]
Very High Frequency is the frequency range 30-300 MHz.
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4 views
STACKING Folded Dipoles
Looking to stack 8 folded dipoles on my 100ft tower.
I can not find any information whatsoever on these.
Bluewave Marathon
BME139FN1H0
138 - 174mhz
Gain 5.5dBd
I have 4 consecutive serial numbered ...
-4
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0answers
38 views
Does a UHF amplifier exist that will boost 5 mW? [closed]
I need to boost my 5 milliwatt HackRF to a jammer level power. Is anything like this available?
Ideally portable and self contained. I expect a 45kg amplifier or something but it has to be powerful ...
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0answers
13 views
How do I alter the low power setting on a QYT KT-8900
There is no difference between the High and Low power settings. Both being around 25 watts.
Is there an internal adjustment or do I have to re-program the radio?
3
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5answers
152 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 ...
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0answers
32 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
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2answers
43 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
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3answers
135 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 ...
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5answers
301 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 ...
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1answer
64 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
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2answers
60 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 ...
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2answers
51 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
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1answer
145 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 ...
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0answers
43 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 ...
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3answers
577 views
Why aren’t emergency services using callsigns?
I’m 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
118 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 ...
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0answers
30 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
751 views
VHF 50 Ω Antenna Over 75 Ω TV Coax
I have a 50 Ω VHF airband antenna which I’m 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
128 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 ...
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1answer
114 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
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3answers
102 views
Weakly directive VHF/UHF antenna
Most resources around the internel discuss common antena types, classifying them between directive (like Yagi) and nondirective (like a simple dipole). Directive antennas are good when you know from ...
1
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2answers
242 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
381 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
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1answer
93 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
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1answer
83 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
913 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
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3answers
411 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
366 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
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2answers
139 views
What wireless communication technologies can travel long distances with a high bandwidth?
I couldn’t 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
3k 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
475 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?
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3answers
320 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 ...
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1answer
402 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
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1answer
111 views
What were the reasons why ATIS identification was introduced?
I am just about to make my inland waterways’ marine VHF radio license in Germany. In Germany, all inland marine VHF radios must be equipped with an ATIS transmitter, which basically sends the stations’...
2
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2answers
588 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
2k 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
465 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
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2answers
356 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....
3
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2answers
390 views
Noticeable difference between trunk and roof mount?
Between trunk-mounting and roof-mounting a 2m/70cm antenna, both as through-hole NMO mounts, is there really that big a difference performance-wise? I mean, I know roof mounting is better, but let's ...
1
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1answer
376 views
2m loop with sense antenna for DF
I would like to construct a 2m Loop with a sense antenna. I have built just a loop antenna with great success that is resonant at 2m finding null's works quite well on local repeater outputs.
I would ...
1
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1answer
90 views
Power handling of a simple VHF ground plane
The ARRL welcome pamphlet contains instructions on building a simple ground plane antenna and specifically comments on its use by handy-talkies. However, I wonder what the actual capability of this ...
2
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1answer
83 views
Help with small dish antenna on 2m/440
I have an oblong dish network antenna that I want to convert to 2m/440 usage.
I have seen the one for the 14 foot dish but I do not have one. Not sure if I should wind a coil and mount it in the ...
0
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2answers
130 views
Any ideas as to what I might be picking up on SDR?
Any ideas as to what I might be picking up on SDR? They make for some strange patterns. Picked them up at the following coordinates: (31.514596, 74.345092) using GQRX, tuned to 217.25 MHz. As for the ...
7
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2answers
1k views
APRS digi path for ISS digipeater?
So when I try to work the ISS digipeater, what should I set the digi path to be?
My setup is a 5 W HT with a 2 m yagi connected to my phone with APRSDroid.
I've tried the past few nights with ...
1
vote
1answer
493 views
What is pinout for headphone FM radio antenna?
My Android phone (as many others) have FM radio receiver on-board. But apparently, it has no internal VHF antenna at all, since there is no signal at all w/o headphones plugged in and sound quality ...
2
votes
1answer
659 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 ...
2
votes
2answers
108 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
141 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
173 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?
3
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2answers
882 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
1k 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 ...
