Questions tagged [vhf]
Very High Frequency is the frequency range 30-300 MHz.
99
questions
0
votes
2answers
26 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
115 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
0answers
34 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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vote
3answers
545 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
95 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
24 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
723 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
86 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
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1answer
90 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
95 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
vote
2answers
153 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
368 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
77 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
72 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
770 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
292 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
284 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
135 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
2k 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
396 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
265 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
356 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
94 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
votes
2answers
503 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
424 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
278 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
votes
2answers
341 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
vote
1answer
299 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
vote
1answer
83 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
votes
1answer
77 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
votes
2answers
129 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
votes
2answers
927 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
397 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
603 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
106 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 ...
1
vote
2answers
132 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
161 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
votes
2answers
687 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 ...
1
vote
3answers
341 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 ...
9
votes
4answers
662 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 ...
12
votes
3answers
6k 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,...
7
votes
2answers
986 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 ...
6
votes
7answers
4k 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 ...
2
votes
1answer
192 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....
0
votes
2answers
66 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 ...
1
vote
1answer
143 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 ...
0
votes
1answer
124 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 ...
1
vote
1answer
63 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 ...
