Questions tagged [vhf]
Very High Frequency is the frequency range 30-300 MHz.
94
questions
1
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0answers
22 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
701 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 ...
4
votes
1answer
73 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
76 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
90 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
109 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
366 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
68 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
69 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
692 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
239 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
249 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
133 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
345 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
240 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
325 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
89 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
462 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
1k 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
395 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
245 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
288 views
Noticable 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
240 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
80 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
73 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
128 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 ...
6
votes
2answers
870 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
363 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
575 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
105 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
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2answers
127 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 ...
0
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2answers
156 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
596 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, ...
0
votes
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
326 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
624 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 ...
11
votes
3answers
5k 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
975 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
185 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
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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
141 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
120 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 ...
3
votes
1answer
167 views
What is the best way to get propagation VHF map for FM repeater?
Is there a way to get a professional propagation map for my VHF 50 watt repeater?
3
votes
1answer
3k views
Programming VHF To CB
New to this particular site on StackExchange and new to amateur radio period so bear with me:
I'm looking into buying a VHF radio for work related purposes. More specifically the Icom IC-2300H.
I've ...
5
votes
3answers
2k views
Good FM receiver single-chip IC for simple VHF receiver?
Is there an IC out there that implements all, or most all, of a simple FM receiver in the VHF range? I'm interested in doing some experiments with using DTMF over the air for tele-commands and the ...
7
votes
3answers
2k views
Antenna for a cramped attic
Brand new Ham. I bought a cheapo UV5 right before I got my call sign. I want to set up a decent 2m/70cm station for starters and I realize that a better radio is important but wanted to knock out the ...
6
votes
6answers
11k views
Is packet radio possible on Baofeng UV-5R and similar HTs?
I am curious to know if it is possible to do packet radio on VHF/UHF using the UV-5R... I have seen some invasive hardware hacks, but without modifying the radio itself (firmware, hardware) it's my ...
