All Questions

Filter by
Sorted by
Tagged with
1
vote
0answers
68 views

Simple Gnuradio TX/RX loopback example/tutorial

I'm looking for some sort of simple and a beginner level instructions on how to build TX/RX loopback flowgraph using GnuRadio software and B200 USRP with an attenuator FW -10 + 10dB. Kindly, help me ...
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
722 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 ...
3
votes
0answers
81 views

GnuRadio RF transmission, legal and safety issues

I'm trying to run some transmit/receive RF examples that I found online using GNU Radio with USRP B200. I read and heard about some cautions in terms of transmitted frequencies here in the USA which ...
3
votes
1answer
85 views

Fan dipole with loading coil(s)?

There seem to be plenty of construction articles on center-fed wire fan dipoles with pairs of arms of different lengths, each pair dimensioned for a different band (e.g. half-wave 80M+40M+20M). Would ...
2
votes
2answers
752 views

What is this burst transmission sequence across the entire band?

Fairly regularly on the 40m band I hear a quick blip of a tone, and when I look at the waterfall I see these brief transmissions all across the band that look like little dots. What is causing that?
2
votes
1answer
39 views

Using EchoLink with Satellite delivered Internet

I am new to Echolink and I have Hughes Net Satellite delivered Internet service. Can I use Echolink with my Satellite service since there is a longer delay involved. Thanks in advance for your ...
1
vote
3answers
65 views

2m 5-element yagi with staggered driven elements

I have seen sketches of 3-element 2m yagi antennas in which the driven dipole elements are staggered i.e., one element is positioned slightly in front of the other along the length of the (plastic) ...
3
votes
1answer
216 views

How do amateur satellites stay consistently in the amateur-sat bands acoss the globe?

I understand that my local laws may differ but amateur radio satellites, by their very nature, orbit the earth going over several legal jurisdictions. Are satellite bands the same internationally? If ...
1
vote
1answer
63 views

Radio antenna for my FM receiver / Android FM

I want to make a radio antenna at home which will be able to receive all FM frequencies for my FM radio or Android FM. How do I make it? Frequency it can catch : 88 - 108 MHz Thanks.
1
vote
0answers
22 views

FLDigi Crashes When Trying to Load RigCAT Description File

I am trying to setup FLDigi with my ICOM-7300 via the USB connection so I can start using digital modes. Everytime I try to follow the instructions here, it doesn't work. Specifically, everytime I try ...
1
vote
1answer
24 views

Power output of KT8900

Any ideas on adjusting the low power output of the KT8900. The output tranny has a max rating of 12V and specs are centred on 7.5 volts. Yet they try to run it at 13.8V?? I want to reduce the output ...
2
votes
2answers
67 views

Orange Goop Leaking from Power Supply

I have a Baofeng UV-82 with the charging cradle and switching power supply (wall wart). Tonight, I noticed a slick spot on the floor next to the couch, and saw some orange goo on a paper I had picked ...
5
votes
1answer
81 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 ...
9
votes
5answers
1k views

Will electrically joined dipoles of different lengths, at right angles, behave as a multiband antenna?

I haven't seen this done, (which, after more than a century of amateur and professional radio development, is probably a bad sign), but I had an idea the other day for simplifying the setup and feed ...
2
votes
0answers
48 views

HackRF One and IoT overloaded?

I'm transmitting Z-Wave frames using HackRF One in loop, one frame every second. Has anyone clue why are some frames not transmitted? You can see several too long gaps between frames on Waterfall (...
4
votes
1answer
82 views

Dipole symmetry?

In ideal free space, both arms of a tuned wire dipole will be of identical length. However, the real world is not perfectly symmetric free space. The support heights, ground levels, ground ...
3
votes
2answers
126 views

Can I take and use Baofeng UV-82 in Norway?

Planning to go for a camping trip. According to this document (in Norwegian but easy to understand), I can use a radio running PMR446 and KDR 444 freqs. Baofeng can do this. The question is: is the ...
1
vote
1answer
74 views

Simple antenna for LoRa 433 MHz module

I have some LoRa SX1278 433 MHz modules: However, I don't have an antenna. My question is: what would be a good antenna option for longest range? I don't really care that much about transfer speed, ...
1
vote
0answers
25 views

Baofeng 888s side key didn't work and solved [closed]

Thanks. Solved. Baofeng 888s, programmed with chirp, worked great. I hit the device with CHIRP many times, Everything was ok., but moni button after a month, didn't work. First I thought that the ...
5
votes
2answers
57 views

Propagation effects of noctilucent clouds

I know auroras are a propagation mode, but I was wondering with the recent outburst of noctilucent clouds (as reported on www.space.com) brings with it any interesting propagation modes, either on HF ...
2
votes
1answer
60 views

How do I interpret the FCC ground conductivity files

The FCC has .seq files that show ground conductivity which it makes available for download. Unfortunately, there doesn't appear to be any documentation that comes with the files, or even headers. I ...
5
votes
4answers
2k views

How does a receiver know the exact frequency in the channel to “listen to”?

I am reading about how radio communication works and I have an unanswered question. We have wideband channels with 25kHz of radio spectrum. The transmitter modulates a signal and sends it. The ...
1
vote
1answer
38 views

Clarification: What are Fixed and Mobile services intended for in frequency allocation documentation?

Question Does a band allocation to "Amateur", "Fixed", and "Mobile" mean that it's for amateur radio use by fixed and mobile services, or does it mean that all these services are separate but equal? ...
1
vote
0answers
30 views

Baofeng 888s sidekey (moni) don't work

Baofeng 888s, programed with chirp, worked good but maybe at change channels during pushing moni button or something else (I don't know), don't work. I tried to change side key options by programming, ...
2
votes
1answer
60 views

Transferring old callsign to a club?

A new vanity callsign will be granted to me (currently in pending level 2 stage). Can I transfer my current soon to be cancelled callsign (vanity) to a club which I am trustee without waiting the ...
1
vote
1answer
59 views

Combining/splitting three different RF signals

Not being so fluent in RF, I decided to ask here if my current approach seems doable or how one would try to achieve something like this: I'm doing research and deciding on an approach for my proto-...
9
votes
4answers
140 views

Why are there so many coaxial cable impedances?

Why do we have 50, 75, 62 and 92 Ω coaxial cable, to name a few? Why not just one standardised cable? Is there some technical reason or did Mr. Coax and Mr. Cable have a disagreement, like Mr. Tesla ...
5
votes
3answers
98 views

Is Field Day a contest?

Is the ARRL Field Day a contest, or is it not a contest? Kindly explain the reasoning behind your answer. A non-ham could not tell the difference.
1
vote
3answers
116 views

Using 75 Ω instead of 50 Ω coax feed

Can I replace my old 50 Ω coax with RG6? It's cheaper and less loss at VHF/UHF. I would match by L/2 multiples of coax to repeat input and output impedance or L/C matching networks at each end. Is ...
5
votes
1answer
449 views

What does “THREE ALPHA in Virginia” mean?

I'm listening to the 40m band during Field Day and I keep hearing things like "You are THREE ALPHA in Virginia," or "do you hold me ONE ALPHA in Eastern Pennsylvania?", or "you are TWO ALPHA Maine." ...
6
votes
1answer
104 views

How do Field Day participants protect from lightning?

I'm planning to attend Field Day this weekend, and the forecast calls for thunderstorms. I can picture a serious issue with a bunch of temporary antennas set up in an open area when a thunderstorm ...
3
votes
3answers
122 views

Applications for 100 GHz band?

I was reading this paper and I found it very interesting and the following question came up, What are the main applications (what is used for) 100 GHz band? I couldn't find any reference on what is ...
1
vote
1answer
87 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
1answer
108 views

How does one know how a signal has been modulated

I am trying to intercept signals from a drone remote controller and decode them. Before I can do this I need to demodulate the signals. All I have is radio data from the transmitter's operating ...
1
vote
2answers
84 views

How to plot transmitter coverage area?

As an Extra class licensee, I should probably know this... I am working on a web application for repeater owners. I would like to include an estimated coverage area, provided they have entered all of ...
2
votes
3answers
91 views

FD Battery Stations… How Do You Log?

I'm part of a small team that runs 3AB with a few Kx3 radios. We've been struggling a bit with logging. First year was all paper and that was messy. Next couple of years one of the guys put together ...
2
votes
3answers
97 views

Add capacitor to unload antenna?

So add inductor coil(loading coil) is to cancel out capacitive reactance to make the antenna electrically longer. But what if a capacitor is placed on the antenna, to make the antenna electrically ...
2
votes
1answer
46 views

Dielectric Constant of Insulation/RF Permeability

I recently purchased a 500-foot roll of military surplus 14 AWG stranded copper wire at a hamfest for next to nothing . It is Prestolite M13486/1-6 (spec sheet). It has very thick chlorinated ...
1
vote
1answer
36 views

Are stainless steel studs acceptable as a feedpoint connector for an aluminum loop antenna?

Similar to Will stainless steel bolts work with my copper antenna? however my concern here is with electrical properties. With copper antennas I never gave it much thought... just solder the wire. I ...
3
votes
1answer
67 views

Why is GNU Radio “stuttering” with this flow graph?

I have a GNU Radio Companion flow graph, where I have the following connections: 440Hz cosine wave throttle block audio sink All of the above blocks use the same sample rate (48KHz). When I ...
5
votes
3answers
146 views

Feeding a folded dipole

Can I feed a folded dipole constructed of hollow tubing by threading coax through the element to create both an impedance transformation and balun? I have fed coax through the tubing of the dipole ...
3
votes
2answers
85 views

Grounding a chimney mounted antenna

I'm installing a new antenna mast to hold one or more antennas. The new mast will be strapped on to a chimney near the center of my house. Coax will run down the mast, across the roof, down the side, ...
0
votes
1answer
95 views

How hard to send files [duplicate]

How hard and expensive would it be to send a file from my house in London to a coastal area in Spain? It would most likely be software I want, so it must transfer perfectly, however if it is feasible ...
3
votes
1answer
67 views

What are the parameters and necessary features of a Gunn diode oscillator cavity?

There are a ton of old USSR Gunn diodes available on ebay and I'm looking for a cavity that can make use of them. I am willing to machine one myself if necessary, but I'm unable to find any decent ...
2
votes
2answers
136 views

Restricted line-of-sight communication

Why do line of sight communication links have a restricted range for a given tower height? Is it only because of the Earth's Curvature?
6
votes
2answers
389 views

Multiband vertical antenna not working as expected

I built a vertical out of a 5M aluminium pipe. It tunes fine (and wide!) on 20M. I decided to add a loading coil to operate it on 40M, and it also worked fine, albeit not so wide. While I was at it, I ...
10
votes
1answer
137 views

Dominant speeds of Morse Communications

5 wpm is easy to learn and better than nothing in emergency. Speed Morse Coding is fine for "sport competition" I am trying to find out which is the typical speed for what I call "conversation" and ...
3
votes
1answer
106 views

What are the effects of a ground plane under a horizontal dipole?

What are the effects on signal propagation if this ground plane is just a metal object and what are the effects if the ground plane is actually grounded? I am asking this question because someone ...
1
vote
0answers
67 views

Uplink-limited vs. Downlink-limited

What is the definition of these terms? Would a system with signal to noise ratios of uplink 100dBHz and downlink 80dBHz be downlink-limited?

15 30 50 per page