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2
votes
1answer
75 views

What sort of antenna would use a bicone or lozenge-like arrangement of vertical wires?

In another QA here, there's a picture of an antenna I identified as a "discone": What are these antennas used for? One commenter noticed that antenna was actually a "Discone, but no disc, just the ...
2
votes
3answers
247 views

Is there a way to split a frequency into channels?

Is there a way where I can take a single frequency and subdivide it into channels so theoretically I can transmit multiple voice channels on the other?
2
votes
5answers
521 views

Significance of 1/4 wavelength with respect to antennas

I am a new to the radio design field. My question is, 'What is so significant about 1/4 wavelength with respect to antennas.' From the information I have gathered from various sources, it is my ...
2
votes
2answers
129 views

How far from a cable entry point can the lighting suppressor be installed

I'm installing a transceiver in an office on the ground floor of a warehouse. The antenna will be 45 feet above the office on the roof of the warehouse. The ceiling of the office is a drop ceiling, ...
2
votes
2answers
2k views

GNU Radio does not run flow graph

I am sorry but yet again a question about GNU Radio. (I just started following some tutorials a couple of months ago and am learning about it. I am unfortunately not that proficient in it yet, but I ...
2
votes
2answers
192 views

Double Cross antenna: what's wrong with my model?

Important note: After consulting another source, I learned that the article calls for the first pair of opposing dipoles to be fed in phase, with the second pair fed in quadrature to the first pair (...
2
votes
2answers
233 views

Why do you have to be 18 to be a Volunteer Examiner in the US?

I am a 15 year old ham, and just got my Extra class. I was really bummed when I figured out I needed to be 18 to be a Volunteer Examiner administer. Why do they make that rule?
2
votes
2answers
482 views

Adapting an antenna tuner for use with a panel meter instead of an LED

I'm building NorCal's / W6JJZ's BLT tuner (pdf) for use on 40m/20m with a 5W transmitter. I would like to remove the LED and use a small panel meter instead. I don't have a 1N34A at hand, but I do ...
2
votes
1answer
99 views

tuning trouble - 1/4 wave 8 elevated ground radials 10 meter

It is resonate for 22 Mhz haven't had any luck tuning it for 30 Mhz it is an excellent antenna I feel at the Z is 0 for 22 Mhz I have given up and think I will just buy a Imax 2000 w/ radials?? "10 ...
2
votes
4answers
722 views

What is the maximum and minimum of antenna gap of dipole antenna?

Consider the picture below is design of half wave length (λ) dipole antenna. I read some explanations saying that it is the best design to get the optimum transmit power. Half wave length (λ) is from ...
2
votes
2answers
851 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
1answer
248 views

Two devices + one antenna

What I have: GSM 900 repeater 900 - 2400 MHz MIMO antenna 2xSMA MIMO 4G Router works with 1800 MHz LTE Is it a good idea to connect GSM repeater via SMA splitter to one of the antenna cables? Will ...
2
votes
1answer
98 views

How to scan while avoiding digital/noise frequencies?

Is there an established way of scanning frequencies, while avoiding listening to digital signals or static? For example, is there a scanner on the market which will allow you to blacklist a specific ...
2
votes
2answers
545 views

Loop Antenna - configuration?

Due to space limitations, I'm looking at loop antenna designs. I'm starting with receive only, but hope to eventually transmit. I've seen magnetic loops (single turn with a coupled loop) and I'm ...
2
votes
2answers
5k views

Converting WPM to CPM

I'm using an Anroid app for learning CW. In Germany, it's common to define the speed in CPM ("characters per minute", or German BPM for "Buchstaben pro Minute). However, the Morse trainer I use ...
2
votes
1answer
708 views

How does a gamma match on a dipole work as a balun?

I have a resonant half wave dipole which is one continuous length and not separated in the middle, fed using a gamma match, and with the braid of the coax joined to the exact electrical center of the ...
2
votes
1answer
184 views

What type of digital mode is this?

Currently trying to figure out what type of digital mode I'm listening to. I've purchased a Vaisala Radiosonde RS-92AM. It's a meteorological device usually attached to below a weather balloon. I've ...
2
votes
2answers
634 views

antenna circuit to hear or show radio direction

Is it possible to create a circuit to hear (through earphones) or show (with an LED) the direction of a radio source? What does a really simple circuit look like and how does it work? How does the ...
2
votes
2answers
2k views

Receiving without configuring CTCSS

I'm interested in listening to the local EMS/Fire transmissions around here and was wondering if I have to configure the CTCSS/PL tones on the radio in order to hear those transmissions. I understand ...
2
votes
1answer
457 views

Will these wires affect antenna performance negitavely?

We moved into a new house, and I noticed these wires sticking up for some sort of tent thing for shade. •I tested the wires to the 3rd prong in the outlet, and it showed a DC dead short to ground. •...
2
votes
2answers
385 views

Which Digital voice mode?

I am looking to get a handheld radio that does digital. Requirements •The most open-source, tweak-able system that I can mess around with. •The lower end price wise •A system that actually gets ...
2
votes
1answer
65 views

What circuit to use to multiply 434 MHz by two?

I wanted to make an experimental simple 1296 MHz transmitter to have fun with my sdr dongle. But after hours of googling I realised that there is no such thing as "simple 1296 MHz transmitter". Even ...
2
votes
2answers
107 views

Transmission speed of modern digi-modes

What are the bit per second ratings and signal-to-noise-ratio ratings of various modern, popular, good performance and well supported digi-modes for HF low power (0.1 watt) long distance (500 to ...
2
votes
1answer
740 views

Adding a panadapter via SDR

I've become very accustomed to the waterfall display on my SDR, especially for digital modes over HF. I'm thinking about tying into the IF on my IC-718 and connecting to an SDR to add a waterfall to ...
2
votes
2answers
396 views

Replace directional antenna by fixed antenna

Given the following specs of a directional antenna: ...
2
votes
1answer
346 views

Can HDSDR perform the work of Direwolf?

I have a setup in which Direwolf is used in conjunction with a Baofeng radio to basically send data (AFSK). My app connects to the TCP server provided by Direwolf, send him some data which then is ...
2
votes
1answer
448 views

Is there an 8-Watt “Upgraded” Baofeng UV-82?

I recently purchased a Baofeng UV-82 from a seller that advertised it as an "...Upgrade 8W". There are a fair number of these on Ali Express. Assuming it was a UV-82HP and the seller got the listing ...
2
votes
2answers
424 views

How does keying a CW transmitter work?

In my handbook it talks about keying the transmitter to produce the dots and dashes. Does this mean that the operator is turning the transmitter on and off, or does this mean that the key is turning ...
2
votes
3answers
164 views

Is double amplitude modulation useful?

If i amplitude modulate an AM carrier with an audio signal, can i then feed that resultant AM waveform into another modulator and amplitude modulate the AM signal to give a signal which is amplitude ...
2
votes
1answer
88 views

Can I filter after modulation when using a square wave oscillator? [closed]

Most designs appear to filter most of the harmonics out of the oscillator before modulation, then apply additional filtering as needed for the specific modulation they are using after modulation. ...
2
votes
2answers
2k views

Field Strength calculations with known antennas

I can receive a calibrated decibel milliwatt signal level from the output of any antenna at a given frequency. With a given antenna gain (dbi) in the direction I want to receive the signal (...
2
votes
2answers
541 views

Yaesu G-5400B rotator controller problem

I'm currently facing a little problem with our Yaesu controller. I have done all the calibration and the controller appears to be working fine. Unfortunately, it does so for short duration (a couple ...
2
votes
1answer
160 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 ...
2
votes
4answers
2k views

Voltage vs. Current Balun for Dipole

I'm a new radio amateur setting up a half-wave 10-meter inverted vee antenna fed by 50 ohm coax. I understand that the inverted vee lowers the normal 72 ohm dipole closer to 50 ohms, so I only need to ...
2
votes
1answer
646 views

Horizontal dipole radiation gaps

Consider the radiation pattern of a horizontal dipole mounted at a height of 1.75λ. Is it possible for a receiving station's antenna to be mounted at a certain height such that the radiation of the ...
1
vote
1answer
116 views

Double Cross Dipole antenna for 437 MHz don't tune

I'm building a Double Cross Dipole antenna for 437 MHz to be used with a SDR receiver for CW cubesat. The idea is to follow this "classic" paper from Gerald Martes, KD6JDJ. I tuned every single dipole ...
1
vote
2answers
2k views

How to best connect an FM transmitting GPIO pin to an antenna?

I'm trying to use a RaspberryPi3 as a FM transmitter, using pifm and/or PiFmRds to send audio in 88-108 MHz band. The RPi can then use the GPIO-4 pin to transmit between ...
1
vote
3answers
171 views

Long range HF polarization

Is it possible to polarize HF signal (20-30m) at long range (thousands of km)? It was commented in my over questions that polarization is not feasible at long range. However in this article is ...
1
vote
2answers
3k views

Wiring a CW paddle

What kind of cable would be suitable for wiring an MFJ-564B Iambic CW Paddle to an Icom IC-718? I have heard that you can just use a length of old electric guitar cord but I was not sure what to do.
1
vote
2answers
1k views

MIC microphone ground vs common (PTT, chassis etc) ground

How do we reconcile the ground connection between audio eqp (TNCs, soundcards etc) and transceiver? Most of the audio eqp for digimodes has only one ground. I've seen that the common practice is to ...
1
vote
3answers
3k views

Shortwave / CB / HAM?

Are all of these the same? Shortwave, CB, and HAM If they are not the same, which one is better? Which one can be easily hidden (doesn't HAM need a big antenna?) for broadcasting?
1
vote
3answers
97 views

Why is outer coax usually grounded?

I'm building a simple ground plane antenna for VHF, and I'm doing some research on grounding in case I want to permanently install it. I keep hearing that the ground rod is connected to the outer coax ...
1
vote
1answer
69 views

Sunspot numbers? forecast? broadcast on CW/HF

I have vague memories from the early 1990:s of some sort of service that broadcast something related to sunspot numbers, in CW, probably shortwave. I think the world "BOULDER" was in there ...
1
vote
1answer
41 views

Bidirectional motor control using MFJ-4116 with RCS-4

I have the RCS-4 with two MFJ-4116. Prior to installing my motorized HF antenna system topside, I bench-tested the core of the assembly in my shack. The MFJ-4116 near my transceiver was injected with ...
1
vote
2answers
2k views

How to make a loop antenna for HF?

While researching this answer, I came across information that indicates that a many good Low Frequency/ Very Low Frequency antennas are loops, with high directionality and good overall characteristics....
1
vote
2answers
83 views

Vertical antenna

I'm installing a vertical antenna in back yard. About 20 feet in height and using 1 counterpoise wire 16 feet for 20 meters. Does installing two or more counterpoise wires help?
1
vote
2answers
686 views

GMRS not transmitting within a half mile

I recently got my GMRS license from the FCC, and I wanted to try out a couple radios for hiking and emergency communication. I have two tenway UV-5R pro radios (these do have an FCC ID) that are set ...
1
vote
1answer
65 views

Effect of small amount of metal on twin-lead

I have a G5RV Jr. antenna on a fiberglass mast at 10m height. The only metal on the mast is a 1/8" thick steel guy ring with stainless steel snap links, plus a few small metal screws. Hanging freely,...
1
vote
3answers
2k views

Can I build a mini passive repeater to improve my WIFI reception at home?

The problem There's a concrete wall between my computer and my router (Linksys E900) which affects my WIFI reception pretty harshly, computer receives signal is at -65 dBm, at this rate i get around ...
1
vote
2answers
654 views

Exactly why do some SWR meters give a changing reading depending on the length of coax used to connect to an antenna?

Following is my understanding of some theory and the questions are at the end. Is this right ? ... A standing wave is an AC waveform oscillating at a particular frequency which has a varying ...

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