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1500 questions
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3 answers

What is the point of high gain antenna with respect to the maximum EIRP

OFCOM states that the maximum EIRP within the UK for 2.4 GHz is 100mW. Simply put, what is the point in being able to buy 2.4 GHz high gain antennas which can say do 24dBi, which already puts the output power at 256mW? Is this a case of OFCOM…
R4D4
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Grounding a dipole

How do you properly ground a dipole (RX only for VHF scanning) to protect it against ESD/lightning? In my set up i'm putting a dipole on my roof. I've connected the two dipole elements together with a 100k resistor, and have a balun and amplifier…
Projectile Fish
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Why is coax loss logarithmic?

With DC hookup wire, losses are directly proportional to length. If the resistance of 100m of wire is 10 ohms then the resistance of 200m of wire will be 20 ohms. But we measure coax loss in decibels per given length. For example, this chart lists…
natevw - AF7TB
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What kind of losses do you get from an LC network matching the antenna's impedance?

If you have a transmitter that is perfectly on your frequency but you have an antenna with some impedance what types of losses, and of what magnitude, will you expect from a tuner in between your transmitter and antenna? For example lets say your…
Joshua Katz
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Are directional couplers ever used in duplex repeater systems?

I understand that most single-band repeaters will use a tuned cavity duplexer to isolate the received signal from the transmitted signal, since the frequencies are very close and extremely sharp filtering is needed to separate them. But while the…
natevw - AF7TB
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DAB antenna in roof space

We are setting out our roof-space as an attic, and after decorating, there will be a triangular void under the house ridge, which will be about 36" wide, and 18" high. I can easily fit a standard folded dipole loop antenna for VHF FM, but the DAB…
DaveAt168
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FM squelch SDR algorithm?

What signal characteristics in an SDR receiver signal path should be evaluated or computed to determine whether the audio output should be squelched or not? What sort of computed result should be compared against a scalar squelch "knob" setting? I…
hotpaw2
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Very odd and wide 30m signal. What is it?

A local ham friend copied this strange, wide signal on 30 meters on his Flex 5000. Anybody know what it might be?
Mike Waters
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What are the best APRS SmartBeaconing™ settings for different modes of transit?

There are a variety of websites that give sample SmartBeaconing™ settings – mostly for automobiles, but some for bicycles and pedestrians. I've tried several of these settings and had mixed results. Can anyone share a set of…
Rafael KR7MJ
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ISS APRS Digipeater with Kam XL and ICOM IC-910H

I am trying to use the ISS APRS digipeater which transmits at 437.55MHz. Hardware setup consists of the following ICOM IC-910H. The transceiver has been connected to a Windows PC running a HAM deluxe software package called Satellites. Basically,…
Moses Browne Mwakyanjala
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Linux based SDR spectrum capture via CLI

I need to setup a Linux box to run unattended capture of about 10 MHz - contiguous worth of spectrum (Hardware must support between 500 kHz and 200 MHz) targeting voice (mix of AM and FM voice broadcasts), and another process to selectively…
jbrown
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How large should the call of the remote station be on the QSL card?

I have designed my first QSL card but I'm worried that I may have reserved too little space for the call of the remote station. I'm worried that the buro might have trouble with it. However, I see many QSL cards on this examples page with a fairly…
user885
4
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5 answers

Can a Baofeng UV5R receive airport radio transmissions?

I have tried programming approach frequencies into my baofeng and cannot hear any transmissions. Freq programming was done using a desktop computer connected to the radio to frequency 121.9MHZ. Nothing was heard, just standard background static. …
jason97m
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Signal Source Block of GNU Radio

GNU Radio has a Signal Source Block which considers a set of variables to produce an output, namely sample rate, frequency and amplitude. In signal processing, we define a basic waveform by its frequency, number of samples within the period and its…
Denis
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How do repeaters work? (The technical side)

I'm curious how AM and FM repeaters work. Is the received signal demodulated and then remodulated at the new frequency or do they use some other technique?
vini_i
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