Amateur Radio Stack Exchange
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1500 questions
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Dipole Center Spacing

I have a question about dipole construction. I am working with a turnstile, but building dipoles to validate my system with linearly polarized transmission before moving on to circular. My design has a turnstile deploying from a cubesat, but the…
Kontakt
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Receiving commercial / public-safety on a general-coverage HAM transceiver

I have an ICOM-7100 that I've installed in my mobile as my primary (nay, only) HAM transceiver; and I'm trying to avoid wasting a ton of space in my vehicle (not to mention money) for a proper scanner, or for a CB¹, to achieve fuller coverage of the…
ELLIOTTCABLE
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Measurement/calibration error after OSL calibration on VNA

Purchased a HP 8711A some time ago to learn how to make better measurements. I've tried doing an OSL calibration with a 75ohms Agilent cal kit. When reconnecting the short after succesful calibration, I would expect to have a return loss of 0dB…
Dieter Vansteenwegen
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4NEC2 - Radiat-eff. vs. Radiat-power

In the output from 4NEC2 the input power is 100 W. On the left, in blue text, is Radiat-eff. which equals 15.41%. On the right is Radiat-power which equals 94.88 W. I would expect either the first to be 94.88% or the second to be 15.41 W. Why the…
user34299
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In the context of the mixer in my radio, what does balanced and unbalanced mean?

I'm trying to understand how the mixer in a radio actually works, at a physics level. When looking at this article and studying the first schematic I realized I really don't understand what balanced and unbalanced means in that context. Could you…
flickerfly
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Signal generator giving DC output?

My signal generator is giving DC at its RF OUT port. At 500 MHz & 1GHz it's giving nearly 1.5V DC when I measure the voltage between the centre pin & outer conductor with a multimeter. I don't know whether this is the right way to measure or whether…
Geoabs
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Can antennas have reverse harmonics

I know antennas can have 1/4 wavelength, 1/8th etc. but if you are operating from UHF bands, can the antenna be lets say twice as long?
Skyler 440
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Using a loop antenna on a harmonic of the intended antenna frequency

I bought a MFJ 1786 Magnetic Loop Antenna, which is made for 10 thru 30 MHz. It is not meant for use on 40 meters. The antenna has its own built in tuner. I have a Yaesu FT-890AT with built in antenna tuner. So my question is: could I tune the loop…
jim
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Air gapped digital communications mode on VHF?

According to this question MCW (modulated continuous wave) is allowed on large portions of the VHF bands in the U.S. Is using MCW suitable for passing small amounts of digital data between 2 PCs or mobile phones using just air-gapped audio…
hotpaw2
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How can I counter DC-DC inverter noise / ground noise in an electric-vehicle mobile setup?

So, I'm relatively new to all this; and I've gotten an ICOM IC-7100 on sale, which looks like an excellent transceiver … unfortunately, this very specific line shows up in the manual: The transceiver may not receive well on some frequencies when…
ELLIOTTCABLE
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Mounting my antenna

I just bought a CB and mounted it in my truck. I ran my antenna to the back and was going to stick it to my tool box but it turns out to be aluminum, so I'm thinking of bolting a metal plate to the top so the magnet will stick. Should I attach a…
B Wingfield
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How big is a decibel?

Say I've calculated that my feedline losses are 3dB, or I'm considering an antenna with 10dB gain, or trying to decide between a transmitter with 10dBm output power versus 16dBm (6dB difference). I understand a decibel is a degree of change in…
Phil Frost - W8II
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Distance between antenna and radio

I live in a small cottage with an unlevelled terrain. My house was built in the lower part of it (left-side), and in the other half of it there is a hill. On top of the hill there's a fairly good plateau where I would like to have my antennas…
Former User of Mine
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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 like, and I'd like to keep the receiver electronics…
mindcrime
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Can I use old TV FM card as SDR?

I tried searching a lot before, but couldn't find anything about it; I have an old TV/FM card from an old computer, I wish to know if it can be used as an Software Defined Radio, and if yes, how? The one I have is the same as this…
Miguel Vieira
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