Amateur Radio Stack Exchange
Amateur Radio Stack Exchange

Questions tagged [mixer]

27 questions
10
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1 answer

How does a switching mixer multiply the two signals?

I understand what a mixer does, and when I see it in a block diagram it's obvious what purpose it serves and how it fits in the overall design of the radio. However, when I look at the schematics and see how it's created, I don't understand how it…
Adam Davis
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7 answers

How does IQ modulation work (intuitively)?

I'm trying to get my head around IQ modulation. What I understand so far is that each of the I and Q branches of the mixer produce two sidebands with the same frequency components, but in the Q branch, these sidebands have opposite phase to each…
John B
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9
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1 answer

How Could Superheterodyne Receiver Ever Work?

I am surprised how the Superheterodyne Receiver still works and is still in use after coming to realise the impact of Image Frequencies on its performance. Basically, I'm curious how engineers make such an architecture work despite the affect made…
Denis
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1 answer

What will the *amplitudes* of mixer products be?

The key fact about mixers, which iirc is even part of the FCC amateur radio exam(s) in the USA, is that they output "the sum and difference" of the input frequencies. And iiuc in practice it's usually assumed that besides those products the mixer…
natevw - AF7TB
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3 answers

What exactly is a "balanced modulator"?

While studying for his U.S. General class license, my son wondered about the "balanced modulator" referred to by a few questions in the FCC pool. Quoting KB6NU's General Class study guide to give a sense of the two questions: Filters are also used…
natevw - AF7TB
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How can quadrature mixing adjust the phase of all frequencies by the same amount? Can it be done in the digital domain?

This came up in some feedback I got when I tried to answer What is IQ in the context of SDRs? and revealed some of my own misunderstanding. Initially, I gave an answer something like (paraphrasing): You could collect I/Q data by taking a second…
natevw - AF7TB
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DIY SA612 + RTL-SDR HF receiver: good on laptop, but huge wideband noise on Raspberry Pi

I recently built a SA612 mixer for HF reception. I used an USB-frequency oscilator to shift the incoming frequency up by 28.8 MHz. I used a random wire antenna outside my balcony and connected it to the center-pin of a car antenna mount, and used a…
比尔盖子
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2 answers

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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MF band mixer - feasible parameters

Trying to build an homebrew receiver for MF band broadcast (Navtext). Usually working on VHF, where all parts are easily found as an IC, but here I'm trying to get back to roots, so I may be missing something. I'm considering a superhet schema and…
gusto2
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How to design a Local Oscillator for a radio receiver?

I have decided to design a Medium Wave radio with discrete parts which won't include much complex ICs or schematics . I am thinking of designing the radio in Heterodyne mode. Which requires an oscillator for resonance and mixture. I think Hartley…
CoderBittu
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SSB Single Conversion Superhet 2nd Mixer IF Termination on Transmit

I have a question about "best practice" in regards to how the 2nd mixer IF port is coupled to (in my case) a 20m double tuned filter on transmit. I'm currently building out the transmit chain for a 20m single band SSB transceiver and I've got as far…
Buck8pe
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How to track down and neutralize this apparent mixer creating noisy emissions around my signal?

When I transmit, it there seems to be something mixing and reflecting my signal. For example, when I transmit on 14.300 MHz, I see signals above my transmitted signal at at 14.500, 14.700, 14.900, etc. and below my signal at 14.100, 13.900, 13.700,…
Rosa
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What advantages does dual-conversion have over single-conversion superheterodyne?

I've seen a variety of radio block diagrams, and some have two mixers inline with the signal. If the signal is already in a frequency range suitable to work with, what does the second conversion/mixer offer that the single-mixer design does not?
Adam Davis
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1 answer

What might this "spreading" interference be?

Any idea what might be causing this signal to appear in the "panadapter" spectrogram of my Omnia SDR around the 40m band? Every twenty seconds, I get a strong "focused" signal that then rapidly spreads out its power — like all the power is…
natevw - AF7TB
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Building an IQ mixer using an in-phase LO splitter

There are many examples of IQ mixers on the internet; all use 90 degree hybrids to split the LO to the mixers with the outputs being combined in-phase. I'm curious, could both mixers be fed an in-phase LO and a 90 degree hybrid used to combine the…
Sam
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