Radio Technical

Noise & Receiver Performance

In this article, I’m going to cover Noise Figure, Noise Factor, Noise Power, Receiver Bandwidth, and how they can affect overall radio receiver performance. Contrary to popular belief, these metrics have nothing to do with man-made interference. Noise Power Noise Power is the integral of the noise power spectral density over a given bandwidth, usually […]

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Charger Radiated Emissions

I usually have a respectable HF noise floor at home, for which I count myself lucky in today’s sea of cheaply made switching power supplies. However, we were expecting some severe winter weather a couple of weeks ago (it never materialized, but that’s beside the point) and I noticed that my noise floor had gone […]

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UR6QW Processor with Dynamic Microphones

While this post is written with the UR6QW processor in mind, it contains information which is widely applicable. There is some concern about connecting dynamic microphones to devices which commonly use electret condenser microphones. I believe this requires some clarification. Electret condenser microphones generally require about 3 to 5 volts DC to supply an internal […]

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What is characteristic impedance?

The RF world is full of esoteric terminology, and not least of these is characteristic impedance, or Z0. Most coaxial cables have a characteristic impedance of 50 or 75 ohms. If you want to know why 50 ohms was arrived at as a sort of standard for radio applications, you can read this post. In […]

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QUCS for Filter Design

Introduction QUCS, or Quite Universal Circuit Simulator, is a freeware utility that allows you to draw circuit schematics, and perform AC & DC simulation, noise simulation (for S-parameters, and AC simulations), S-parameter simulation, and a whole lot more upon them. I first tried QUCS about a ten years ago, and for whatever reason (lack of […]

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Antenna Tuners, Impedance Matching, and SWR

Antenna tuners seem to be some of the most misunderstood devices in all of amateur radio. In this article, I’ll try to explain what is happening when you use an antenna tuner. I’ll try not to get too much into mathematics, and I’ll also try to squash a few myths. I really don’t like the […]

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Switch-Mode vs Linear Supplies

Amateur radio transceivers demand power supplies which have a large current capacity. The average 100 watt radio transceiver requires over 20 Amps when in transmit mode. Overview A linear power supply uses a large heavy transformer to step down the input high voltage AC to a level close to the desired output. From there, the […]

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IC-7300 Average SSB power modification

If you Google the title of this post, I’m sure you’ll come across some results which detail a very simple modification you can make to your IC-7300 which some believe increases the RF output power. This is vague and misleading. The PEP (Peak Envelope Power) of the IC-7300 is rated at 100 watts. This would […]

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LMR-400 for Ham Radio?

I see lots and lots of posts from people extolling the virtues of using LMR-400 coaxial cable in their ham radio setups. LMR (Land Mobile Radio) cable was developed by Times Microwave Systems as a high quality coaxial cable which can be used with excellent loss properties at frequencies greater than 1 GHz. If your […]

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Coaxial Cable Length Does Not Change Antenna SWR

I’ve heard this for decades, and I first heard it when I got into CB radio when I was a kid. You’ve gotta to cut your coax to the right length if you want low SWR’s More accurately, if you are driving a mismatched load (e.g: a poorly tuned antenna) it depends where along the […]

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