Understanding dB, aka go easy on your HF amplifier!
I was listening to a couple of guys on the 20m band today and they were discussing amplifiers… “Yeah, this amplifier will do 1500W. The last one I had would only do 1000W so...
Category: Radio Technical
Icom IC-7300 & IC-7610 “Built-In” Tuning Pulser
Overview A tuning pulser is a device which generates a series of short-duty cycle tone bursts which are applied to the audio input of a transmitter. Instead of tuning up a tube linear amplifier...
Antenna Materials & Efficiency
You can not make a very good antenna using insulators like PVC tubing, drinking straws, or nylon rope. I think we can all agree on that. Why? Materials like plastic are electrical insulators, and...
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...
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...
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....
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...
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...
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...
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...