Amateur radio training · work in progress

Bench Test

Interactive pages for the technical part of the amateur radio syllabus. The circuits are solved in the browser as you change them.

Each page turns the circuits from a syllabus group into working instruments. There are controls for the component values. Move one and the page solves the circuit again: the readings update, the waveforms redraw, the working underneath substitutes the new values, and the charge moving round the schematic changes speed to match the current in each branch.

Everything on the page is calculated as you move the control, from a nodal analysis of the circuit. The pages are free, run entirely in the browser, and work offline once loaded.

They are meant to sit alongside a course and the books, for the reader who wants to see a circuit respond before the idea settles.

The pages

Group 2H

Tuned circuits

Resonance, Q, bandwidth, dynamic resistance and the four filter shapes, with the circulating current visible in the tank.

Foundation, Intermediate, Full

Group 2I

Semiconductors

Diodes, Zeners, varicaps, transistor characteristics and biasing, the three configurations, amplifier classes and oscillators.

Intermediate, Full

Group 2F

Sampling

Converters, quantisation, sample rate and aliasing, from what a converter does at Foundation to Nyquist and noise at Full.

Foundation, Intermediate, Full

Each page covers every level that teaches the group. The level buttons at the top switch the whole page, so the same instruments appear with the depth, the equations and the worked answers set for that level.

Still to come

This is a first attempt at three of the technical groups, and the worked answers are still being corrected as they are read back against the question papers. The per level item lists for the remaining groups are ready; the pages are not.
The oscillator page is the weakest. Its figures are right and it draws the right configuration, but the tuned circuit and its feedback tap are described in the text rather than drawn, and the settings available cannot be pushed far enough to stop it oscillating.
Questions at Foundation and Intermediate, once the RSGB publishes those banks. Full level questions are in place with worked answers.
Audio, once the visual side is settled.

Feedback

Any reaction is welcome, and these in particular:

Anything technically wrong, or explained in a way that would mislead someone learning it. That is the most useful of all, and the written explanations are where the mistakes have been so far.
Is the pitch right at each level, and does switching level change enough to be worth having?
Does showing the working with the numbers substituted help, or is the formula on its own enough?
Does the moving charge in the schematic teach anything?

It is free, it will stay free, and it is not commercial in any form.