David W Knight
Ottery St Mary,
Devon, UK.

David W Knight

Precision RF bridge
From Transmitter to Antenna:
HF power transmission theory and practice
AC theory, Components and Materials, Inductors and Transformers, Impedance matching, RF bridges.

Fixed vacuum capacitor

Coil resonance experiments
Low-pressure gas ionised by the electric field of a resonating inductor.
see: coil resonance experiments.

Recent additions and corrections:
2015, Sept 19th: The English translation of Paul Drude's 1902 paper 'On the construction of Tesla transformers' has been updated to correct some erroneous unit conversions. If you have previously downloaded this document, please replace your copy with this new version (1.01).
2015, Aug. 10th: Antenna impedance and matching solution calculator [Windows program], by Alexandr Fedaiev.

Gas discharge tubes
Gas Discharge Tubes,
spark gaps & thyratrons

Frequency display
Digital Frequency

Andy Cowley's
Valve Pages

(see also: Introduction)

Nixie tubes
Nixie and other digital indicator tubes.

Demodulators and signal rectifiers
Demodulators and
sigal rectifiers


Kenwood TS430s
Commercial radio equipment. Notes & mods.

Using the SGC 230 'Smartuner' in a balanced antenna configuration.

Racal RA17
Racal RA17:
Adapters, etc.

Astronony &
Radio Astronomy

Web Links -
Radio & Electronics

Last uploaded: 19th Sept. 2015 (3440 files, 356MB)

Neon tube