PA3FWM's Technical Notes

Pieter-Tjerk de Boer, PA3FWM pa3fwm@amsat.org

Since 2009, I semi-regularly write articles for the Dutch amateur radio magazine Electron, under the title "Technische Notities van PA3FWM". Some of these articles focus on a single topic, others address several smaller topics. The topics can be anything technical and amateur-radio related, but tend to emphasize SDR and radio fundamentals. The articles are originally written in Dutch, but since they may be of interest to a broader audience, I try to translate them and publish them here in English.

So far, the following installments are available here:

July 2012 about:
March 2013, about chirp reception and interpretation
(including some fundamentals of shortwave propagation)
January 2014, about fundamentals of the MiniWhip antenna
(including discussion of directivity of antennas, and a demonstration setup of electric potential measurements)
May 2014 about:
- Exponentially switchable coil, about my design for an inductor that can be varied over a large range, as an alternative to a roller inductor in an antenna tuner.
- Capacitance of antenna elements, about the capacitance of metal rods and plates that are often used as antenna elements in active antennas, such as the MiniWhip.
- High-frequency currents in a printed circuit board; this part was basically a short summary of, and reference to, this very read-worthy document: Mark Fortunato, Successful PCB grounding with mixed-signal chips, http://pdfserv.maximintegrated.com/en/an/TUT5450.pdf, and therefore not translated and reproduced here.
- Alternative use of a sugar cube, about using a sugar cube to remove bits of paint.
February 2015 about:
- WSPR; since this is mostly general information which is available elsewhere, it's not reproduced here.
- Signal/noise ratio of digital amateur modes, explaining the Eb/N0 measure for signal/noise performance, and comparing several amateur modes using this measure.
- Cone-shaped roller inductor.
- Grounding of MiniWhip and other active whip antennas.
July 2015 about:
- Radio propagation during a solar eclipse; see http://wwwhome.ewi.utwente.nl/~ptdeboer/ham/eclipse2015/.
- The Gyrator.
- Integrating signals, and some moonbounce history.
- A ferrite mystery; will be reproduced here along with the solution in the next installment.
December 2015 about:
April 2016 not yet available
August 2016 about:
January 2017 about:
- Rain radar on 24 GHz, not reproduced here because it's mostly based on this (in Italian).
- Transformer-coupled source follower in an active antenna
- Smart frequency doubler, not reproduced here because it's essentially based on this.
- Smart passive receiver, not reproduced here because it's mostly based on this.
- Passive FM receivers
- Measuring tape as antenna material
- Common-mode chokes, not reproduced here because it's mostly a summary of this.
- Nano-crystalline toroidal cores
April 2017 about:
January 2018 about:
May 2018 about:
- Relay contacts and "fritting"
- Recent progress in amateur VLF experimentation
- The polyphase mixer used in the Airspy HF+
- Automatic tuning of digital noise reduction
- Musings about a portable LCD TV screen
October 2018 about sideband asymmetry in the Luxembourg effect; not yet available here, but based on this.
May/June 2019 about: