About this site

I used to maintain a site www.thermionic.org principally to interest people unaware of thermionic devices (electronic "valves" or "tubes") in this excellent, if old, technology. Even in the 21st century there is much fun to be had and good work to be done with these devices.

As I'm also interested in semiconductor based electronics (both analogue and digital) I have started this more general site which includes projects using semiconductors.

Although I have done little to report here yet I am particularly interested in the field of "retrocomputing" - that is old style computing. Retrocomputing can be done using the original hardware, modern FPGA (re)implementations of old systems or in software simulators running on a modern day computer, typically a PC or MAC.

Although this later approach generally provides the best performance and requires no extra hardware I'm only interested in the first two approaches as they (to me at least) are much more tangible and a little more "old school".

Site disclaimer

This is an amateur website (in every sense of the word :) and the opinions and information herein are in no way warranted, either directly or by implication. The webmaster shall in no way be held liable for any damage, loss or injury, directly or indirectly relating to anything on this site.

Your webmaster certainly does not know everything (some would say anything :) and so if you have any comments or corrections please email me at: To use this email address you will need to re-type it

I'm writing the site HTML by "hand" using a text editor and so the site does not have many exciting features. Just so long as it isn't broken I'm happy - I hope it works for you.

This is not intended to be an exclusively Amateur radio interest site but currently the projects are all radio related. Over time, I hope to add as much content as possible. Please enjoy!

Safety with high voltages

The majority of valve circuits use voltages that may cause injury and death. If you are not experienced with such devices and techniques, please start with low voltages and gain experience before attempting anything involving higher voltages.

It is possible to make equipment with no exposed live parts; for reasons of safety this approach is to be recommended although some pictures shown here feature equipment with exposed live parts. This is a style of construction adopted by many people interested in early radio circuits but does require great care in testing and use.

A good place to start with low voltage valve circuitry is the website of Kazuhiro, JF1OZL. His most excellent site has a quite a number of valve circuits. You can find his site here.


All content on these pages is copyright © Andrew Burge, 2001-2008, unless held by others for which no rights are (or can be) transferred. The copyright material held here may be freely distributed for non commercial use if attributed. All trademarks and the copyright of others is gratefully acknowledged.

About me, electronics and Amateur (or 'Ham') Radio

My name is Andrew Burge and I have been a licenced Amateur Radio operator since being issued the callsign G6ALB in 1981. Despite becoming inactive in Amateur Radio during the middle 80's, I got enthusiastic about radio again in the mid 90's.

When I decided to get back on air, I started with a (solid state :) 6m (50 MHz) "transverter" kit and drove this from an old FT901 HF transceiver I bought. I soon found some friendly locals in the shape of Mike G1SYT & Steve M1ACB in Ipswich where I lived. Together G1SYT and myself set about learning CW (Morse code) on the air.

I worked many hours of CW with G1SYT (now M0AWS and F5VKM) and despite moving house (and also moving out of 6m range with him) I eventually took both my 5 WPM (Word Per Minute) and 12 WPM Morse tests in 1998.

I was allocated 2E0ARY (an old style "Novice A" licence) after the 5 WPM test and then M0BXT (a "Full A" licence) after the 12 WPM test. The rules have changed quite a few times since then and the Morse test requirement has now been completely removed in the UK. You must now progress through the Foundation and Intermediate class licences to get to the Full licence.

In mid-2009 I decided to return to my old callsign and so G6ALB can once more be heard on HF. I say "once more" since I [and others] took advantage of an anomaly in the licensing conditions in the early 80s caused by a clerical error in some published amendments to the Amateur Radio licence schedule.

During this brief period the distinction between Class A and B licences was temporarily lost and I made a contact with another "B" on Top Band using AM from a Minimitter transmitter. This was very exciting at the time (but it doesn't sound that thrilling now :) The QSL card is still on my wall.

I was attracted to the High Frequency bands (also known in broadcast terminology as the "Short Wave") because it is possible to make effective and simple equipment capable of making contacts over hundreds or thousands of miles using these frequency bands.

There are a lot of websites covering the various facets of the Amateur radio hobby. A good search engine should provide you lots of interesting hits.

I wired up simple valve circuits as a teenager and I still have the valves I used. Most of these still work too - despite the passing years. I write communications software for a living and so old electronics provide some good technical escapism.

back to index