I don't normally add "courtesy links", but I spend a lot of time searching for datasheets, and these particular links are just too good to refuse:
Datasheet Directory is a site that has been the result of a lot of years of hard work by the author (Jack) to collect many 1000s of datasheets. These he offers for free at http://www.datasheetdir.com/. The site is also organized by function, which makes it easier to find datasheets for any specific application.
Datasheet Archive Search engine for electronic component datasheets and application notes, at The Datasheet Archive. There is also site at http://www.datasheet4u.com where you can find loads of datasheets.
I recently began operating SSB and PSK-31 on HF, but my QSL cards are about 8 years out of date. I was recommended a couple of sites by a friend. They produce reasonable cards at a very reasonable price. http://www.happyQSL.com - The simplest possible way to order QSL cards for very good price - choose your design and fill in the ordering form .
http://www.baltechno.se is A Swedish company, based in Gotherburg. Baltechno have been repairing RC electronics for nearly 20 years. E-mail . I found them VERY helpful obtaining R/C mechanics.
http://www.xs4all.nl/~barendh/ is well worth a visit. They stock those "hard-to-get" RF chips, such as prescalers and synthesizers, etc. They were the answer to my prayers after searching the web for weeks.
http://www.bardwells.co.uk/ is a fantastic component supplier in the UK for the RF constructor. On-Line cataligue too! They even have stocks of the TCM3105. I started using them over 30 years ago.
Antique Electronic Supply company has an on-line catalogue. They can supply almost all you can wish for in valves and valve orientated components. Prices are quite cheap too!
Maplin Electronic components is a good source for modern electronic components at reasonable prices. They do not have a catalogue on line but they will send you a catalogue, even on CD-Rom.
QuartSlab supply custom ground crystals manufactured to your own specifications. Pricing and information on-line.
I only provide rare links that are related to my homepage subject material and only links that are in some way 'special'. If you want a link somewhere then I reccomend you visit UK Amateur Radio quick links
http://www.ham-links.org/ where you will find just about all the Ham radio links I want.
Anyway, here are the 'special' links:
Nick Desmith's homepage at Nick http://www.desmith.net/NMdS/Electronics/, featuring: - 88% efficient SMPS - 250VDC @ 125mA from 12-15VDC input, plus other projects :-)
http://www.xs4all.nl/~pa0fri - Zelfbouw met vooral info over antennes, tuners, lineairs en mods.- Homebrew especialy info about antennas, ATU's, linears and mods, most schematics with english text
http://www.qsl.net/ve3bdb/ - For collectors, restorers and operators, past and present, of the vintage World War Two 'tank' radio, the Wireless Set No. 19". The 19 Set saw action in every theatre of WW2, as well as Korea.
http://www.thermionic.org - Andrew Burge's thermionic site.
ARPR Australia - dedicated to the promotion of Amateur Radio, both in Australia and around the globe.
RSGB Radio .. whachamacallem...? ... the ones that copied Sveriges Sändareamatörer.
a href="http://www.ee.washington.edu/circuit_archive/parts/cross.html">A searchable transistor database, courtesy of Jerry Russell.
Valve (tube) data, courtesy of Trevor Gale.
http://www.intio.or.jp/jf10zl/ Loads of constructional projects. Fantastic!!
SM6LKM QRP corner See 'Optimist 80' DSB TX/RX.