Audio Projects for Amateur Radio Stations
Around the shack or mobile in a vehicle audio amplifiers are needed for various functions. The example projects described below address this requirement mainly from a collector's point of view. For other ideas there is a lot of information on the web using modern IC amplifiers, no need to add to that here.
- An easy project to add a speaker amplifier to your sound card or phone outputs→ A Simple Audio PA, Text, Diagram and Picture
This little project makes use of unique features of germanium output transistors to make a very simple speaker amplifier. Uses computer, shack or vehicle +12VDC. No PCB needed, built over the weekend and works fine! Several units were built.
- Collins Radio 76F-1 Amplified Speaker→ Rebuild of a Speaker Unit, Pictures, Comments and Diagram
This is the classic military radio speaker but with a twist: it has a built-in amplifier. However the original parts are difficult to get and this project shows a solution that provides the needed amplifier without those exotic components. It is used with a 671U-4 exciter/receiver.
- Autophon BV83 Intercom Amplifier for Receivers with Line- or Headset outputs only→ Amplifier and Power Supply, Text, Pictures Diagrams
For my historic receiver display a speaker amplifier with high and low input impedance was needed and - no surprise - only an antique unit would do. Here is a detailed description of how this project using a military unit was implemented.
Audio Projects for Home Entertainment
For more years than I care to remember I've been tinkering with audio amplifiers to listen to vinyl records, tape decks, FM receivers or to provide music for an event. My first unit was a pair of 6L6G tubes with big transformers providing some 40W into open frame speakers built in 1960 for a school event... This project was followed by a classical 2x EL84 full amplifier - later converted to stereo - and the 6L6G unit upgraded to a full amplifier. All the while tinkering with preamps, tone control, single ended amplifiers etc. slowly converting from tubes to transistors and ICs.
As there has been quite a revival of tube amplifiers and - quite apart from the "audiophile" group - many people are interested in building such units, there follows some information on projects being done here using sometimes recently available nice PCBs from China combined with quality components and transformers obtained from the EU or sometimes from my stock. Where available the sources of these materials are listed. There are several projects and I try to describe them as they are completed:
- → Amplifiers:
- PP Stereo Power Amplifier using two pairs of EL84 tubes, 10W output transformers (from Germany), magic eye display and a fully regulated HV supply with DC heaters for all tubes.
- PP Stereo Power Amplifier using two pairs of 6L6GC, 20W output transformers (ex-Pioneer) and regulated HV power supply and DC heaters.
- My "crazy project": PP Stereo Power Amplifier using two pairs of GU50 tubes, 40W transformers (from Germany), preamp, phono preamp, tone control, magic eye display and regulated HV power supplies and DC heaters. A big unit in a 19" frame. It's about 60% complete...
- → Other:
- PLL type high stability Tape Speed Control for the Studer-ReVox B77 MkII tape deck.
The links to the documents will follow...
The Small Print
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