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Old 11th May 2022, 10:05 pm   #6
Sideband
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Join Date: Oct 2003
Location: Croydon, Surrey, UK.
Posts: 7,548
Default Re: Homebrew tuner from Richard GM thread

I had a quick look inside the amplifier unit today. Unfortunately the pictures I took are not very good so I'll get some more later. However it uses silicon transistors throughout, the output pair are BD121. It has a separate pre-amp/tone control unit built on .15matrix veroboard and the main amplifier is built on .15 matrix plain perfboard. I was hoping to get some idea of build date from any electrolytics with date codes. I have found one which might be March 63 (63/3). However I think 1963 would be a bit early for silicon transistors. It looks late 60's to me. I've not yet identified the smaller signal transistors...maybe that will give a clue. They are plastic encapsulated in the pre-amp.

More when I've delved inside further.
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