This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
Freqtripliermade of triodes. Freqtripliermade of triodes basic design for frequency tripler which has has things like screen grids and bias supplies removed en Adrignola CommonsHelper Hapa en English Hapa Original upload log page en Freqtripliermadeoftriodes Hapa bytes no basic design for frequency tripler which has has