Double tube Williamson output

For power up to 15W, the response from 10 Hz to 50 MHz is flat. At 15 MHz, the total harmonic distortion of the full power output is 0.25%. The output stage uses a connecting tube in the push-pull type as a triode. The input transistor can be any Philips BFQ10–16 or equivalent replacement, such as the Siliconix E401.