Having built a number of vacuum tube output transformer-less (OTL) amplifiers in recent years, it seemed as though it might be a good idea to try combining older with newer technology and using both ...

The circuit was designed to create a line preamplifier by acquiring the use of double triode tubes. The circuit comprises of three parts, the main preamplifier circuit with tubes, the input selector ...

In the first three installments of this series, we discussed whether or not an old transmitter was even worth fixing, followed by some techniques I ve used to repair high-voltage power supplies, ...