Mains transformers
Lundahl manufactures a limited range of C-core mains transformers, primarily for tube amplifiers. These transformers are best used with bridge rectifier circuits (four diodes), but some transformers can also be used with full wave rectifier circuits. ? The hybrid power supply principle provides a bridge rectifier circuit using classical tube rectifier tubes in combination with modern diodes. The transformer primaries are connected in series for 210 – 250V and in parallel for 105 – 125V. Secondary voltages are calculated for 230V / 115V primary voltage. The secondary voltage listed are no-load voltage. Voltage drop because of load can be calculated from transformer copper resistance and load current. For optimal use, about 75% of power should be taken from secondary 1. In Lundahls mains transformer range, a small deliberate C-core air-gap is used to prevent from core saturation caused by any DC unbalance in the mains outlet.
