By Jim, N6TP The recent interest in WLW (500 Kw in the 1930s) reminded me of the technology that went into producing a good quality high level plate modulated transmitted signal. You may remember prior to rule change of 30 years or so by the FCC that the maximum power limit (where licensed) was 1,000 watts input. This meant that if you were running high level plate modulation, you had to have 500 watts of RMS audio power for 100% modulation. You will recall that the secondary of the modulation transformer was in series of the B+ to the final tube(s). […]