Complex sentence: For antique radio equipment, a "pre-condition" of older electrolytic capacitors may be recommended, by applying the operating voltage for some 10 minutes over a current limiting resistor to the terminals of the capacitor.
Split into simpler sentences: For antique radio equipment, "pre-conditioning" of older electrolytic capacitors may be recommended. This involves applying the operating voltage for some 10 minutes over a current limiting resistor to the terminals of the capacitor.