Illuminating meters
A simple and effective method of providing illumination for most of the standard panel meters is to cut a small slot in the top of the meter case, as shown in Fig. 1, and mount a pilot lamp directly above the slot. The meter scale will have to be bent back slightly and the slot covered with transparent cellophane or plastic material to keep dust out of the instrument.
Fig. 1. Cross section of the meter showing special illumination slot.
William Vandermay, W7DET.