I started to replace my blown meter lamps with LEDs. Before I replaced them I decided to check the voltage across the lamps. To my surprise instead of 12v or so expected my meter is showing 24v across each meter. I decided not to replace the lamps until I figured out what is going on. Anyone who can help me? This is an older al-811.
The voltage driving the meter lamps is unregulated. The DC supply uses a voltage doubler circuit and shows a very high drop between no load and regular load. It can be as high as you observed when the amp is not keyed and the lamps are not drawing current. It will drop substantially when the lamps are drawing current and a little more past that when the amp is keyed and then modulated.
The 12V bulbs suggested here will have a long life, longer than the nominal 8V bulbs also commonly available: Suitable meter lamp replacement suggested in a different thread: http://www.mcmelectronics.com/product/25-455