Picked up an old RME DB23 6-band preselector with the later push-pull circuit. Lower noise and no harmonics. No beverage antenna for HF ham band receive should ever be used without one. They really cleanup and amplify everything with around 30db of average gain 😀
Below is what the inside looks like from the back then the schematic. It will work with both balanced and unbalanced antennas. Someone drilled out the rivets at one end of each terminal bank and added BNC’s with the skinny shaft threads which wasn’t a bad idea. It’s the most unintrusive way of modifying it for use with coax. I’ve seen these in the past where people drilled big holes and mounted SO-239’s.
Did pick up another one of these preselectors, but its the older model before ElectroVoice took them over. It’s the exact same circuit though. I’m going to polish off the dirt and little paint spots and wax it, then use Brasso to polish and shine up the knobs. Then maybe use a white paint pin to touch up the RME letters on the back side where the lamp faded and turned them slightly brown over the years.