I built my Hilltopper 40 way back when, and built in an additional feature. The rig has no power switch, so I added a “power on” LED. That way I won’t forget to disconnect power to the rig if I walk away for awhile. Useful if you are running battery power!
See pictures. The “window” square on the top panel is a great spot for the LED. I drilled half way through from the back side to clear the metallization. You can drill all the way through if you wish. Use whatever color LED you want;, I used a green one from my junk box. Mount LED on the cathode of reverse polarity diode D1 so it just reaches the hole you drilled. Add suitable dropping resistor to give you desired brightness/ current. I used a 3.3K 1/4 watt resistor. The left side of the DC in jack is a convenient ground point. See second photo.
Paul Goemans WA9PWP