Old radios, like the E.F. Johnson Messenger 1,2, or 223 came without a grounded chassis (3 prong cord). The chassis can become live, and it had a/c floating on the chassis already. I observed sparks when I put my coax to my meter's chassis, also I was feeling a "bite" from the chassis!
Here are the schematics for all 3 models' power supply.
[photo="medium"]4890[/photo] .
Here is how I currently have an E.F. Johnson Messenger 1 wired up:
[photo="medium"]4891[/photo] .
I have already removed the vibrator circuit as this unit will not be ran off 12v, add the fact that I have already installed a 223 transformer into the 1, so the power supply section almost matches the 223, minus the addition of the 3 prong cord and subtraction of R69, C51.
Thoughts, questions, concerns? Should I add C51 and R69 back in?
