I bought a Ranger EB-2015 board and tried it in my 520, and it didn't work right. The audio was so low. Others on here were saying it had to do with the way the high impedance mic is wired. I took it out and put it in my Cobra 25.
Not talking about the echo board that is all set and works fine.(If you intend to use an RK56 or an Astatic 636 noise canceling mic we must be informed. More than likely the mic amp circuit of the radio will have to be modified in order to achieve the correct percentage of modulation.)
Great sounding board, not like the news ones now, I had it in a Euro3900 sounds so clear now I have it in a Cobra 25 and it sounds great.I put one of those boards in a Cobra 29. Best sounding echo. Hard to find. Its the 50B board I believe. Don't buy the new version you see out there. Its like a Connex Ranger 2015 echo board. Supposed to be a remake of that board. Big disappointment. Voltage temperamental and the echo is very touchy.
That's one of the issues everyone has with this new model 520, no one can find the schematic for it. CB Tricks has it for the older Philippines model the board has change alot since then. Even if you look at the file for alignment for this radio it don't match what you see on CB Tricks. I'm no tech but I have to say I'm having fun messing around with these radios. But soon I'll have all the testing equipment I need from reading up in this Forum.if you have a schematic for the 520 radio might help some one to look at it.