Talkback Mod
Talkback can become distorted if these radios have been "peaked," and there is no cure because the talkback just amplifies what goes to the RF section. Try adding a 470k ohm resistor from junction of C154/R207 to the junction of C187/R235 on the solder side of the board. This will also give you clean talkback on SSB and FM. Try different values of resistance to get the amount of volume you want. The less the resistance the louder the talkback will be.
73Disabling Talkback
DX 33HML Disconnect wire located in TR30
DX 44V Disconnect wire located in J15
DX 66V
Disconnect wire located in J15
DX 73V
Disconnect wire located in J15
DX 77HML
Disconnect wire from resistor R244
DX 88HL
Disconnect wire located in R189
DX 99V
(original type echo board) Disconnect wire located in TR35
DX 99V
(smt type echo board) Disconnect wire located in J15 next to R244
DX 11B
Disconnect wire from diode located in R244
DX 22B
Disconnect wire from diode located in R327
I have done it to all of my ept3600 rci radios.I have a local guy that does this mod to every radio that goes out the door from his shop. So I'm very familiar with this mod.
~Cheers~