I have a dr-570 tht has no tx or rx on UHF. Vhf works fine. I started by loocing in the service manual.
The manual says to adjust TC1 for 1.8 volts while monitoring TP3.
Then adjust TC2 for 3.8 volts tx.
The voltage on TP3 is .600 mv. Either adjustments does not affect the reading at TP3.
I have to trace down the schematic and figure out the voltage supplies.