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Disabling Talkback


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  C155/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.

DX 2517 
  • Symptom: 
    • Talkback squeals when mic gain is at max 
  • Problem: 
    • Excessive drive to IC-8 pin 4 
  • Cure: 
    • Replace R-221 with a 200K ohm resistor

Roger Beep Mods

The tone and time of the roger beep on the 10 Meter mobiles can be changed as follows:

  • The roger beep tone is controlled by R181 which is 220K ohms:
    • for a higher tone try 150K to 200K ohms
    • for a lower tone try 270K to 2M ohms
  •  The roger beep time is controlled by C134 which is 2.2uF@16V DC:
    • for longer time try 5uF or 10uF@16V DC
    • for shorter time try 1uF@16V DC


Clarifier Mods

Some people have asked how to make the fine clarifier control track on transmit and receive like the coarse clarifier control. Below are the mods for our 10 Meter SSB mobile models (DX 77HML, DX 88HL and DX 99V) as well as the mod for the DX 2517.

10 Meter SSB Mobiles
  1. Remove R141
  2. Remove D38
  3. Solder bridge J106 pin 54 to 8 volts
DX 2517
  1. Remove D68
  2. Remove R113
  3. Add jumper from R113 to 8 volts


DX 2517 and DX 2527
    • Buzzing or motorboating sound in either the transmit or receive
    • TR602 is oscillating
    1. Replace C602 with a .01uF cap
    2. Remove C608