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HR2600 Modification for increased MicGain

This mod will increase the AM modulation.

The AM modulation adjustment is VR6, which is marked ‘AMC’ on the main circuit board.

To get more, Q15 is the Mic Attenuator, This limits the audio.

 Q15 is located near the front of the circuit board in the center to the left of IC 4, above C64.

 To modify this, remove Q15 and bend the Emmitter leg up from the circuit board and re install.

Put a 1000 ohm resistor in the vacant hole and solder to the board.

 Solder the other end of the resistor to the Emitter leg of Q15.

 

 This will allow more modulation with the ‘stock’ mic, and will allow a Power Mic to truly perform! The AMC control will still function so using a modulation meter you will be able to set it to avoid overmodulation.

Another Mod Suggests Clipping D37 to remove the ALC and AM limiting. I have heard from one user that this mod works exceptionally well.. I have not tried this mod, If anyone else has , please let me know the results.

 Send E-Mail to Rogerbird