How to remove the Dual Front End (DFE)

option from a VHF GE MII mobile

By Scott Zimmerman N3XCC



Normally a dual front end is not required for repeater use. Since there are many dual front end radios available on the market, one may want to remove the dual front end option from a GE radio when it is being converted for use as a  repeater.


Background information:

It would seem easy to remove the second receiver, one simply needs to disconnect the second receiver deck and associated cabling. This is not the case. Simply removing the wiring will lead to poor receiver sensitivity. This article describes how to properly un-modify the GE MASTR II receiver when removing the dual front end option.

The (Un)modification:


Remove the second receiver chassis and wiring from the radio set. This casting can be kept for use as a spare if desired. Some DFE radios came with preamps in both receivers. Be sure to check your chassis before simply discarding it!!!


IF/Audio/Squelch board:

        Simply remove the LO Injection coax from the circuit board.


Oscillator/Multiplier board:

        Simply remove the jumper from H1 to H2. This jumper is located on the underside of the board.

        To assist in identifying this jumper, one end connects to the control board pins; pin 13.


Mixer/IF board:

        Remove R2302, a 680 ohm resistor and replace it with R523, a 47 ohm resistor.

        Remove diode CR2301 and replace it with C529, a 1000pf capacitor.

        Remove R2301, a 22k resistor. It is soldered in holes H5 & H6.




Re-tune the radio set as outlined in the manual. You should now have good sensitivity.

Research done by M. Scott Zimmerman N3XCC
HTML Copyright©  5/11/2006,  M. Scott Zimmerman N3XCC
Page last updated 5/11/2006 N3XCC