UNIDEN GRANT-XL: Channel Conversion
1. First locate Pin 14 of the MB8719 PLL chip on the bottom side of the circuit board. Using a ex-acto knife, carefully cut and isolate Pin 14 away from the circuit board run. Next solder a 4.7K 1/4 Watt resistor across this cut as shown in the diagram above.
2. Next mount 3 SPST Toggle switches in a convenient location . Be sure to wire the switches up as shown , and to solder each wire carefully. Once all the wires have been soldered to the switches and to the circuit board as shown, check all solder joints before proceeding.
3. Now with all three switches in the down position you will still have the normal channels. Refer to the 8719 Channel chart on the following page for the switch positions and their associated channels.
Note : The above modification is shown using added SPST switches. This is not a requirement for this modification to work. This is shown for reference only. You are always free to use any switches that are available on the radio for this purpose also.
Switch Channel Chart
Rotary Channel Conversion
1. Obtain a Double Pole/ 6 Position Rotary Switch. Be sure to get the Break Before Make type. You will also need 2 small signal diodes (1N914, 1N4148 or Equivalent), a piece of 5 wire ribbon cable long enough to reach from the switch to the PLL chip connections, and 1 4.7k 1/4 watt resistor. Next solder the diodes to the switch as shown in the diagram above. Be sure that the cathode ends (Banded) are as shown once you have completed this step. The diode that connects between Pin 4 & Pin 5 should have the banded end to Pin 4 and the diode the connects between Pin 1 & Pin 4 should also have the banded end to Pin 4.
2. Next locate Pin 14 of the PLL and using an ex-acto knife carefully isolate Pin 14 as shown above. Next solder the 4.7k resistor across this cut in order to allow Pin 14 to operate at its normal state. Once this has been done you may connect the ribbon cable to switch - prior to mounting in its permanent location. Be sure that the wires are connected as shown in the above diagram. Once that you have mounted the switch you may then make the connections to the PLL chip as shown above . Re-check all your connections before turning the unit on . The channel chart on the next page shows your new frequencies. Check all positions of the switch for these channels. Some adjustment of the VCO coil (L19) may be necessary in some cases for full channel coverage.
Rotary Channel Chart