FM modification for the Wilson T2202SM portable radio, by Karl Shoemaker

The Wilson portable comes stock as a phase modulated transmitter. Since we are not using the receiver for this project only the transmit section will be covered. The front and top controls are show, here.

On the bottom the battery carriage is left out so a few items can be mounted in this area. The dropping resistor keeps the RF power out down, with an LED across it functioning as a PTT indicator, from the voltage drop across it. This gives you a choice to power the radio with the station's (typical) 13.8 or, if you have a lower voltage direct to the other terminals "10.4" input. If you run the radio without a drop resistor the final transistor runs too hot under continuous duty. The right imagine is the schematic of the transmitter's Frequency Modulator addition. The audio input TLP is a 1 dbm. PTT is an active low (to ground). If you need a larger image, click on the center of it.