This set uses a LC7131 PLL and is not easily modified, unless you add a crystal oscillator !

I know that the SD 310 radio's i have seen all had an oscillator already, if this is the case then change the crystal to any of the values shown for the common bands, or use your own crystal frequency for a different range such as 28 MHz.

The first thing that you need is a crystal oscillator, you can use this one.

Once you have built your oscillator, you will need to get the crystal for the frequency range you want to operate on,if you want to operate on more than one band you will also need to add my crystal switch , this will need to be added on to the oscillator where the crystal would go.

These are the most common crystal frequencies:

Band.........................................Crystal Freq

26.515 (low band)...........9.790 Mhz

26.965 (mid band)..........10.240 Mhz

27.415 (high band).........10.690 Mhz

You probably won't be able to have more than two bands, as most AM set's are not able to cover that wide a frequency range without some major alterations.

On to the juicy bit !

Open up the radio, locate C15 (it is close to the 10.240 Mhz crystal) and remove it, then attach the output of the crystal oscillator on to the side of C15 that goes to T2, then attach all other wiring as required.

The new crystals will need to be calibrated so that their bands are on frequency.

You will need to adjust the VCO and the TX/RX alignments to cover the new range.