1) To convert 8Ch. unit to 16Ch unit. These are the 'same' radio. Only the 'encoder' is different. The 8 Ch encoder knob has a small black plastic skirt' with a 'tag'. Remove the 'skirt' component and file-off the tag.
The encoder now rotates through 16 channels. A GP300 16 Ch. 'Escucheon' is available to order as a spare part/replacement. This is the plastic screen-printed' plate which sticks on the top of the radio showing the various controls.
2) To bring down the frequency coverage below 146 mHz - so as to cover the amateur 2 meter allocation. This is done when using the RIB (radio interface box/line) and a PC programme of Motorola's. When typing in the required amateur (145mHz) frequencies in the RX or Tx windows...the radio refuses to accept 'out of band' freq's. To overcome this...use the PC keyboard 'Shift key' when entering the 'NUMERALS' only. This will display as the secondary characters of the key pressed. Don not worry - this is normal. Then, when entering the decimal point...release the 'Shift key' and enable the 'full stop',(dot). Then...to enter the remaining numerals which follow the decimal point...engage the 'Shift key' again....to complete the entry. Having done this....press 'Enter' to lock-in the new frequency. Some re-aligning may be necessary to peak the radio onto the lower area amateur allocation frequencies. Good luck.