12 Meter Modification

The CHIPSWITCH   IC is programmed to allow for a base frequency coverage of 24.800 to 29.999 MHz, 12 through 10 meters. However, because of limitations in the original UNIDEN designed Phase Locked Loop (PLL) circuitry, most radios will also require additional 12 METER MODIFICATIONS to actually transmit and receive at 12 Meters. Just the installation of the CHIPSWITCH chip will allow you to 'dial in' frequencies down to 24.8 MHz, but most radios' PLL circuits will lose 'lock' below about 25.5 MHz, thus rendering transmit and receive inoperative at these lower frequencies. The optional 12 METER MODIFICATION provides transmit and receive operation over the full 24.8 to 29.9 MHz range of the CHIPSWITCH microcomputer chip. The 12 METER MODIFICATION consists of installing a number of small components that are soldered onto the backside of the PLL / MICROCOMPUTER circuit board, the same board that the CHIPSWITCH chip is installed on. Various electronic test equipment is then needed to adjust various circuits. 

The  CHIPSWITCH   12 Meter Low Frequency Password is no longer
 needed for 12 Meter operation.  10 & 11 Meters work without the
 installation of the 12 Meter modifications.

  Rogerbird's Modification Web Page describes a do-it-yourself version of 
the 12 Meter modification procedure. His e-mail address is listed on
http://www.chipswitch.com/Sales-Install.htm