Subject: How to Modify a AT-600/HTX 204 !

Keyboard

With the radio on.
1. Press "F" and "0" to enter main menu. Press "14623" consecutively until you here the confirmation beep. 
     Turn off the receiver and turn it back on. Now the receive modification is done.
2. Press "F" and "0" to enter main menu. Press "1462311289"consecutively until you here the confirmation 
beep
     Turn off the receiver and turn it back on. Now the transmit modification is done.

Hardware (CAUTION: It voids the warranty.)

1. Open the radio and remove Q220 from the keyboard. 
     Turn on the radio by pressing "F", "LAMP" and "5".
2. Open the radio and remove Q220 and Q221 from the keyboard. 
     Turn on the radio by pressing "F", "LAMP" and "5".

If you have version 1.00 + 1.10 (Radio Shack's HTX-204 included):

Keyboard 1: RX 100-200, 330-500, 830-868, and 896-999.995 MHz; TX same
Keyboard 2: TX 100-200, 400-500 MHz; RX same

Hardware 1: RX 100-199.995, 330-499.995, 830-868, 896-999.995 MHz, TX same
Hardware 2: TX 100-199.995, 400-499.995 MHz; RX same

If you have version 1.20:

Keyboard 1: RX 100-200, 330-500, and 896-1000 MHz; TX same
Keyboard 2: TX 142.5-149.5 MHz; RX same

Hardware 1: TX 138-174, 430-470 MHz; RX 130-174, 350-470, 869-999.995 MHz. 
Hardware 2: TX 100-200, 400-500; RX 100-199.995, 330-499.995, 896-999.995 MHz.

If you have version 1.30:

Not available at present.

                        Cellular Bands Information for ADI-600

Mobile Cellular (823.9275 - 851.0000 MHz)
     - Unable to receive
Portable Cellular(868.9375 - 896.1125 MHz)
     - 913.0375 - 940.2125 MHz (FM Mode)
          - Set frequency step to 30 kHz after you find one frequency that is used for the cellular in your area. This will work perfect.