Strictly use 13.8V DC. Connecting the unit to a 24V supply (common in some heavy vehicles) will cause immediate damage to the internal power regulation circuits. Antenna Matching:
Many users don't realize that the "Service Manual" often includes a download link for (a Windows XP/7 utility). This software allows you to: qyt kt-7900d service manual
Warning: Without proper test equipment, do not touch the PLL coils. Strictly use 13