Features: The finished board comes with a heat sink but does not include a cooling fan. A cooling fan is recommended for daily use. Several boards have slightly different power supply interfaces and component locations, with the same circuitry and performances. The specification of the power connector DC13.8V block A is 5.5X2.1, positive inside and negative outside. Universally interfaces B, you can solder the power cable directly to the pads, can withstand more current. The shortwave amplifier board can only be used for shortwave amateur radio single sideband ssb, CW power amplification, not suitable for other purposes. Specifications: Frequency: 3-28MHz Input Power: 0.1-3W Output Power: 30W (7MHz) 13.8 volts with 0.2W to promote about 15W output, the chirping 2.5W to promote about 30W Operating Voltage: DC13.8V Operating current: maximum about 6A Transceiver switching : Automatic pcb Size: about 60x100mm/2.36x3.94in Type: A： DC5.5X2.1 Block Finished Board /B： Universally Pad Finished Board Package Includes: 1PC Short Wave Amplifier Board note: Due to the problem of lighting effect and shooting there might be tolerances in product, please understand. Please allow 0-2mm error due to manual measurement.