Note : The boards are now in tin-plated surface. This is an sale of the bare PCB of the kubota regulator , high voltage version, for tube amplifiers. Due to the high current capability, the power supply can be used for preamplifier or power amplifier HV power supply. Kubota regulator is designed to have lowest impedance in the audio frequency. Bench tests have done to find Kubota regulator ( low voltage version) to be as good as SLC battery and far better than normal regulator ICs. It is also renowned for high speed and low noise. It is one of the best regulator circuit for audio application. This Kubota HV board also includes a soft-starting feature by means of a 5Z4P tube. When power up , the voltage with rise up slowly so no surge current to attack your precious tube amplifier. If soft-starting function is not required, the 5Z4P tube can be by-passed. Specifications : Input voltage : 200 VAC to 350VAC Output voltage: 200VDC to 300VDC. Noise : 0.1mV Maximum current : 500mA We provide schematics and part list to the buyers by EMAIL. PCB thickness : 2mm. Copper thickness : 2 ounce ( 70um -- four times normal copper thickness!) PCB dimension : 100mm x 77mm. The pictures of the assembled boards below are for reference. The listing is for one piece of bare PCB. We do air shipping worldwide at US$5.50. We welcome combine shipping. Powered by SoldEazy