søndag den 2. november 2014

1 kW dummy load with fan cooling

I was looking for a big dummy load in connection with my EME-project. Output 1 kW at 144 MHz from the SSPA cannot be terminated into small dummyloads. I needed a "grown up" load.

I decided to build a dummyload with active cooling. A big heat-sink was found on Ebay.de. It was converted into a heat-duct and 2 large fans were fitted at one end. The heat duct was mounted vertically so that cold air can be taken in below, and hot air will be blown out on the top.

Two 800 W resistors, each 100 ohm, were connected in parallel to serve as one large 50 ohm resistor. The resistor array was covered by a metal box to avoid RF radiation. A heat sensor was employed so the heat sink temperature can be displayed on an external digital voltmeter.

1 kW dummy load. Two large fans provide cooling.
The dummy load works to my satisfaction. The frequency range is 0 - 500 MHz. The SWR at 
144 MHz is 1.3. I can now run SSPA tests at full power for long periods of time without overheating.

73 from OZ1BXM Lars Petersen
Homepage: oz1bxm.dk

1 kommentar:

  1. Islamabad is a delightful and present day city of Pakistan. Islamabad Rent a Car It is the capital of the nation and regularly fills in as the section point for the greater part of the travelers. In the event that you are in Islamabad, the most ideal approach to investigate the city and its way of life is by moving in an auto. Bahria lease an auto is the best place for you to get an ideal auto for your vehicle needs while you are in Islamabad.