this dummyload is used for developing and testing high power LDMOS RF-amps. It handles ober 2kW power up to the 6m band. It is very small because it uses water cooling (only 200x120x10mm). www.dj0abr.de
This is an awesome design and tails nicely with the amp as well. Thanks so much for your efforts. I can't wait to get started on mine for my KX3 foot warmers. Thanks again. Bill / WB9FFG
1) copper and aluminium is not the best pair, especially with water nearby. 2) what about the drops of solder inside the channels: it will make resistance to water flow. 3) I'd also recommend making additional fixture to the resistors with screws and bars, just in case, so if anything goes wrong, the resistors would not dropped out, but internal resistors structure will anyway be melted, so now I think, no need to do it.
This is very nice! Why could you not place a gasket in between the soldered plates and screw them together instead for easy maintenance? Car water pumps do it every day for years and years they work.
These resistors usually have limited voltage ratings , so the amp must be very well matched to 50 ohms! Also dissimilar metals in the presence of cooling water is a recipe for corrosion! Take care!!
How do you solder these resitors on this massive block of copper??? You need a few kW soldering iron or gas burner for that. Ahh - i see the kitchen stove did the work :-)
right, hi. Most important is to give a few bucks to your wife for shopping. If she left home, you go into the kitchen and heat up the copper block until the solder melts. This is a critical temperature because the ceramic case of the resistors will start floating when the solder is melted and therefore must not be touched.
yes oke,i orderd 4 resistors (with one connector) and want too use 2 rows parralel and then connect them in serie(of course with some kind of insulation?)..in this case can we handel one kilo watt??thanks for your feed back!!!
Resistors with one connector are a problem because you need insulation. Better to use resistors with two connectors and solder it directly on the copper plate. In my first version I tried it with insulation, but the resistor burned. You get 50 ohms / 250 watts resistors with two connectors easily from aliexpress for low price. You can also use two resistors with two connectors and two resistors with one connector, which gives you a very good ground connection.
yes oke,i saw those with the double connection...believe it ore not but shippmant too the Netherlands was 60 euro and too Germany 1,74 euro....i m going to make a smale one with one resistor(only for 200 watts and a few seconds).and will order those with the double connection and let them ship too my german collega....thanks for the info harry...
Harry - you sure like the water cooling!! Nice work. Here's a similar air-cooled dummy load I made back in June: www.qrz.com/db/N4GA Bottom of the page. Take a look! Rob
자세히는 못 봤는데 ㅎ 내부에 물과 반응하지 않는 코팅을 했나? 안 했나? 예를 들어서, 수산화알루미늄은 잘 자랍니다.. 금속은 다 그러함. 수냉방식 펠티에냉장고 만들어 보니 그렇더라구요. 가공하실 분 참고를 하소서. 그리고 원터치피팅은 기체용도임 그 구조와 리테이너의 재질상 액체용도로 쓰면 단명함. +덕분에 공정 잘 보았고 대단히 고맙습니다.
I didn't look closely, but is there a coating on the inside that doesn't react with water? didn't you? For example, aluminum hydroxide grows well. All metals do. It was like that when I made a water-cooled Peltier refrigerator. Please refer to the person who is processing. And one-touch fittings are for gas use. Due to their structure and retainer material, they are short-lived when used for liquid applications. +Thank you, I saw the film and thank you very much~~~ !!!!
