My Unusual (REDESIGN) DIY 450 Watt RF Dummy Load - Part 3

[@billygamer3941]

The attainable improvement by the design change between version 1 and 2 is astonishing. Very instructive. The workmanship is very good. Thank you.

[@rfburns3472]

Thank you Billy for your kind remarks!

[@deanberglund2332]

I played your previous 2 videos on Zoom to some ham radio club members and one of the guys commented on exactly what you are referring to on the shield part of the dummy load. He suggested wiring it straight up from the heat sink to the SO-239, which I then did when I built mine. I haven't tested it yet on a NanoVNA but there should be an improvement because it doesn't have to travel through the stand offs. I think I'll be happy with my build. I also won't be using it for higher power than maybe 50 watts on UHF either. I am thinking of suggesting this dummy load build for a future Build a Thon project.

[@rfburns3472]

Hi Dean. Let me know how your tests work out. I extended the 4 screws on the SO-239 to make a pressure fit on the flange resistors just below. I was somewhat disapointed to find thre was no improvment noted on the NanoVNA. It's possible the copper clad bridge connecting the 4 spacers to the heat sink was still having an affect on the measurement's even with a more direct connection. 73's

[@rfburns3472]

Sorry folks for the abrupt ending. I set the camera down and must have hit the stop recording button!

[@andrewbarnett84]

Very good exactly what I had in mind. I have an Anaren 450 Watt 50 Ohm termination like yours. Just looking for suitable heatsinks now. 73 Andrew ZL2ALW

[@rfburns3472]

Thank you Andrew! Take a look at some of the CPU coolers that could be used for a heat sink. Just be careful when mounting the flange resistor to not drill into the "heat pipes" that run through the sink's mounting plate. I like this one for dissipating lots of heat. Might be overkill however. www.amazon.com/Thermalright-Peerless-SE-Aluminium-Technology/dp/B09LGY38L4?source=ps-sl-shoppingads-lpcontext&ref_=fplfs&smid=A1BCKG4OE2CKC4&th=1 The problem with this one is you cannot drill into the plate due to the 6 heat pipes running through it. Some other means of pressure mounting must be used. Let me know how your project works out. 73's

[@petercharleslaurent]

Only for test ... then if you wana test its at your own risk