DIY Dummy Load; 250 watt / 50 ohm

Рет қаралды 13,759

3 жыл бұрын

DIY Dummy load, why not build one yourself! I built this one for less than $30
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Пікірлер: 26

@angelo65hog Жыл бұрын

In addition to all other good suggestions, I would have also used thermal paste under each sink to help transfer the heat from the case to sink. The paste will help bridge any gaps between the sink and case surfaces. Probably not too late to pop off the screws and spread some paste on those sinks. Thanks for the video. Good job!

@NorthCountryHam Жыл бұрын

I did actual use thermal paste, it just may not be shown in the video, but definitely a good idea for anything like this. thank you

@ColeDedhand Жыл бұрын

Some recommendations: 1) Use a single larger heat sink. 2) Cut a hole in the case so that you can mount the resistor directly on the heat sink. 3) Use coax from the connector to the resistor and connect the shield to one of the mounting screws to minimize inductance. 4) I also use a copper heat spreaker under the resistor, which may just be my ocd.

@tinkeringwithelectronics Жыл бұрын

I know the pain of getting asked about old KZfaq projects, but am curious how the dummy load performed. That is how hot did it get over how long and how much power? Asked another way, with 100 watts in could it stand 5 minutes without getting too hot (too hot is subjective by you). Anyway thanks for the time in the video and project.

@gixerags750 Жыл бұрын

May as well put a rf sniffer port on that build too..

@harrybond007 2 жыл бұрын

Some interesting ideas presented for a home brew dummy load, I would have centered the resistor in the box and made the wire connector as short as possible. I guess you could also spray the whole thing black, would help radiate the heat. I'm deciding to either make one or buy one right now - thanks for the video

@NorthCountryHam 2 жыл бұрын

I try to build just for the fun and experience

@acestudioscouk-Ace-G0ACE Жыл бұрын

An interesting and useful video, thanks. It would be nice to see the unit under test and use. A follow-up video maybe?

@NorthCountryHam Жыл бұрын

Thank you, I have considered a follow up , perhaps can work on it

@modellerdesign Жыл бұрын

Why such long wire between SO 259 and resistor? No point at all. Only HF?

@xtibi1 2 жыл бұрын

Onto many dummy loads it is written 3GHz. Are good for testing power in 136-500 MHz range ? (radios within VHF and UHF bands)

@germanjohn5626 3 жыл бұрын

Great project BUT, that load will not do 250W for any prolonged time. Your heat sinks are too small. Those resistors need a huge amount of cooling to dissipate the power. If you run them without heat sink and the case only you will burn those resistors in seconds with 250w input. Your wire is too long,it will present an unwanted inductance at higher frequencies.

@NorthCountryHam 3 жыл бұрын

I Agree, didn't figure or plan to use for any extended time, I only have max 100w output in my shack currently, even that I wouldn't run into a load for an extended period. I figured may as well over build for what I need. Thank you for the advice and guidance if I build more in the future I will look for other ways of cooling to make them better

@donaldtune6917 2 жыл бұрын

@@NorthCountryHam di youdrill your holes in heat sink first

@NorthCountryHam 2 жыл бұрын

@@donaldtune6917 I predrilled everything just so didn't damage any fins

@zen_of_I 2 жыл бұрын

What size drill bit do you use for that SO239?

@NorthCountryHam 2 жыл бұрын

@@zen_of_I I used a small bit for pilot hole and then used a step up bit to gradually make hole bigger, I believe I went to 5/8

@josephcooksley3219 Жыл бұрын

Knowing how much heat a 250 watt mains light bulb produces ... it could only be used for very short burst's at 100 watts ... however on 5 or ten watts output from transmitter it will be very much within the scope of the heat disappation with out a fan assisted cooling during testing .. as suggested already using additional Resistors in parallel wojld spread load and Stop possible Resistor BarbQ ... G1XZLZL2SCI

@wesleymatthews137 2 жыл бұрын

Personally, I would have used 4 of those resistors set up in serial/parallel for 50 ohms. There are sets of five for sale on Amazon for $9.99. I would mount them each with heat transfer goop and directly under each heat sink. Nice video. Worthy project for any ham.

@NorthCountryHam 2 жыл бұрын

Great idea

@patricksharimccarthy9495 9 ай бұрын

How are they connected? I can’t find info. I have 4 50ohm on the way. De K2SCH

@wesleymatthews137 2 жыл бұрын

Did you happen to check the SWR after this video? Curious what it turned out to be.

@NorthCountryHam 2 жыл бұрын

Honestly this build was awhile go. KZfaq has been re-posting some of my older videos and I don't remember what the reading was on the SWR

@whatafukndick5660 2 жыл бұрын

@@NorthCountryHam It's only a year old?... did you scrap it already?

@NorthCountryHam 2 жыл бұрын

@@whatafukndick5660 nope sits in my hamshack for use as needed