How to Build A 130 Watt Dummy Load for HF Ham Radio

[mts0628]

I made the same dummy load but I added a diode, a capacitor, and banana jacks so I could calculate power output of my rigs. These dummy loads are very handy and simple to make. Oh I used mineral oil because I did have some on hand (for beekeeping) but any oil that won't break down at these operating temperatures or go rancid will work. I thought about adding a PIC to calculate the wattage but I never got around to it. Nice job!

[MrHeffernan11]

Is that Seriously Giveing out around 50V??? And also How long will this Masterpeace last?

Great Vid 10 out of 10 :)!

[69furball69]

@MrHeffernan11 That's 50 Ohms resistance, a perfect match for a ham radio antenna output. The resistors dissipate the rf energy instead of transmitting a signal. This allows you to tune your radio with full power output without causing interference.

It should last until the can rusts and when the can rusts buy another and use the lid assembly you have with the new can, so virtually forever as long as you don't burn it out with too much power.

[MrHeffernan11]

@69furball69 What If u Coat the Tin in Rust proof Paint? And also How do i Hook this up to the Lest say Radio antenna output

[CodfishCatfish]

If you use a BAV21 Diode from a terminal binding post to a black terminal binding post which goes to the paint tin as GND and then a 250v 0.01 uf cap across the binding posts then you can measure wattage by measuring the voltage and say a 0.4v drop across the diode and adding this later. say you measure 49.6v + 0.4v and sqr/rt of 2=1.414 (50v/1.414=35.36vRms) 35.36x25.26= 1250.33 and divide by 50 ohms Imp = 25watts simple no need for wattmeter.

[salat]

Mh.. nice work, but have you heard of the salt water dummy load?

[69furball69]

@salat Heard of it, yes. Not to say I know anything about them in particular.

[smilerjeff]

excellent video .. hardware store here i come :)

Jeff M1BCM

[69furball69]

@smilerjeff Thanks for watching.

You're 5 and 9

Good luck with the project!

[websterzip]

I'm having a problem finding a supplier of 1K 3W resistors. Both within my local area and online. Who do you use?

[69furball69]

@websterzip search for 'k4eaa' and if you add a 'dotcom' after that call sign you will find ken's web page, from which he sells the resistor kits.

[websterzip]

What is the name brand and type of meter are you using to test the DL at the end of the video?

[69furball69]

@websterzip Hi,

It's just an ordinary multimeter, I think it is a local offshore import store-brand that was on sale for about $8.00... kind of like the Canadian version of Harbour Freight in the US.

[mts0628]

Great video! I added a diode and a capacitor and was able to measure voltage and then calculate power. Mine though is not as sealed as yours so I can't knock it over or I'll have a mess. I also used a SO-239, which admittedly isn't the best connector but you know...

[69furball69]

@mts0628 Thanks!

I run a power/swr meter inline before the DL so I did not bother with the diode for power measurement.

As for the sealing, the connector itself will leak if the can is tipped over. The connector is basically a metal cylinder with a piece of dielectric/plastic and the centre conductor inside it so it is not really sealed that well.

You can see when I pull the test lead off the connector there is a drop of oil on it from pressure pushing it out... :)

[GeoN0JRJ]

Excellent Video! Thank you!

[69furball69]

@GeoN0JRJ Thank you for the comments.