100w dummy load resistor

Thread Starter

Hellerx

Joined Sep 2, 2019
4
Hi.
I want to make RF dummy load from aluminium 100w 50 ohm resistor. Is one resistor is enough for making it for 100watt load?
Thanks in advance
 

Attachments

Papabravo

Joined Feb 24, 2006
21,305
Won’t work. That resistor is wirewound and inductive. Not suitable for RF.
IMHO, the best way to do it is with several larger resistances in parallel so that each resistor can dissipate a portion of the 100W. You can use Manhattan style construction on an FR4 epoxy glass board with copper on one side and mount it inside a paint can with an RF connector of your choice.

4 x 200 Ω of these would work pretty well

https://riedon.com/media/pdf/PF2200.pdf
 

Ian0

Joined Aug 7, 2020
10,269
I made an audio dummy load by soldering a large number of 1206 resistors to a piece of aluminium-substrate pcb.
That might work for RF, or there might be too much capacitance to the substrate.
 

Janis59

Joined Aug 21, 2017
1,863
Once I had to use the 2 kW 50 Ohm dummy load. I obtained the due count of larger non-inductive resistors and soldered between two plates body to body in chess like, if memory tells right 30x40 pieces parallel. As the thermal photography shown bit overheating for inside mounted, I set the line of micro fans thought 40x40 or 50x50 mm. Later it served well for the years to set the air pressure ICP plasma ignition generators.
 

ronsimpson

Joined Oct 7, 2019
3,204
Won’t work. That resistor is wirewound and inductive. Not suitable for RF.
Look up the data sheet. Digikey has "non inductive resistors" that look just like that.

I have used gold non inductive resistors like that in less than 100W and put them in a gallon of mineral oil. That pulls out the heat.

I use resistors in TO-220 and TO-247 packages that are good at RF. What frequency?
Can not find the data sheet now. to-220 This is close but I use the fully insulated version.

Found it. allied

In my HAM days we built 1000w loads like this.
1675262368439.png
 
Last edited:
Top