I bought 10 x 250w today, it will be overkill, but it will take anything I'll be throwing at it.

Tall heatsink with a blower on either end should be grand.

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sinus trouble wrote:

Dummy05.png

What's the secondary on the lid with the red?

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The resistors alone in free air can handle 50-60 Watts.

The Dummy will be oil filled and could probably handle a couple of hundred watt for a short duration?

The setup is easily tailored to your own preference? Just a matter of the resistive devices and oil container you need?

alfaeire wrote: ↑Thu Apr 01, 2021 11:51 pm I bought 10 x 250w today, it will be overkill, but it will take anything I'll be throwing at it.

Tall heatsink with a blower on either end should be grand.

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How are you going to make the load 50 ohms with ten terminations?

alfaeire wrote: ↑Thu Apr 01, 2021 11:53 pm

sinus trouble wrote:Dummy05.png

What's the secondary on the lid with the red?

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That extra terminal is a feed through capacitor which i plan to use in sampling the RF voltage to get an idea of power? I may change it to a BNC later to connect to an oscilloscope?

Bton-FM wrote:

alfaeire wrote: ↑Thu Apr 01, 2021 11:51 pm I bought 10 x 250w today, it will be overkill, but it will take anything I'll be throwing at it.

Tall heatsink with a blower on either end should be grand.

Sent from my SM-A526B using Tapatalk

How are you going to make the load 50 ohms with ten terminations?

See nrgkits.nz post above.

"Combine them in parallel and series to get 50R and increase the power rating"

Im not sure if I'll use the 10.
Nrgkitz used 8 in his post above.

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alfaeire wrote: ↑Thu Apr 01, 2021 11:51 pm I bought 10 x 250w today, it will be overkill, but it will take anything I'll be throwing at it.

Tall heatsink with a blower on either end should be grand.

Sent from my SM-A526B using Tapatalk

Yes they will work exactly the same as the resistors in mine!

You will have to carefully plan the layout and best way to Parallel/Series the connections

As B-Ton mentioned

sinus trouble wrote:

alfaeire wrote: ↑Thu Apr 01, 2021 11:51 pm I bought 10 x 250w today, it will be overkill, but it will take anything I'll be throwing at it.

Tall heatsink with a blower on either end should be grand.

Sent from my SM-A526B using Tapatalk

Yes they will work exactly the same as the resistors in mine!

You will have to carefully plan the layout and best way to Parallel/Series the connections

As B-Ton mentioned

Ahh I just realised these are different to the ones posted above by Nrgkits

His have 2 tabs, mine only a single.

alfaeire wrote: ↑Fri Apr 02, 2021 12:07 am

Bton-FM wrote:

alfaeire wrote: ↑Thu Apr 01, 2021 11:51 pm I bought 10 x 250w today, it will be overkill, but it will take anything I'll be throwing at it.

Tall heatsink with a blower on either end should be grand.

Sent from my SM-A526B using Tapatalk

How are you going to make the load 50 ohms with ten terminations?

See nrgkits.nz post above.

"Combine them in parallel and series to get 50R and increase the power rating"

Im not sure if I'll use the 10.
Nrgkitz used 8 in his post above.

Sent from my SM-A526B using Tapatalk

NRGkitz has done it with 100 Ohm resistors and they are the leaded type so it makes combining several a lot easier than with terminations. It means you don't have to use the heatsink as ground.

Now I've seen Sinus' post, I see how you are going mount them.

I made my load in a similar fashion as NRGkits has done, but with two 250W resistors rather than eight on a big heatsink.

alfaeire wrote: ↑Fri Apr 02, 2021 12:21 am

sinus trouble wrote:

alfaeire wrote: ↑Thu Apr 01, 2021 11:51 pm I bought 10 x 250w today, it will be overkill, but it will take anything I'll be throwing at it.

Tall heatsink with a blower on either end should be grand.

Sent from my SM-A526B using Tapatalk

Yes they will work exactly the same as the resistors in mine!

You will have to carefully plan the layout and best way to Parallel/Series the connections

As B-Ton mentioned

Ahh I just realised these are different to the ones posted above by Nrgkits

His have 2 tabs, mine only a single.

That’s what I was getting at!

alfaeire wrote: ↑Fri Apr 02, 2021 12:21 am

sinus trouble wrote:

alfaeire wrote: ↑Thu Apr 01, 2021 11:51 pm I bought 10 x 250w today, it will be overkill, but it will take anything I'll be throwing at it.

Tall heatsink with a blower on either end should be grand.

Sent from my SM-A526B using Tapatalk

Yes they will work exactly the same as the resistors in mine!

You will have to carefully plan the layout and best way to Parallel/Series the connections

As B-Ton mentioned

Ahh I just realised these are different to the ones posted above by Nrgkits

His have 2 tabs, mine only a single.

Yes not ideal? But still possible? You could use two or four isolated ground points? (Plates or heatsinks) it depends on how creative you wanna get on the design?

As an example? You could mount two resistors in parallel on one heatsink (25Ohm) and two on another heatsink? Once connected in series would give you the 50Ohm you require!

Mount the two heatsinks on an insulated base! Sorted!

sinus trouble wrote:

alfaeire wrote: ↑Fri Apr 02, 2021 12:21 am

sinus trouble wrote:
Yes they will work exactly the same as the resistors in mine!

You will have to carefully plan the layout and best way to Parallel/Series the connections

As B-Ton mentioned

Ahh I just realised these are different to the ones posted above by Nrgkits

His have 2 tabs, mine only a single.

Yes not ideal? But still possible? You could use two or four isolated ground points? (Plates or heatsinks) it depends on how creative you wanna get on the design?

Obviously not to scale. But something like that?

EDIT : I totally misread the ohms on the discription, so the design definitely wouldn't work.

sinus trouble wrote:As an example? You could mount two resistors in parallel on one heatsink (25Ohm) and two on another heatsink? Once connected in series would give you the 50Ohm you require!

Mount the two heatsinks on an insulated base! Sorted!

I'm confusing myself here over something so simple.. I need sleep

These are the ones I ordered, 250w 50Ohm
https://a.aliexpress.com/_mMJLi8F

So, if the resistors are 50ohm, it remains 50ohm in the design does it not?

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sinus trouble wrote: ↑Thu Apr 01, 2021 11:45 pm Dummy03.png

Very nice Sinus. I like the build quality

No! Resistors in parallel will reduce in Ohmic value but double in power (Watts)

Resistor in series will increase in Ohmic value but will remain the equivalent of one resistor in terms of power.

Haha! Get some Kip and worry about it another day!