Dummy load

Everything technical about radio can be discussed here, whether it's transmitting or receiving. Guides, charts, diagrams, etc. are all welcome.
User avatar
sinus trouble
proppa neck!
proppa neck!
Posts: 817
Joined: Fri Aug 22, 2014 11:34 pm

Re: Dummy load

Post by sinus trouble » Thu Apr 01, 2021 11:45 pm

Dummy03.png
You do not have the required permissions to view the files attached to this post.
I am as stupid as I look! :|

User avatar
sinus trouble
proppa neck!
proppa neck!
Posts: 817
Joined: Fri Aug 22, 2014 11:34 pm

Re: Dummy load

Post by sinus trouble » Thu Apr 01, 2021 11:47 pm

Dummy04.png
You do not have the required permissions to view the files attached to this post.
I am as stupid as I look! :|

User avatar
sinus trouble
proppa neck!
proppa neck!
Posts: 817
Joined: Fri Aug 22, 2014 11:34 pm

Re: Dummy load

Post by sinus trouble » Thu Apr 01, 2021 11:48 pm

Dummy05.png
You do not have the required permissions to view the files attached to this post.
I am as stupid as I look! :|

alfaeire
no manz can test innit
no manz can test innit
Posts: 125
Joined: Tue Aug 11, 2015 11:17 am

Re: Dummy load

Post by alfaeire » 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. Image

Sent from my SM-A526B using Tapatalk


alfaeire
no manz can test innit
no manz can test innit
Posts: 125
Joined: Tue Aug 11, 2015 11:17 am

Re: RE: Re: Dummy load

Post by alfaeire » Thu Apr 01, 2021 11:53 pm

sinus trouble wrote:
Dummy05.png
What's the secondary on the lid with the red?

Sent from my SM-A526B using Tapatalk


User avatar
sinus trouble
proppa neck!
proppa neck!
Posts: 817
Joined: Fri Aug 22, 2014 11:34 pm

Re: Dummy load

Post by sinus trouble » Thu Apr 01, 2021 11:57 pm

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?
I am as stupid as I look! :|

User avatar
Bton-FM
tower block dreamin
tower block dreamin
Posts: 444
Joined: Sun Jun 16, 2019 2:55 pm
Location: Beside the seaside

Re: Dummy load

Post by Bton-FM » Fri Apr 02, 2021 12:02 am

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. Image

Sent from my SM-A526B using Tapatalk
How are you going to make the load 50 ohms with ten terminations?

User avatar
sinus trouble
proppa neck!
proppa neck!
Posts: 817
Joined: Fri Aug 22, 2014 11:34 pm

Re: RE: Re: Dummy load

Post by sinus trouble » Fri Apr 02, 2021 12:03 am

alfaeire wrote:
Thu Apr 01, 2021 11:53 pm
sinus trouble wrote:Dummy05.png
What's the secondary on the lid with the red?

Sent from my SM-A526B using Tapatalk
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?
I am as stupid as I look! :|

alfaeire
no manz can test innit
no manz can test innit
Posts: 125
Joined: Tue Aug 11, 2015 11:17 am

Re: RE: Re: Dummy load

Post by alfaeire » 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. Image

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


User avatar
sinus trouble
proppa neck!
proppa neck!
Posts: 817
Joined: Fri Aug 22, 2014 11:34 pm

Re: Dummy load

Post by sinus trouble » Fri Apr 02, 2021 12:08 am

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. Image

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 :)
I am as stupid as I look! :|

alfaeire
no manz can test innit
no manz can test innit
Posts: 125
Joined: Tue Aug 11, 2015 11:17 am

Re: RE: Re: Dummy load

Post by alfaeire » 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. Image

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.


Image

User avatar
Bton-FM
tower block dreamin
tower block dreamin
Posts: 444
Joined: Sun Jun 16, 2019 2:55 pm
Location: Beside the seaside

Re: RE: Re: Dummy load

Post by Bton-FM » Fri Apr 02, 2021 12:28 am

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. Image

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. :tup

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

User avatar
Bton-FM
tower block dreamin
tower block dreamin
Posts: 444
Joined: Sun Jun 16, 2019 2:55 pm
Location: Beside the seaside

Re: RE: Re: Dummy load

Post by Bton-FM » Fri Apr 02, 2021 12:31 am

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. Image

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.


Image
That’s what I was getting at!

User avatar
sinus trouble
proppa neck!
proppa neck!
Posts: 817
Joined: Fri Aug 22, 2014 11:34 pm

Re: RE: Re: Dummy load

Post by sinus trouble » Fri Apr 02, 2021 12:36 am

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. Image

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?
I am as stupid as I look! :|

User avatar
sinus trouble
proppa neck!
proppa neck!
Posts: 817
Joined: Fri Aug 22, 2014 11:34 pm

Re: Dummy load

Post by sinus trouble » Fri Apr 02, 2021 12:51 am

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 am as stupid as I look! :|

alfaeire
no manz can test innit
no manz can test innit
Posts: 125
Joined: Tue Aug 11, 2015 11:17 am

Re: RE: Re: RE: Re: Dummy load

Post by alfaeire » Fri Apr 02, 2021 1:07 am

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? Image

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



alfaeire
no manz can test innit
no manz can test innit
Posts: 125
Joined: Tue Aug 11, 2015 11:17 am

Re: RE: Re: Dummy load

Post by alfaeire » Fri Apr 02, 2021 1:26 am

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?

Sent from my SM-A526B using Tapatalk


User avatar
Zozo
no manz can test innit
no manz can test innit
Posts: 220
Joined: Sun Feb 14, 2021 9:33 am
Location: 3rd rock from the Sun

Re: Dummy load

Post by Zozo » Fri Apr 02, 2021 1:48 am

Series Parallel.png
You do not have the required permissions to view the files attached to this post.
~Give me a transmitter with things that glow any day!

User avatar
Zozo
no manz can test innit
no manz can test innit
Posts: 220
Joined: Sun Feb 14, 2021 9:33 am
Location: 3rd rock from the Sun

Re: Dummy load

Post by Zozo » Fri Apr 02, 2021 1:49 am

sinus trouble wrote:
Thu Apr 01, 2021 11:45 pm
Dummy03.png
Very nice Sinus. I like the build quality :tup
~Give me a transmitter with things that glow any day!

User avatar
sinus trouble
proppa neck!
proppa neck!
Posts: 817
Joined: Fri Aug 22, 2014 11:34 pm

Re: Dummy load

Post by sinus trouble » Fri Apr 02, 2021 1:54 am

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! :lol:
I am as stupid as I look! :|

Post Reply