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Aluminum Clad Wire Wound Resistors???

ElectronTubesRule

Active Member
Sep 6, 2011
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Do these only provide a benefit if mounted to chassis or heat sink? I have never used them before and was going to use them since I have them already in my parts pin. The circuit is being built on perf board or bread board.....So I was wondering if they would provide any real benefit if they do not have a surface to transfer heat too? It is my voltage doubler/rectifier board. I was figuring that since I have them I might as well use them? If I need to I could leave them off the board and mount them to the chassis if it is going to make a big difference.
 

I guess I've never seen one, or at least never seen them described in that way before. I can tell you that heat 'conduction' is more efficient than heat 'induction'. 'Conduction' being the transfer of heat between contacting materials, 'induction' as in that heat being transferred through the air, free space, whatever. That depends on what the materials in contact are though.
Most all circuits of that type as you mentioned are 'open' circuits, usually no heat sink attached. No idea what the answer to your question is, sorry.
- 'Doc
 
My only concern would be the voltage rating of them since you are using them in a high voltage circuit. Obviously they would handle the heat better if mounted on a chassis, that's what they were meant for, however only you will know if that is necessary based on your circuit design and values used.
 
I have never seen them used before.Seeing how they are in an aluminum heat sink type of casing I assumed they where meant to be used on the chassis but my Dad told me not to assume things if their was any way to get the correct answer.

They where in plastic bags with parts I bought NOS from a garage sale. Everything was still in the OEM box's or plastic bags. I had never seen them before in a circuit but they have the ratings I need. The design calls for 10watt 100Ohm and 250hm wire wound resistors.

I am basically using the design from "Easy Kilowatt Amplifier" doubler design. The only real significant change I am making is that the rectifier diodes I have are 6A and 10A 1000V diodes and the plan only calls for 2A 1000V diodes. The cap section calls for I think 6 240uf 450V caps, I only 100uf 450V caps so I am going to use 14 of my 100uf 450V caps that will get me to with in 40uf of the original design. I will use a combo of series and parallel connections so the circuit will still only see 6 caps in relation to voltage multiplication. Since I have 25 of these caps 14 is not much of a sacrifice. They are teflon caps intended for aviation related electronics mostly high power radar systems and digital communication gear.

I would not imagine that the heat will be that bad with this type of circuit. If I leave out ballancing resistors from the diode and cap sections that will further reduce heating!I am going to have plenty of axial flow fans inside the case moving air for each section. Each section will be divided from the rest. So the heat from the tubes will not be mixing with the rest of the case, the power supply if I out it in the case will like wise have it's own divided area and it's own air flow. Combinations or axial flow fans like Heath Kit used and muffin fans will be used to keep things cool.

Thank You though because to be honest I figured they where best used mounted to a chassis or additional heat sink!But now instead of an assumption I know it to be fact. I donot have to use them I can save them and use more conventional wire wound resistors. Resistors are cheap!
 
They look like this right? The power rating assumes they are mounted on an appropriate heat sink but will handle about 1/10 that in open air without a heat sink. Matbe a tad more.

2Q==
images

2Q==
 
Ah ha! Now I know what you were talking about. Oh well, I haven't thought of those things in years, and can't ever remember using one.
- 'Doc
 
Yep look like that. I will prop. save them then and use them when I need them and have a high heat environment. I plan on using some fans in the power supply area and venting so heat should not be much of an issue.
 

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