hello, I've decided to build another F-5 and use the much debated HeatsinkUSA 10.08 inch extrusion, several here thought it was enough, albeit borderline. Euvl states in one of his posts on the topic that it should be good if Kerafols are used. I have obtained a supply of those pads, and thought I'd do a build. I feel they will be fine, no doubt a little warmer than my F-5 using M&M metals larger extrusion.
Now my question is, If the sink does prove to be a little short, would it still be sufficient for a Mini Aleph build? I have the boards and parts to do one of those as well. I thought if marginal, I could use them for a Mini Aleph. Then it occurred to me that I dont know what a Mini Aleph needs to dissipate.
A search found a post from Vdi-nenna who said he used 150 x 430x 50, which should be roughly 6 inches x 17 x 2, somewhat larger than the 10.08 by 8 inches by 2.3 inches of the heatsinkusa. From this it looks as though Mini Aleph may make as much or more heat then F-5?
Thanks for any input,
Russellc
Now my question is, If the sink does prove to be a little short, would it still be sufficient for a Mini Aleph build? I have the boards and parts to do one of those as well. I thought if marginal, I could use them for a Mini Aleph. Then it occurred to me that I dont know what a Mini Aleph needs to dissipate.
A search found a post from Vdi-nenna who said he used 150 x 430x 50, which should be roughly 6 inches x 17 x 2, somewhat larger than the 10.08 by 8 inches by 2.3 inches of the heatsinkusa. From this it looks as though Mini Aleph may make as much or more heat then F-5?
Thanks for any input,
Russellc
I have case that was built with 6" wide and 10" long heat sinks running front to back, with the fins sticking out horizontally, "the wrong way". It dissipates enough heat for my F5. I had mini aleph boards in the same chassis prior to making the F5 boards, and it was enough heat sink for that as well.
I got he sinks from Russ Boss -- I think he is heatsinks USA now.
JJ
I got he sinks from Russ Boss -- I think he is heatsinks USA now.
JJ
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i believe the only people that said it would be borderline were people that hadn't even used them , but were just speculating .
i'm using 7" high slices and biasing higher than normal at over 1.4 a and they never get hotter than 40 c . i believe it was flg that was playing with some and he said that a 5" high pair should be enough for a stock f5 .
cheers Woody
I suspected as much, especially with these 8 inch pieces and kerafols. I've had more than one member tell me they worked fine. I also intend to use them for a Mini aleph build as well.
Russellc
Well, there is a always a possibility the aluminum is not getting hot because the heat is not getting transferred from the output device to the heat sink.
On a more serious note, does the paint stick to the aluminum pretty well. Does it scratch easily or did you have to use some exotic primer?
The paint sticks pretty good if you clean the sinks well, but it's not very durable. Easy to touch up though.
Good point about the heat transfer. That's the one area in these builds where it pays to be a little anal, especially if you're pushing it. I generally work the area down flat with a fine mill file before I do any polishing.
Good point about the heat transfer. That's the one area in these builds where it pays to be a little anal, especially if you're pushing it. I generally work the area down flat with a fine mill file before I do any polishing.
I'm using some of 10.080" heatsinkusa material at 6" in height, it seems to work decently. I attached a thermocouple to it earlier and kept an eye and it seems to have stabilized so snapped a quick picture. Oh and the reading is in C, it's little hard to see since I used my wonderful camera/phone to take the photo.
An externally hosted image should be here but it was not working when we last tested it.
)
I know this may seem like heresy, but I really like Mica and goop vs. pads. I used pads on my first builds then switched (recommended by a friend) to mica.
I don't have the HeatsinkUSA sinks, but they seem more than adequate.
Its a shame this Liquid Pro stuff eats aluminium heatsinks
An externally hosted image should be here but it was not working when we last tested it.
I was going to use mica and goop, and obtained a bunch of mica insulators off Ebay. After reading the thread "Mica and Goop" I learned about the Kerafols. Looks and feels sort of like a silpad, but as the aforementioned thread states, the Kerafols are even better at transmission of the heat to the sink than mica and goop. The heatsink USA 10.080 extrusion has been used sucessfully by several members for both F-5 and MiniAleph, and they have communicated this to me.
Knowing the temp of my other F-5, with a 12 inch wide extrusion I anticipated that the Heatsink USA part would be closer to marginal. Euvl showed some sims that indicate it is sufficient, and thought that the use of the Kerafols would definately place it in the "safe" zone. I'm sure the mica and goop would be fine to, (the same article showing it to surpass silpads)
but I've got the Kerafols, so I'll use them this time. I do like old school, and mica and goop has been around a long time, still one of the best!
Russellc
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Just came across this thread, which is perfect timing. I just ordered a set of the 10" sinks in 8" lengths from HeatsinkUSA yesterday to do Aleph J. I calculated a thermal resistance after derating it by 25% of about .1000 to handle 200W. That gave me a target of two lengths of 10" but figure that by finishing them I can improve their C/W enough to get by. With a 10" length figured the chassis would look too boxy. I read somewhere that several members had great success using ceramic manifold paint on sinks.
Dan
BTW, does anyone know the difference between the IRFP240-ND
Dan
BTW, does anyone know the difference between the IRFP240-ND
An externally hosted image should be here but it was not working when we last tested it.
and the IRFP240PBF-ND? they appear to have identical specs.
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