F2 running hot(how hot is hot?)

[Aron]

Hi,
i just got my hands on a F2 clone. It gets very hot, mutch hotter than my old A-40(mutch bigger sinks). I can put my hand on the top-plate for maybe 20 seconds before it gets too hot.
Is this too hot?
I tried to search the forum but did not find an answer that cooled me down.
Where should i measure the heat and what temperature is "safe"
I am a newbie in ss classA.
Thanks
Aron

 

[Zen Mod]

Hi,
i just got my hands on a F2 clone. It gets very hot, mutch hotter than my old A-40(mutch bigger sinks). I can put my hand on the top-plate for maybe 20 seconds before it gets too hot.
Is this too hot?
I tried to search the forum but did not find an answer that cooled me down.
Where should i measure the heat and what temperature is "safe"
I am a newbie in ss classA.
Thanks
Aron

Papa use to say - skin is your best meter

if you can rest your palm on hsink for 5 secs , everything is OK ;

then temp is around 50-55C

 

[Gyuri]

Yes, and what the situation if somebody is a fakir, than I?
This method does not work reliably in this case.
Gyuri

 

[hifimaker]

The test Zen Mod mentions works well. I also have a friends perform the same test when they came over to listen. Group consensus is the shortest duration was 6 seconds and the longest was 12 seconds after 2 hours of use. Averaging nearly a dozen "hand tests" came to 7 seconds.

Over three years and my A30 is still running strong.

-David

 

[Tea-Bag]

lets see a pic of the sinks.

this sucker produces a lot of heat. I use 2 12" X 6" per channel. One sink per FET. The power resistors inside can roast a small cornish hen.

If it runs a little too hot, you may be able to put some CPU sinks on the inside and bond them (permanenty) using thermal epoxy.

 

[hifimaker]

If you can place your hand on the top of the heat sink after 1 hour, then 2, then 3 hours and you and your friends can touch it for more than 5 seconds - you should be within range.

As Tea-Bag suggested, post a picture of the heat sink if you still have questions.

BTW, I believe these power mosfets need to run hot to perform best. It is possible to over heat sink as well.

-David

 

[Aron]

Re: Re: F2 running hot(how hot is hot?)

Papa use to say - skin is your best meter

if you can rest your palm on hsink for 5 secs , everything is OK ;

then temp is around 50-55C

Hi!
I removed my hands after 10sec and could hold it longer. I am a chef and are used to burning my hands. I guess the amp is in the safe zone. I´ll roast a friend and see how long he can hold it. Will post back with pictures if it fails the test.
Thanks everyone responding to my question.
Aron

 

[twitchie]

My F2 measures 53C and it feels hot enough that you really don't want to keep your hand on it longer than 2 or 3 seconds , but you don't want to look like a wimp, so you hang on for about 5 and cry about it when nobody's looking

but it's those 1 ohm resistors you really need to stay away from - I measured those as high as 83C

who would be foolish enough to stick their hands in a running amp you say? Why the fool who needs to adjust it after it warms up, that's who

 

[Babowana]

Don't you remember this?

 

[Scribble]

I find its good to measure the packages them selves to see if they are about the same. On a channel of my Aleph 30 i had one device which was not torqued down enough and was running HOT HOT. Only picked it up with an infra-red thermometer. A quick nip up and it was running within a few degree's of the others.

 

[steenoe]

Caution!
The F2's extraordinary heat is partly caused by Q1's source resistors. They run really hot, and doesnt influence the heatsink temp. that much!! A well ventilated enclosure, is highly recommendable. Depending on the particular build, you might want to drill a few holes in the top/bottom plates. ( Yep, I build one )