Jon,
That horizontal vs. vertical fins only applied to when the heat sink is
mounted on the back panel or sides of a box. Doesn't apply when it is top
mounted (of course).
This was one of the complaints of the Ten-Tec transceivers. They always had
horizontal fins on the back. Probably better facilitated mounting the
transistors. (I guess).
73 - Rick, DJ0IP
(Nr. Frankfurt am Main)
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of k6jek
Sent: Friday, March 07, 2014 12:42 AM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] Noise from Fans
Nicely done.
Not on Ten-Tec but on other gear I've built temperature controllers. Most of
the time the fans run at a snail's pace and make essentially zero noise.
They only pick up the pace when they need to. Some ham offers a nice little
kit but I can't seem to find the contact information.
Incidentally, a friend who does thermal analysis as part of his engineering
practice pointed out that horizontal fins on heat sinks work poorly without
a fan. He threw out some numbers but I've forgotten them. I seem to recall
quite a difference between horizontal and vertical fins with the same
surface area. This was after I built a home brew AM transmitter with giant,
horizontally-finned heat sinks for the MOSFETs. I do remember him saying it
takes very little air from a fan to dramatically improve the situation. So
that's what added, just a little bit of moving air.
Jon
On Mar 6, 2014, at 3:02 PM, K8JHR wrote:
> Here is my solution - using very quiet computer fans. See the link at the
bottom of the page: "Cooling Fan Project"
>
> http://k8jhr.com/project_links.html
>
> I sometimes use a small resistor to slow them down, but they run on 12v
and usually spec out around 15-19 dB noise factor.
>
> I just could not spend over $40 on the TT fan, when I could make one for
less than $10 - including buying a brand new fan. Mine are CoolerMaster
fans that cost me $7 I think.
>
> Maybe my plan will spur some other ideas.
>
> ------------------------- K8JHR ---------------------
>
>
> On 3/6/2014 5:21 AM, Rick - DJ0IP / NJ0IP wrote:
>
>> At the time, most small PC towers had small case fans that ran on 12v,
>
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