Topics

Cooling fan Shroud

_Dave_ K0MBT
 

Decided to put a cooling fan on my ubitx v4. A friend gave me a couple of squirrel cage fans.
On my other rigs I have gone with conventional fans. One of those was getting noisy and decided to replace it with my new fans.

I had to make a shroud to move the air onto the heatsinks. The fan is bolted to the back of the Indian case. It looks like they put in a port for a small conventional fan but that isn't what I have.

The print file and the fan used was here:
https://www.thingiverse.com/thing:3360539

Maybe someone will find it helpful. This forum is where I find many solutions to bitx radio issues.

Albert Peter
 

I also looked for a fan solution on my uBITX.  I tried several salvaged from computer parts, but all were too noisy  I finally came up with this one:

Noctua NF-A4x20 PWM Premium-Quality Quiet 40mm Fan – $14.99 from Amazon. 

A bit pricey, but it has virtually no acoustic noise and very little, if any electrical noise.  Mounted on the side of my case and now everything is cool as can be.

Al

AC8GY

 

 

Jim Sheldon
 

I originally used a 4" fan I got off an old computer power supply on the back of that same style case - electrically and acoustically VERY noisy.  Asked Al yesterday about his little fan and ordered one.  It will be here Friday.  Now I have to find another case like that one so I can do a scratch JackAL/uBITX build with the 5" display.  

Jim - W0EB

------ Original Message ------
From: "Albert Peter" <albertfpeter@...>
To: "BITX20@groups.io" <BITX20@groups.io>
Sent: 1/17/2019 8:43:13 AM
Subject: Re: [BITX20] Cooling fan Shroud

I also looked for a fan solution on my uBITX.  I tried several salvaged from computer parts, but all were too noisy  I finally came up with this one:

Noctua NF-A4x20 PWM Premium-Quality Quiet 40mm Fan – $14.99 from Amazon. 

A bit pricey, but it has virtually no acoustic noise and very little, if any electrical noise.  Mounted on the side of my case and now everything is cool as can be.

Al

AC8GY

 

 

Bob Lunsford <nocrud222@...>
 

Try a 2W resister in series with some conventional fans and
the noise is much less. Run it a while and check to see that
the fan is not getting too warm. The resistor value may be in
the 500-1000 ohm range. That's where I would start, anyway.

It's nice to have a few fans of various sizes on hand. They
are sometimes seen at hamfests. Most cost between $1 and
$5 which is not all that much to pay for a small fan. I have
also rescued some from computer-type power supplies and
depending on size of power supply, I have some that range
between 2-in and 4-in. Most are designed to run for years.

Bob — KK5R

--------------------------------------------

On Thu, 1/17/19, Jim Sheldon <@W0EB> wrote:

Subject: Re: [BITX20] Cooling fan Shroud
To: BITX20@groups.io
Date: Thursday, January 17, 2019, 10:02 AM

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originally used a 4" fan I got off an old computer
power supply on the back of that same style case -
electrically and acoustically VERY noisy.  Asked Al
yesterday about his little fan and ordered one.  It will be
here Friday.  Now I have to find another case like that one
so I can do a scratch JackAL/uBITX build with the 5"
display.  
Jim -
W0EB


------ Original Message ------
From: "Albert Peter" <albertfpeter@...>
To: "BITX20@groups.io" <BITX20@groups.io>
Sent: 1/17/2019 8:43:13 AM
Subject: Re: [BITX20] Cooling fan Shroud


I also looked for a fan
solution on my uBITX.  I tried several salvaged from
computer parts, but all were too noisy  I finally came up
with this one:Noctua NF-A4x20 PWM Premium-Quality
Quiet 40mm Fan – $14.99 from Amazon.  A bit pricey, but it has virtually
no acoustic noise and very little, if any electrical
noise.  Mounted on the side of my case and now everything
is cool as can be.AlAC8GY

Woody
 

Fan controllers are easy to build and minimize noise when not needed.
Something like these...  YMMV

Variable analog - Had to add the 3.3 ohm to reduce induced noise in the uBITx from high current fan.

OR

Switched - OFF/ON



Inexpensive fans can be had surplus, like at:
https://www.allelectronics.com/category/220/fans/1.html
https://www.mpja.com/DC-Axial-Fans/products/48/


Albert Peter
 

The only problem with fan speed controllers is a reduction in cooling capability.  IMHO it is better to start with a capable quiet fan that does not require more circuitry.  It may cost a bit more, but is a simpler solution.

Al

AC8GY

 

Sent from Mail for Windows 10

 

From: Woody
Sent: Thursday, January 17, 2019 11:57 AM
To: BITX20@groups.io
Subject: Re: [BITX20] Cooling fan Shroud

 

Fan controllers are easy to build and minimize noise when not needed.

Something like these...  YMMV

Variable analog - Had to add the 3.3 ohm to reduce induced noise in the uBITx from high current fan.

OR

Switched - OFF/ON



Inexpensive fans can be had surplus, like at:
https://www.allelectronics.com/category/220/fans/1.html
https://www.mpja.com/DC-Axial-Fans/products/48/

 

Woody
 

Not sure why a reduction in cooling capacity with controllers.  Certainly is reduced when not needed. That is the intent.  The temperature proportional analog version could possibly result in less than max CFM, but not much if set up properly.  There is no reduction in CFM with the switched version.  the down side to that is that, when on, it is running at max capacity and more noisy.
Woody - KZ4AK

Doug W
 

On Thu, Jan 17, 2019 at 11:18 AM, Albert Peter wrote:
IMHO it is better to start with a capable quiet fan that does not require more circuitry.  It may cost a bit more, but is a simpler solution.
I totally agree with Al.  I have this fan https://www.digikey.com/product-detail/en/sunon-fans/HA60251V4-1000U-A99/259-1793-ND/ running arm's length away from me in a µBITX in an EF-01 enclosure on my desk.  It is so quiet I sometimes have to check that it is still working.
 
--
www.bitxmap.com

Evan Hand
 

I believe the point that Albert is making that it is better to have a quite fan that meets all of the requirements without any extra circuitry that can fail.  I would agree that if a noisy fan is the only choice, then putting in a controller to minimize the noise while still removing the heat is the next best solution.  If properly designed, installed, and tuned, then there would not be a change in the amount of heat that can be removed as the heat sinks get hotter.  I would caution that response time can get in the way of keeping cool quick enough to not cause an issue.  An always on at max fan does not have this issue.

My opinion, use as you see fit.

73
Evan
AC9TU

Tom, wb6b
 

Another easy solution is to simply run the fan from the 12V transmit power, assuming that is not what you are already doing. No reason to run the fan while receiving.

Tom, wb6b

Bob Lunsford <nocrud222@...>
 

The power to the transmit wire is always connected so
there would have to be a relay to only apply power to
the relay when the PTT line is enabled. More complexity.


There are many schemes to make work what you suggest
which is essentially a good idea. Big rigs do this. Would
need a relay and a relay driver that is connected to the
PTT line. As the old saying goes, "It's doable."

On the other hand, drawing air out of a rig's box is the
best way since it is removing the hot air. But if the fan
is placed so air is forced into the box at the bottom, the
placement of the fan reduces the sound of the fan if the
box is elevated on feet, for example. In other words,
placement of the fan is an essential element in the noise
produced. Also, if the fan is mounted on rubber bushings,
the sound is not transmitted mechanically back into the
box. If the box is a hunk of iron, no problem but most of
them are small and light which invites some coupling
of the vibrations back into the box and makes the box
a soundboard for the noise. However, most sound is
acoustic and with mine, all I heard was wind noise and
this is why merely slowing down the fan is a way to
eliminate a lot of the sound. The exhausted air does
not need to be very high so slowing it down does what
is needed: Removing the hot air from the box. The
proper value of resistor is therefore a way to do this
and it's now something new or unique. Also, the fan
I used is essentially like the one suggested previously
only slightly larger. It was a 2-in fan measuring from
side to side.

Bob — KK5R

--------------------------------------------

On Thu, 1/17/19, Tom, wb6b <wb6b@...> wrote:

Subject: Re: [BITX20] Cooling fan Shroud
To: BITX20@groups.io
Date: Thursday, January 17, 2019, 9:02 PM

Another easy solution is
to simply run the fan from the 12V transmit power, assuming
that is not what you are already doing. No reason to run the
fan while receiving.

Tom,
wb6b

_Dave_ K0MBT
 

I choose to run the fan full time. The reason I run the fan while receiving is that it pulls heat out of the small heat sinks.

On my original ubitx, I run the finals at 20 volts and use it for digital. The heatsinks that I use on that radio weigh about 4x as much with a lot more finning. The fan is a regular 3" computer fan with a snug fitting shroud. I can run the transmitter at 20 watts into a dummy load in cw mode for an indefinite amount of time without making the transistors hot.

This set up is not as effective but it pull heat out of the heatsinks. I may well use larger heatsinks and design a different fan shroud.

Not planning on running a temp controlled fan nor just run it whilst the tx is on.

Tom, wb6b
 

Very good. By the way, I do like your shroud and I appreciate your putting it up on Thingiverse.

Tom, wb6b