[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Re: FT-847 Fan noise

At 06:49 PM 4/24/98 -0500, Dan James wrote:
>The information below is forwarded from the WSVHF reflector.
>I don't have an 847, nor can I claim the 'fix' described here works... 
>however, I would like to thank Dave, K4TO for the information. Because of 
>the number of 847's that are showing up on the satellites, and because that 
>radio is of prime interest on this reflector, I've repeated the message 
>  --73 Dan NN0DJ--
>From: 	Dave Sublette[SMTP:k4to@meginc.com]
>Sent: 	Thursday, April 23, 1998 9:45 PM
>To: 	VHF Reflector; W6YX VHF reflector
>Subject: 	[WSVHF] FT-847 Fan noise
>A common complaint about the FT-847 is that the fan noise is irritating
>(and it is).  I have been able to quiet the whine using the following
>Cut a 3" x 3" piece of soft packing foam that is about 2" thick. Be sure
>to use the "open cell" type of foam.  You can tell that it is open cell
>type construction by holding it up to your mouth and blowing air through
>it. Wedge the piece of foam between the four coax connectors so that it
>covers the intake area for the fan.  The whine will then disappear.  The
>foam has little effect on the cooling of the radio.  I think it works
>because the foam causes turbulence in the air flow, disrupting the
>formation of the sound of the whine, which is probably generated by the
>tips of the fan blades.  It may even slow the fan a bit, which stops the
>noise.  However it works, it works.  I can't even see it when it is in
>place. It should also have an added bonus in that it will filter dust
>from the air before it enters the radio.
>Hope this works for you.
>Dave, K4TO

Hi Dave and the rest of the group.

You need to be careful of what type of foam that you use. What you are
doing is slowing the fan down by adding the foam over the fan. If the radio
needs as much cooling as the fan puts out and you slow down the air flow
the radio will run hotter. What I would recommend to do is use a regular
piece of filter media used on a/c units as that will not restrict too much
air. If you want to see how much air that the piece of foam adds, go to
your a/c unit while the fan is running and open the filter grill and just
give the filter a little pull and you can see how much air that you are
restricting. This all adds up to reduced cooling. 
I use muffin fans on my repeaters to force cooling into the cabinet to keep
things cool. The one that I'm building now I had one fan added to the
bottom of the case. This pushed enough air that I could feel the air coming
out of the top with no problem. When I added the filter media the air flow
was reduced so much that I had to add another fan to replace the air that
was lost by the addition of the filter media.

The bottom line is be VERY careful when putting something over the fan's on
your radios...You might not like the results!!!!

73, Bill N4XEO
e-mail: stonehvn@gate.net
home page: http://www.qsl.net/n4xeo
F.A.D.C.A.: http://www.flnet.com/~crosby/fadca