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Author Topic: FT-847 Noisey Fan  (Read 285 times)
EI6IL
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Posts: 21




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« on: February 12, 2008, 03:17:50 PM »

Hi Folks,
Just wondered if anyone knows the best modification to use to either quieten or eradicate the extremely noisey cooling fans on the FT-847.

Picked up a used FT-847 and the noise is like thunder.

Saw a number of mods on the net from the addition of a Thermostatic Fan Speed Controller circuit/ Fan replacement /zener diode in series with the power lead / ganging the rear fan with the circuitry that controls the internal fan/disconnecting the rear fan !! and someone else suggests muffling the fan with some foam !!

Any ideas are welcome please.

Thanks,
Don EI6IL  
 
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K0BG
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Posts: 9896


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« Reply #1 on: February 12, 2008, 04:18:27 PM »

Unless the bearings are bad, what you have is what you have.

Small radios generate heat in a small space, and that space has to be kept cool (within reason). Obviously, this requires a fan. Yes, in an inclosed area (base station rather than a mobile) they can be noisy, but the alternative is, something gets too hot and fails as a result.

Alan, KØBG
www.k0bg.com
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KC8VWM
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Posts: 3121




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« Reply #2 on: February 12, 2008, 04:22:59 PM »

You could choose a more directional or noise cancelling microphone.

You could move the equipment away from your operating position.

Sometimes the fan sound is being reflected or further enhanced off hard surfaces located in the vicinity behind the radio. You could dampen the reflected acoustics using absorbing materials placed on the wall behind the radio as long as you do not impede air flow.

Doing any "mod" to the fan itself will compromise the ability of the equipment to cool itself peoperly and in my estimation should never be attempted.

73 de Charles - KC8VWM
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WA3SKN
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Posts: 5554




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« Reply #3 on: February 13, 2008, 04:31:16 AM »

If the bearings are shot, replace with the same type fan.  If you are talking about normal fan noise, I would hesitate trying to change the cooling arrangement... the engineers put a lot of planning into proper cooling of their radios, proper air circulation is important.

-Mike.
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W3LK
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Posts: 5639




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« Reply #4 on: February 13, 2008, 07:33:59 AM »

If the noise from the fan is picked up by the microphone, then either something is wrong with the fan, probably bad bearings, or you have the mike gain turned up too high and you are trying to talk from a couple of feet away from the mike.

Not even the loud fan on my old AL-80A amp is picked up by my mike. Then again, I use a headset with a boom mike one inch from my mouth.

73,

Lon - W3LK
Naugatuck, Connecticut
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A smoking section in a restaurant makes as much sense as a peeing section in a swimming pool.
EI6IL
Member

Posts: 21




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« Reply #5 on: February 17, 2008, 10:28:01 AM »

Hi Folks,
    Thank you for the replies and information,I replaced the fan but still as noisey so I have decided to leave well enough alone and let it be.
The radio has two fans on all the time, one is an inner fan and one external at the rear which is where all the racket comes from. The noise isnt been picked up by my microphone which I seldom use anyway.
Not too worry thanks again.

Best 73's,
Don EI6IL
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