[RFI] Nutone intercom problem

Ed - K0iL Ed - K0iL <k0il@arrl.net>
Sat, 6 Jan 2001 23:12:09 -0600

Tim,  (that isn't the "Tool-Man Taylor" is it? Bet you get that alot. 
 Sorry :^)

I think your neighbor needs to call up Nutone and have a talk with them 
about their defective product.  For them to say they cannot help is 
unbelievable!  They designed the thing.  They should be able to resolve 
defects in it.  Period!

I would strongly suggest to your neighbor to call the manufacturer and put 
the fault squarely on their design and lack of filtering, and then demand a 
resolution.  He could explain that this problem is being discussed on a 
nationwide internet discussion group, and we are all waiting to hear what 
they have to say about their design and product.  This is the kind of 
pressure that needs to be exerted on these manufacturer's to get them to 
change.  They need to know their name is being dragged through the mud 
unless they come up with a better response then they can't help.  That's 
Barbara Streisand!  They have an engineer somewhere who can help, or else 
they shouldn't be selling any products.

Now to your question.  I imagine you're on good terms with your neighbor or 
else you wouldn't be so willing to help him.  But, I would not do any EMI 
filter work yourself without assessing the risks.  I would be willing to 
show him what needs to be installed and how to install it, but anything 
beyond that opens up a liability.  If you're best friends, you may feel 
comfortable helping out a little more.

As for who can do the work, it depends on your state laws.  It may require 
a licensed electrician or service technician.  It may depend on Nutone's 
resolution assuming they come up with one.  I don't recommend the use of 
capacitors as that may cause damage to newer solid state amps.

Ferrites are the best choice and should cure the problem if it's mainly 
audio rectification via common mode pick-up (I assume).  There are 
instructions that come with the Radio Shack ferrites that show how they 
should be installed.  You could give them as a gift to your neighbor and 
show him how to install them.  Then let him do the installation.

Be a good neighbor but be cautious.

de ed -K0iL
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           Ed Edwards    --    K0iL
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On Saturday, 06 January, 2001 1:59 PM, Tim Taylor 
[SMTP:tim-taylor@home.com] wrote:
> My neighbor has an extensive IM 4006 Nutone music/intercom.  I believe he 
has a complement of at least 18 speakers throughout the house.  Well 
needless to say, after I put up my tower, I can be copied quite loud on his 
intercom.  This is true for all frequencies from 80 - 10 at power levels of 
100 watts and up.  I've called the local Nutone dealers but they can't 
provide any help.
> It appears as though the speakers are connected to a main unit through 6 
conductor ribbon cable. The inside of the 'rough out" is quite crowded with 
little room to work.
> As is true of any RFI case, I hesitate to go inside the unit to apply 
caps or ferrite.  Who could I turn to that could perform the work?
> Anyone authorized dealers want a free trip to Florida?
> Thanks for any help/advice.
> -Tim
>  << File: ATT00000.htm >>


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