> -----Original Message-----
> From: Mike King
> I just got done pounding out the ARRL June VHF Contest over the weekend.
> I
> have few folks next door with baby monitors, they are complaining.
> Telling them that baby monitors are Part 15 FCC devices and that they have
> to accept any interference draws the "deer in the headlight blank stare"
>
It's interesting that the ARRL RFI Book doesn't actually mention
"Baby Monitors" but instead talks about wireless intercom which is what a
baby monitor is only one-way.
If you want to try to "help" your neighbor, remember that since
these are devices "Designed to rcv a radio signal" if it's the 49Mhz type,
you only have the Part 15 exemption to fall back on. If it's caused by
front-end overload, I'm not sure you can make much of a dent to reduce RFI
due to the inherent design flaws; but if it's simply audio rectification,
the ferrite-core route might clean them up. Get some small cores, small
enough to fit inside the Rcvr unit placing them on the speaker wires with as
many turns as possible as close to the circuit board as possible. Also
adding a ferrite choke to the AC line (if it has one) could reduce RFI
entering there. Your neighbor can buy some at Radio Shack but they're
probably too big to fit. Palomar makes many sizes in a RFI-kit package.
Check QST or CQ for their number or web address, or maybe the the Palomar
guys will respond here!
One other thing: Don't "Tell them" what Part 15 says. Show them!
It's in the owner's manual which almost everyone throws away, and it
sometimes actually has the Part 15 warning --"This device MUST accept
interference, and it MUST NOT cause harmful interference..."-- printed on
the units themselves. It may be on the base unit or even on the inside of a
battery cover. But I think it's required to be on the unit somewhere. So
show them what it says ON THEIR UNIT!!! and in the manual if they still
have that as well. They can then argue with the FCC about why it MUST
ACCEPT interference and what that means in their case. Give them the number
1-877-CALL-FCC so they can hear it for themselves.
> So, in order to try to do something else, I have told one fellow to bring
> in
> the book to look at. I want to see if the manufactuer has any tips, etc.
>
That's a good start. Also, be sure to get one of the ARRL's
pamphlets which is written for the person who has a device receiving RFI.
You can download a copy on the ARRL Web at www.arrl.org to give your
neighbor. There is a bunch of RFI info in the ARRL's TIS section.
Good luck Mike!
73,
de ed -K0iL
Omaha, Nebraska
(The other side of the Mo River!)
--
FAQ on WWW: http://www.contesting.com/FAQ/rfi
Submissions: rfi@contesting.com
Administrative requests: rfi-REQUEST@contesting.com
Questions: owner-rfi@contesting.com
|