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Re: [Amps] RF Interference

To: "Bob Maser" <>, "AMPS" <>
Subject: Re: [Amps] RF Interference
From: "Paul Kraemer" <>
Date: Sat, 11 Oct 2008 11:23:48 -0500
List-post: <">>
Most of this consumer "crap" was never designed with thoughts of rfi.
If it passes the emission standards (if any) for them it is good to go
At least being a ham the stuff I design for my customers is tested for 
performance in presence of rf and other power line noise.
I would try 0.01mfd disc ceramics across the pushbutton leads and maybe one 
from each side to ground or common on the circuit board. Also, make sure 
there is same across dc power to micro chip(s) do this right at the chip 
with short leads.
Good luck! How a micro responds to interference can be very tricky and 
difficult to tame. It sounds like the rfi is sending micro off into place it 
can't escape from and needs reset from cycling power.
Sometimes it helps if ac power to device is run through a toroid to keep rf 
from coming in on ground.
73 Paul K0UYA
----- Original Message ----- 
From: "Bob Maser" <>
To: "AMPS" <>
Sent: Saturday, October 11, 2008 10:53 AM
Subject: [Amps] RF Interference

> This may be a little off target for this reflector but maybe someone can
> offer up some advice, and it IS RF interference from a RF amplifier so 
> here
> goes.
> When we moved into this home about 6 years ago the garage door opener went
> belly up in the first 3 months.  I immediately went down to Home Depot and
> caught a sale for a Genie Excelerator garage door opener.  It was neat
> because it goes up really fast and has all the whistles and bells.  About 
> a
> month later I noticed that when I would go key down with the 3CX3000 amp 
> it
> would freeze up the opener and in order to unfreeze it, all you had to do 
> is
> trip the circuit breaker and reset it and all was well again.  Just 
> talking
> on SSB never seemed to bother it.  It was a pain in the *** so I called 
> the
> Genie folks and they sent me a replacement board.  The new board had the
> same problem.  At that point I started putting ferrite cores on the power
> cord and on the wires that go to the door button.  Nothing helped.  Next I
> built a cage out of 1/4" mesh and installed that around the whole motor/PC
> board unit.  This helped somewhat but it also made the wire antenna less
> sensitive so it would only activate the door when you got within 20' or 
> so.
> During all this time, I was having monthly phone conversations with the
> Genie "Tech Support".  They have logged 11 calls from me and they have 
> just
> told yesterday me that  they can't help me and they suggest that I go out
> and buy another opener.
> Has anyone else experienced this sort of problem and come up with 
> solutions?
> FYI, the 115V that the opener is hooked up to is a dedicated line with no
> other circuits going any where into the house.  Just for kicks, I plugged 
> it
> in to a wall circuit in our kitchen using a extension(with ground) and it
> still freezes up when the amp is being used.  Barefoot doesn't bother it 
> at
> all.
> Any and all help will be greatly appreciated.
> Bob Maser  W6TR
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