[Elecraft] K2:problems with frequency changing

Mon Feb 24 18:30:08 2003

Is that a "coded" garage door opener or the simple "carrier detect"
variety? I thought the simple "carrier detect" type that opened the door
any time a signal was sensed on the proper frequency were pretty well
out of use many years ago.

If it's the latter, you have probably found a frequency where a harmonic
of your K2 lands on the garage door frequency - which is up in the VHF
range. That's why they have fallen out of use. 

When garage door openers first became really popular in the late 1950's,
there was hilarious situation in which some company canvassed a section
of Burbank, California (near Los Angeles) installing hundreds of garage
door openers in the subdivisions there. The only problem was that
Burbank Airport has housing right up against the touchdown end of the
runway. I used to ride airlines in there and it looked like those real
tall TV antennas were getting close to our wingtips by the time the
houses ended and we were over the end of the runway. 

Anyhow, there came the fateful night when an airliner keyed up his VHF
radio as he was in final approach over those houses - and literally
hundreds of garage doors flew open all at once with the lights shining
out onto the driveways. 

It caused quite a bit of chaos for some time afterward.

If you have the current "coded" type of door opener that requires a
signal on the right frequency and with a certain code sequence to
activate the mechanism, you probably have RF getting into the logic
circuits. You might try a simple clip-on RFI suppressor from Radio Shack
on the power cord - or several of them - right up against the motor
housing. But if it's very frequency-sensitive - only happening near a
particular frequency - I'd suspect that it's more of a harmonic problem
being picked up by the receiver than simple r-f intrusion through the
power line. In that case there isn't much you can do except upgrade your
door opener - or remember to close it after operating. 

Ron AC7AC
K2 # 1289

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Gregg R. Lengling
Sent: Monday, February 24, 2003 2:32 PM
To: [email protected]; [email protected]
Subject: Re: [Elecraft] K2:problems with frequency changing

I don't have the answer...but it's better than my problem.  If I tune
the KAT100 autotuner on 7,258...my garage door opens......I have to
remember that when I'm on 40 meters or the door stays open all night.

Gregg R. Lengling, W9DHI
K2/100 SN 3075