On 14 Jul 2006 14:05:42 -0700, "rb"
wrote:

I bought a FM wireless transmitter to rebroadcast stuff from my PC
around the house. The only frequency I could find was 104.1 that was
clear without a station. But all of a sudden, now when I am
broadcasting my stuff, I pick up planes instead. How can this be? I
know it is from planes, as I hear words like "Southwest", etc. Without
my transmitter on, all I hear is static on 104.1
but when I turn on my transmitter, the planes seem to over ride my
signal.


OK...here's my take on this...
I agree with RST Jim and John "Nospam"

Such mixing does occur...I maintain ground radios at CLE...Cleveland
OH. Our main transmitter site is on the main road next to the
airport. 10-watt radios on 60-ish foot towers....the 'slant range' to
the antenna could be ~150 feet if driving by. I have experienced
numerous instances of interference to FM broadcast stations as well as
2m (144-148 Mhz) amateur radio reception when driving by the site.
Several friends have also experienced this and queried me about it.

This could also easily happen with a nearby micro-power FM
transmitter and a much higher power 25-50W (?) airborne transmitter at
a few thousand feet away.

Looks like the FCC specs are 250 microvolts /meter measured at 3
meters. And I bet the transmitter in question is WAY less than
that, most are. I have used several FM transmitters meant for MP3
player use in a car and found them to be poor...and they only have to
go a few feet, even to a rear fender antenna.

On a similar note... I once had a complaint that our 2m( 146 MHZ)
Skywarn transmissions were interfering with Airband
communications...from someone using a scanner. He was sitting out in
front of our National Weather Service office (on the airport) at the
time, about 150 feet from the 2m antennas!

He was very concerned, but once we explained what had happened, AND
that I worked at the airport AND we hadn't had problems in several
years of operation...he relented...

--Don Byrer

Hey "rb"...you haven't posted since to say "thanks", ask further
questions, provide further info as requested or even to disagree.
How about it???



Don Byrer
Radar Tech & Smilin' Commercial Pilot Guy
Amateur Radio KJ5KB
kj5kb-at-hotmail.com

"I have slipped the surly bonds of earth; now if I can just land without bending the gear..."
"Watch out for those doves...smack-smack-smack-smack..."