[R-390] Re: Not So Much Off Topic...

Drew Papanek [email protected]
Sat, 20 Mar 2004 20:29:27 -0500


The other other Barry wrote:

>I joined a RC club a few weeks ago.

<snip>

>So, one plane was hit by a few seconds of a stray
>transmission on takeoff, and another was hit as it took off and made an
>uncommanded left turn into the woods where it was obliterated into
>several hundred pieces.

It was intermod, I tells ya, intemod!   Never woulda' happened if the 
receiver
in question had a 6DC6 front end and a tracking tuned IF section:)  Then
again, the plane would have stayed safely weighted to the ground...

>Does anyone  know where to find the info in that slice of the spectrum to
>find out what all is authorized to transmit? Maybe that would help in
>locating whatever was propagating to the flying field. Any other ideas?

The 72-76 MHz slice is jammed in between television channels 4 and 5.
Along with Citizen's radio service class C (radio -controlled  devices of 
many
more types than just aircraft) it is also allocated for land mobile 
communication
and  pager services (some of which run quite high power).

Once the aircraft gets any kind of altitude at all, it is open to invasion 
by these
sometimes strong signals.   The altitude need not be very high; note the 
great
increase in TV or scanner signal strengths encountered when raising the 
antenna
from, say, 10 feet up to 20 feet.

I don't know of a specific place on the 'net to find the allocation 
information (maybe
Roy knows?)

Drew

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