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C-Band Satellite reception "burps"

speakerman said:
I agree with ChiefEngineer. 93.9 Indy had the same problem years ago with a C-dish on the studio high-rise roof that was aiming in the direction of the airport to the SW.

It took a spectrum analyzer to find an intermittent signal just outside the C-band that was overloading the input. With further investigation I determined it to be aircraft landing approach radar that mostly showed up during peak flight times on a particular approach. A Microwave Filter band-pass filter between the feedhorn and the LNA took care of the problem (after much grief).

I'm not sure if the airlines are still using that frequency range but it would be worth checking out. It doesn't take much power to overload the input when you have an air-mobile source tracking within the focal point of the dish. The spectrum looked like a comb generator with REALLY hot spikes.
Click to expand...



I live 10 miles due east of Chicago O Hare in between the two E-W runway approaches.
I work at locations directly under two other aproaches, the NW-SE and the NE-SW.


In each of these locations, @ 10 miles on the E-W, and at .5 mi on the two diags. I've had these radars turn on my laptops from standby.
Over 15 years, this has happened 4 times.
 
There are approach systems that operate just above C-Band (which is near Transponder 23 where ABC lives). Military radar also operates near C-Band, and, I suspect, at various other places in the band depending on the abilities of the last maintenance tech. www.microwavefilter.com

Call them up, ask for an "AWACs" filter. Mounts on the feedhorn ahead of the LNB. It's not very expensive, and will keep this kind of sporadic TI out of your system.

I would also suggest powering the LNB with an independent supply, instead of a receiver. Just makes life easier. You can buy one at places like DawnCo, or make one in a mini-box with an 18 volt three-pin regulator, suitable sized transformer and the usual power supply parts. Just feed the RF through a DC block to the receivers (available at Radio Shack).
 
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