Sat dish causes RF interferance to audio??

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Old 01-09-2009   #1
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My System: Humax receiver 1.2m dish
Question Sat dish causes RF interferance to audio??

Strange question maybe... I'm an audio technician & at work I have a 1.2m dia dish connected to a Humax receiver tuned to Thor 2,3 0.8W for live opera broadcasts. All of that is fine no problems. I also have a separate recording studio, the dish being on the roof nearby it. since sometime around the dish installation I have been experiencing regular 'chirping cricket' like noises (possibly a radio beacon?) on the recording studio audio system which is no way connected to the sat receiver & hasn't had any new gear itself.
...so now I've had about enough of the mediteranian backing track (!) having tried numerous grounding / power checks etc I'm about to rip the dish down in an effort to cross it off the suspect list, but before I do. has anyone heard of a dish - even if it's unplugged from the receiver causing some kind of RF signal reflections / radiation that might cause this???

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Old 01-09-2009   #2
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My System: Triax 1.1m and Orbital 80cm Motorised Dishes. Various fixed Dishes. Eclectic selection of Digital and Analogue Receivers. Complex switching and distribution that SWMBO cannot fathom. Nor me.

Never heard of such a thing!

The only "active" component at the dish end of things is the LNB, which contains a Local Oscillator which operates at 9570MHz or 10600 MHz.

The prospective radiated power is infinitesimal and although you might think the LNB is plastic bodied, it is actually a sealed diecasting contained within a weatherproof enclosure.

It's far more likely that the cause is something like a Mobile Phone .............. I'm sure others can come up with other suspects.

Anyway, you can rule out the Dish simply by powering down the Receiver thus stopping the LNB Local Oscillator.

The Receiver itself will be metal enclosed, giving rise to a Faraday Cage effect and consequently just about eliminating that as a cause too.

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Old 01-09-2009   #3
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My System: 80cm dish, Pace MSS500 (analog) 19e 1m dish, SG-100 motor, Dark Gold 0.1. Pace MSP 200, Humax F1 VACI

Yes, I'd power down all your satellite kit and even de-point the antenna 90degrees and see if the problem goes away.

Have you got any radio hams near you which may be causing interference in your recording studio? If you look up RTTY and SSTV on wikipedia, there are some sample sounds. There used to be a radio ham near me with a half wave di-pole at 80m. He used to reak havoc on the FM radio and television sets.

Hmm.. thats got me reminiscing the old days of the russian radar sound called the 'woodpecker'.
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