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DirecTV RFI on 40M Aug 6th 2015, 21:02 2 2,173 on 21/9/16

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DirecTV RFI on 40M K4DER on 6/8/15
I thought the old days of TVI were over, but apparently not.

I have DirecTV satellite service and never had a problem until my old receiver died and needed to be replaced. DirecTV drop-shipped me the new receiver and I installed it in minutes. It worked just fine until I loaded up on 40 meters.

When I tuned up, the receiver came on all by itself and as I spoke, the receiver went crazy. It was if someone was pushing the buttons on the remote control as fast as they could.

I did some minor troubleshooting and asked friends on the air but no solution was found. I called DirecTV and explained the problem and they had never heard of it so I ordered a service call.

When the technician showed up, I explained and demonstrated the problem. He had never heard of this before in his 14 years with DirecTV. We tried a number of things and none worked.

The technician called DirecTV and they could offer no solution to the problem so he went one step further and went to some online forums and found other hams who experienced the same problem.

The old receivers were enclosed in an aluminum chassis but the new ones were enclosed in a plastic case. Bingo, the cause was identified, shielding.

Some hams solved their problem by wrapping the new receiver in aluminum foil. And that appeared to work so we tried it and sure enough it worked, no more interference. However, the aluminum foil covered up the vent holes and I was concerned about venting and heat buildup and it looked awful.

Fortunately, I still had my old receiver and since the new receiver was almost the same size (new one is a bit shorter), I decided to remove the aluminum cover and place it over the new receiver.

The screws holding on the cover were security screws which I did not have a tool for so I used the brut force method of grinding the heads off. Once I had the cover off, I fabricated a bottom using aluminum flashing and aluminum tape. I had to spread the sides of the old cover about 10 degrees to accommodate the width and made a connection to the bottom of the receiver , which is aluminum, with aluminum tape.

Testing it, I discovered my TVI problem had been resolved and the receiver could breathe and dissipate heat. I was also pleased that I could recycle a portion of the old receiver in the process.

Bill Wheaton
K4DER Concord, VA

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