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DirecTV and TVI Help needed

Jun 30th 2012, 17:37

W4JPA

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
This subject has been up before but I can't find a solution (Several folks note they do not have problems).

I do not get any interference on terrestrial TV in my shack or when I use the terrestrial antenna to feed the TV in the front room. I.E. Problem only occurs when I feed the TV in the front room with DirecTV (via HDMI cable). We get a marked pixelation and "Loss Of Signal" message, and the sound disappears. (no audio breakthrough).

No problems occur using a dummy load or my OCF dipole on 20 meters. Problems appear on 17 meters using the OCF Dipole and both 20 and 17 meters using my Hex beam. (other bands not tested)

I've checked all connections, run extra ground to dish, rear of DirecTV receiver and my rig. Not quite sure what to do next.
Jun 30th 2012, 17:50

KB0HAE

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
The answer might be a better hdmi cable. A friend had a similar problem using a cable purchased at Staples. A better cable bought online helped considerably.
Jul 1st 2012, 11:45

W1VT

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0

How long is the cable? While inexpensive cables work up to 16 feet, better quality is needed for longer lengths. You may also be picking up common mode interference on the cable--it may be necessary to wrap the ends of the cable around type 43 ferrite to decouple the RF.

In theory, while good grounding can decouple RF from conductors, in practice, simple ground rods and wires don't have a sufficiently low enough impedance at all frequencies to be effective.

Zack Lau W1VT
ARRL Senior Lab Engineer
Jul 2nd 2012, 14:47

AA6E

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
I would look at your DirecTV setup. Is there a long run between the dish, the receiver box, and your TV? Does it run close to or parallel to your antennas or feedlines? RF could be conducted in this way and on the outside (?) of your HDMI cable. Ferrites on the satellite coax (or even on the AC leads to your satellite Rx) might help.

73 Martin AA6E
Jul 3rd 2012, 02:32

W4JPA

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
Thanks for the feedback and ideas. Here is what happened;

The wall bracket connecting earth wires from the transducer head and the coax outers to a ground strap was just waving in the wind. The earth wire was so corroded it had broken off and no ground strap had been installed.

A 8’ ground rod was pushed into the ground and a good, solid copper wire run up to a new connection bracket. A new ground was wired to the dish lugs. A quick test indoors on 20 and 17 meters using both the OCF Dipole and the Hex passed with flying colours. Not even a trace of interference.

I hope this helps anyone else with similar problem

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