Cband interference with 90cm and 1M

[vfrjim]

Recently I noticed that if my BUD was in a certain position with the Cband LNB attached, I would get lower signal levels on both my 1m Winegard and 90cm Geosatpro. If I remove the coax from my Motorola 922(cband only coax), the signal jumps back up where it belongs. I mean, not just a little drop in signal, for example, on SBS6 (ONN channel), quality on my Coolsat would go from 91% to 69% with my BUD on G1 with LNB connected, I remove the Coax and it goes back to normal. Has anyone else ever noticed this problem? Un fortunatly, my BUD is located behind my smaller dishes and there is no other place I can locate them due to Trees

Jim

 

[Hermitman]

I'll give it a shot. If your coax or lnb is radiating some sort of interference signal, I'd check the coax shielding for proper grounding. Make sure both end connectors are properly installed and the ground shielding is not touching the center wire. Also make sure the ground system for your house is in good working order. Good luck and have fun.

 

[vfrjim]

Well, I think that I figured it out. I disconnected the cband coax from the Diseqc @ the 1m/90cm dishes and left it connected to the 4dtv receiver and I no longer have the problem. So, now I wonder if replacing the Diseqc will solve the problem?

 

[Hermitman]

Having a switch in the system is a whole new ballgame. Not knowing how you have set up the switch, generally check that the antennas are in the ports you've chosen in your receiver and the receiver is set up properly for the switch. You can also switch ports (after powering off the receivers) and see if the problem follows the changes. If this is a new problem, did you do any changes to your system or did the problem just pop up. Or has it always been this way. I think I'd do some more troubleshooting and configuring before swapping out parts. But then that's fun for me and I'm cheap. Good luck and have fun.

 

[vfrjim]

Put it this way, I did not know that it was causing a problem and I was chasing "ghosts", not knowing that the input from the Cband dish was causing this problem. I did not know why the signal level changed, I finally found out "part" of the cause, so it looks like I will swap out the Diseqc and see what happens. Thanks for your suggestions.

 

[vfrjim]

I have found a solution to my problem with the interference that I was getting from the Cband dish and my DisecQ. From a little experiment in dropping the signal level on the Cband input on the DisecQ using various connectors (extra splitter, switch, another DisecQ) with mixed results. Jimmy, from DVBhardware suggested that I use a 3 or 6 db attenuator on the Cband input and now I have NO problems with the signals going down on my KU inputs! I never knew that having too much signal from a source would KILL a DisecQ, rendering it useless. I am now happy with full use of all my dishes.

Jim

 

[Anole]

damned if you do; damned if you don't !

Yea, congratulations on the fix.

As I was reading your (old) thread, I was reminded that the db of isolation between ports is not all that great on diseqc switches.
And I wondered if your Cband LNB was separately powered and aimed at a strong satellite.
Apparently it was.

Normally, the switch only powers the desired LNB, so this is not a problem.
But, in a recent thread, one member complained of long lock-time when switching to one of his LNBs.
Obviously, it was suffering warm-up drift.
And I suggested he power the circular LNB through a separate connection, if it had two outputs.
I guess that's a two-edged-sword, eh?

Your post serves as a timely reminder for others.
Good info!