Thread: 22KHz signal coupling through dual LNB

Can you connect the meter "in-line"?
LNB---Meter---Switch

Yes, might try that. But looks like the wife wants to watch TV now, not play with TV.

If you were to find 22khz, I wonder what a 2x4 multiswitch would do for it?
Certainly never heard anyone complain about this problem when using one.
Might cure your problem (whatever it is), even if it has nothing to do with 22khz.

Interesting idea, never used one before. So would I leave the existing selection as is and the 2x4 multiswitch is just inserted near the dual LNB?



Like this.

|-----|out #1-------LNBV .... RX1-----to existing 22khz & 1x4 switch bedroom
|
|dual LNB , , , , , , 2x4 multiswitch
|
|-----|out #2-------LNBH ....RX4-----to existing 22khz & 1x4 switch livingrm

Originally Posted by wrdavis

I have two Pansat 9200HD units, two 1M motorized dishes, and two 3 circular LNB dishes. Both setups are the same: the 1M dish is wired to Diseqc #1, circular LNB Echo 5 to #4, circular LNB Echo 7 to #3, and circular LNB Echo 8 to #2. The selected output from the Diseqc 4x1 switch goes to the 0KHz side of a 2x1 Encoda 22KHz switch. The output from the Encoda switch goes through the motor and back to the Pansat. The two outputs from the dual output C Band LNB go to the 22KHz sides of the two Encoda switches.

Okay, so you have five sources.
Four Ku band LNBs are on a 4x1 diseqc.
That output then goes through a 22khz Ecoda which lets you select those four LNBs or the one C-band LNB.
Somewhat like this hookup (Switch setups simplified) in the Switches Simplified FAQ.

Scroll down a little in the FAQ and read about Multiswitches.
There's no picture for hooking up a 2x4, but the words should make it clear. -

If you are using DiSEqC 2.0 switches or above they do have bi directional communication. It may be worth changing out one with a 1.x to see if this solves the problem.
Personally I see this as a receiver quirk and as Brian says induced ground voltage on class 2 equipment may well be the fault

Great information Anole.

I'm going to have to start doing drawings like you, instead of trying to to type a picture using _,-, & | characters.

Looks like two ways of attacking my problem.

First, if it is 22KHz coupling through the LNB and back into the other Pansat's switching. I'm using Ecoda 22KHz required to pass the 22KHz signal to my Diseqc 4x1 switches. So I could put the Traditional 22KHz switch in series with the output from the Ecoda to the C Band LNB. The Traditional ones don't pass the 22KHz signal, so IF that's the problem, should fix it.

Second, try the 2x4 multiswitch.

With shipping being the delay, seems reasonable to buy both, try them and see what works.

Took my scope this morning out to check for 22KHz coupling through the LNB. I see some, but have no idea if its enough to cause the problem. Even in shadow on the roof, the sky was light enough to wash out my photos. So the outdoor ones were enhanced to see the waveform better. All have the same time and voltage scales, AC coupled.

wrdavis, great photos thanks for sharing them. Sorry though, it does not convince me that 22khz is the problem. I look forward to your next steps

I agree, the signal through the LNB looks pretty small; to cause what I see as interfering from one system to the other.

I've tried running both systems from the same power outlet, and saw no difference.

The 22khz switch and 2x4 multiswitch idea fix is waiting for the mail to arrive in a week or so.

In the mean time I just put both systems on the same channel either Ku or C band to ignore the problem. But if that's the only thing I can do; might as well drop to only one system on c band and put a signal splitter to the other. No guarantee that would work, if somehow the diseqc switch is effected.

Have the switches and dishes been bonded together and grounded?

wrdavis, Brian has a valid point here. Your receivers are Class2 so currently they are grounded only via the coax as far as the metal cased C band LNB which is bonded to the dish but not grounded effectively or to the switches etc.
One other thought if your dual c band cables are cable-tied tight together induced RF on one may affect a weaker signal on the other particularly is the cable dielectric is crushed.

No they are not ground bonded together. Could try that while awaiting the parts I ordered. Doubt its RF coupling. The signal goes to zero on a wanted signal if the other Pansat has selected the opposite dish. But could try shortening the coax and separating them as well.

But today was spent re-installing s/w and op sys on my wife's computer.