Not getting high SR stations on 2nd LNB

[momtic]

Hi all,

I have a strange problem. Here is my setup:

southwest Germany location
85 cm dish with 2 LNBs, one on Astro, one on Hotbird
Diseq switch on dish mount. HB is channel 1, Astra is 2
(crappy) motor drive with manual buttons - no control from receiver
Humax 5400 with reasonably recent ToH

Here is the problem. I installed two LNBs to avoid using the motor,
which is loud and unreliable. I can get plenty of stations from
Hotbird, but only a few from Astra. By looking at these few, I found
that the receiver was only finding Astra stations with the lowest
Symbol Rate (SR), specifically 22000 5/6. I could not even manually get
signal from known transponders with higher SR (i.e. 27500 3/4).

I moved the dish over to point the other LNB at Astra, and the
receiver had no problems finding high SR stations. For what it's
worth, I have also sometimes noticed that it takes some time for
signal to come through when I switch between stations on different
satellites, and sometimes I need to pick a third station to "force"
the switch.

In principle, I can do more tests, like switching LNBs, cables, etc.
but it involves climbing up on the roof - zero fun.

Any ideas? Thanks in advance...

 

[loftyj]

How long have the LNB been in place, it could be the LNB that is not switching is faulty, try switching the LNB over in there brackets instead of moving the dish, this should tell you.

 

[momtic]

Thanks for the response - so there is a (believable) failure mode for LNBs which prevents them from delivering signal from high Symbol Rate channels but they otherwise seem fine?

Also, when you say "the LNB that is not switching", do you mean switching from one LNB to the other, or switching from low to high SR within one LNB?

Thanks again...

 

[loftyj]

Switching from one reception frequency band 10700 to 11700 GHz. to the other band 11700 to 12750GHz thay are selected by a 22KHz tone on the LNB power supply

 

[rolfw]

The only thing that I can think of, is that the higher symbol rates are not in the list for that satellite, I've certainly not come across the problem whereby an LNB would not pass the higher symbol rates.

 

[momtic]

> The only thing that I can think of, is that the higher symbol rates are not in the list for that satellite

No - this isn't the case. I tried manually setting the SR and then looking for signal...nothing.

This afternoon, I replaced (both) LNBs with new ones (0.3 db). The one that was causing problems was at least 8 years old and looked pretty beat up. In any case, I can now find high SR stations using the same technique that failed before. FWIW, I also replaced the outside wiring. Interesting.

The other problem I had remains, namely it can take a long time (or forever) to switch between satellites (I have a Diseqc switch outside on the dish). I have discovered that I can force the switch by going into Manual Search and manually switching the polarization back and forth.

Any ideas on why switching is so touchy?