High frequency signal loss on Thor

sandersc

I recently installed an Invacom 0.3dB LNB on a 1.1 Triax dish. On Thor
1W, I receive strong signals at lower frequencies, but by 12643H I am not recieving very much at all. At higher frequencies than this, I get nothing at all.

Is this down to the transponders or could it be how I fitted my LNB?

satelliteman

More attenuation higher up the band you go yes, but this will be LNb, dish alignment or LNb skew causing you problems. From your location the LNb skew should be almost vertical. Also check the LNb focal point.

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sandersc

I checked my LNB and dish. It is near enough perfect, so I am suspecting my LNB is faulty or perhaps the Invacom doesn't go up to 12723H ?

sandersc

Just checked LNB frequency, should go up to 12750. Perhaps receiver is the problem, it quotes frequency range950 - 2150MHz, could this be the problem?

guest

12735 (Highest Ku Band TP on Thor) - 10600 (High Band LNB Local Oscillator) = 2135 MHz.

12750 (LNB spec.) - 10600 = 2150 MHz, so they are "matched".

So that is within spec. for the Receiver (just) - but what does the spec. actually mean ......... ?

guest

Sorry - should clarify my comment about what the spec(s) actually mean: I have a Humax Receiver which performs poorly at the top of the Band too.

Also, Satelliteman referred to the possibility of a tailing off of performance earlier in the Thread.

sandersc

I have no problem with high frequencies on Astra at 19E so it must be my set-up. I have about 55m of cable so perhaps this could also be a factor?

Robbo

Could be, the attenuation of the cable at the higher frequencies is greater. What cable are yoou using?

Maybe you'd do better with 125 rather than 100 type.

pedro2000uk

The Invacom isn't the best match for the Triax 1.1.. (although that won't account for the unusual Hi freq' cut off)

where is the LNB located as regards its position in the LNB holder... middle / back/ forward etc.. for best signal

satelliteman

Do you also have another LNb to try first to eliminate the Invacom itself ?

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sandersc

I tried the LNB in all positions with all skews. Bent the lnb arm to check angle etc etc. The LNB/Dish is set up perfectly. I heard all this stuff about skew, but on 1W you can twist it all over the place and the signal stays the same.

I have just replaced a faulty Titanium 0.2dB. I won't be getting any more of those. I might buy a MTI Blue Line 0.3 dB Universal LNB, but I don't have a spare.

Pedro2000uk, what LNB works better with a Triax?

I bought quality cable (i'll check the ref though). I am going to try the receiver next to the LNB when the weather improves! If that works, I'll get a signal amplifier.

Thanks for all the suggestions.

pedro2000uk

We often modify the Triax 1.1s to a shorter focal length (the one's without the folding arm anyway) to gain c. 35% .. most LNBs favour c. 15mm- 25mm shorter. You can get a long neck LNBf like some Edisons or MTI Supers to get closer instead of mod'ing but then you are limited to just a few lnbfs.

The Smart Titanium are OK - too many people use them and they do well 'usually'- not seen one fail actually.

It is probably best to just get any LNB to test for that high freq' problem first and that it is not in the receiver and perhaps consider that a fault (short etc.) hasn't caused it (and had damaged the Titanium).

It could also be ground based interference in the direction of 1w.

We've found several LNBs beat the Invacoms on a 1.1.. including the Titanium .. the Invacoms (mainly quads) seem to do well on big dishes (1.8s- 2.4s and bigger) on very weak signals like 28e's 2d in Spain & 7w H's here.

sandersc

Thanks Pedro.

Perhaps I should take the LNB out of the arm and move it closer to see if this helps. sliding it within the holder had no effect.

I saw your other posts about making the adjustments to the holder and the arm, so if I can see an improvement, I'll give it a go.

Any idea where I can get an MTI Super? I can see the MTI Blue Line 0.3 dB Universal LNB, but it doesn't have a long neck.