Skew Adjustment

[cyberham]

At the risk of stating the obvious, I have never experienced such improvement as when I tweaked my Ku LNB skew yesterday on my motorized dish. I have always installed it with its reference mark exactly at 0 on the LNB holder. The motor skews the whole dish as it turns.

Since I had been having reception trouble of NBC East on 103W for weeks ever since I temporarily installed a different LNB, I decided to investigate. This was after pulling lightly on the dish edges without finding any improvement.

I searched for maximum signal from NBC West by rotating the LNB on either side of 0. It turned out that setting the LNB off zero maybe by 10 degrees improved reception. When I next checked NBC East it was 10.8 dB and stable (last night reaching 11.0 dB). Also, most signals across the arc have improved measurably and significantly.

The moral of this story is to do everything according to procedure, but then tweak using actual measurements at the end. I monitored as I tweaked using my smartphone at the dish wifi-connected to my Edision receiver in the house.

 

[comfortably_numb]

How about the NBC "MUX?"

 

[cyberham]

Now that's another story...those channels have always been tough here. I'll be watching for them. I think they're only active weekdays? If I can get NBC East and DW, then I'm happy. And I can now.

Here comes Blacklist (tonight!).

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[arlo]

Of course the obvious. Your lnb is all the way back in it's bracket. I take it that signal decreases as you slide it forward. How about if you move the mount back physically so you have wiggle room to move the lnb in and out for peak? Also it's a good idea to switch back and forth between H & V tp's while you adjust skew and peak signal for that happy medium.

 

[iceman382]

At the risk of stating the obvious, I have never experienced such improvement as when I tweaked my Ku LNB skew yesterday on my motorized dish. I have always installed it with its reference mark exactly at 0 on the LNB holder. The motor skews the whole dish as it turns.

Since I had been having reception trouble of NBC East on 103W for weeks ever since I temporarily installed a different LNB, I decided to investigate. This was after pulling lightly on the dish edges without finding any improvement.

I searched for maximum signal from NBC West by rotating the LNB on either side of 0. It turned out that setting the LNB off zero maybe by 10 degrees improved reception. When I next checked NBC East it was 10.8 dB and stable (last night reaching 11.0 dB). Also, most signals across the arc have improved measurably and significantly.

The moral of this story is to do everything according to procedure, but then tweak using actual measurements at the end. I monitored as I tweaked using my smartphone at the dish wifi-connected to my Edision receiver in the house.
View attachment 154187

Excellent advice. It's all about experimenting to tweak the last bit of signal. I would also add to try moving the LNB back and fourth to tweak the focal point of the dish for maximum signal.

 

[comfortably_numb]

I think they're only active weekdays

24/7

 

[cyberham]

Of course the obvious. Your lnb is all the way back in it's bracket....

I moved the LNB forwards and backwards. Its current position gives the strongest signal. I could try drilling another hole in the LNB arm a little further back and moving the LNB back. Not a bad idea.

I will try duct taping it a little further back first.


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[cyberham]

24/7

Noted. Back to the dish.

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[a33]

If the LNB holder might not be in the optimal distance from the dish, I would also check (by taking the usual measurements) if it is (or isn't) in the proper offset angle to the dish.

Greetz,
A33

 

[cyberham]

We'll see. It is the correct holder for the dish so it should be located correctly. But I'm going out into the sunshine with smartphone and large roll of duct tape. I've been watching Red Green on Heartland.

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[cyberham]

I could not improve on the received signal by positioning the LNB in another location (even using duct tape). I found that shimming the bottom front of the bracket with a thin flat washer caused an improvement of maybe 0.2 dB. This effectively pointed the LNB very slightly lower on the dish (A33!).

Final daytime NBC East is 10.8 dB peak. NBC West is 11.0 dB. And DW is 10.2 dB. These are excellent for what I have ever received with this dish. These readings will likely go up by 0.2 dB at night. I'm satisfied.

CN: I have the 11910 4-channel mux at 8.1 dB peak right now. Picture on each channel is perfectly clear and stable. That's when I walked away from the dish.

As a reference, my 1m fixed dish has following readings: NBC East 10.3 dB; NBC West 10.4 dB; DW No lock; 4-channel mux No lock.

 

[catamount]

Cyberham, if you ever come up to Moncton I'll give you a 75E dish plus a proper mast mount (possibly2) for your
one metre dishes. Send me a conversation if you are interested.

Catamount