LNB Blinder (Interference Reduction)

[Keith Brannen]

I am in very good area for AMC4 (101) (EIRP of at least 50) so am able to get very good signal quality on all FTA channels. This is with an LNB which is six degrees off centre on a 60e dish. The lowest is 45 (threshold on a Pansat is usually around 30 for most channels) and a lot are quite a bit higher. Recently one scrambled channel became ITC (S*t*nt*) which I really want. Naturally, for some reason (probably because I really want it), it has the worst signal quality (10-19 usually) with major pixelation and is totally unwatchable. Only once since the channel became ITC has it hit the 30 mark.

I did try peaking the LNB on it, but with little success, and what little I gained (may be a point or two) I gave back up as it caused loss on the other transponders.

On Tuesday I was out and was going to do another attempt at a minor tweak. Anyhow, I was basically just experimenting to see if I was getting interference from another satellite and could somehow block it. So I grabbed a wooden paint stir stick which was lying on the ground and placed it beside the LNB and tilted it inward. Imagine my total surprise (and great delight) when the signal went up, and not just a bit, but up to a stable 27-30! Take the stick away, and back down to 15-19. So I temporarily installed a plastic lid in place until I had time last night to manufacture something more stable and lasting (and not so funny looking as the plastic lid).

The photos below of the "blinder", as I call it, are the finished project, and my signal has been without any pixelation and has been stable at 28-33 since I mounted it. There has been no loss at all on any other channel (and in fact transponder 11860 also seems to have gained a bit) which is surprising to me, since the edge of blinder projects across a portion of the LNB face.

Definitely well worth the effort to experiment!

 

[guapoharry]

Hey, that's pretty cool.

What do you suppose is happening there? Noise from the earth? Not enough scalar in the LNBF?

 

[Keith Brannen]

Hey, that's pretty cool.

What do you suppose is happening there? Noise from the earth? Not enough scalar in the LNBF?

Right next to the dish is a wooden wall, so I don't think it is noise from earth (or the wall!), especially since it only seems to be the one transponder that is really affected.

I have checked the other satellites next to it (103,105,107.3) and the only active transponder that I can see (from lyngsat) that could be affecting it is a Digicipher 2 transponder on 107.3. It may be strong enough to be the problem (and the Star Choice transponders are strong here).

I know from working with multiple LNBs that the farther out you go from centre, the greater the possibility of bleedover from other satellites. Probably with the 60e the separation blurs considerably faster that with my other dishes, and even though I do get good signals in it, being a smaller dish the signals are weaker to begin with (than say an 80cm) so it is more susceptible to interference from bleedover.

 

[tvropro]

I am in very good area for AMC4 (101) (EIRP of at least 50) so am able to get very good signal quality on all FTA channels. This is with an LNB which is six degrees off centre on a 60e dish. The lowest is 45 (threshold on a Pansat is usually around 30 for most channels) and a lot are quite a bit higher. Recently one scrambled channel became ITC (S*t*nt*) which I really want. Naturally, for some reason (probably because I really want it), it has the worst signal quality (10-19 usually) with major pixelation and is totally unwatchable. Only once since the channel became ITC has it hit the 30 mark.

I did try peaking the LNB on it, but with little success, and what little I gained (may be a point or two) I gave back up as it caused loss on the other transponders.

On Tuesday I was out and was going to do another attempt at a minor tweak. Anyhow, I was basically just experimenting to see if I was getting interference from another satellite and could somehow block it. So I grabbed a wooden paint stir stick which was lying on the ground and placed it beside the LNB and tilted it inward. Imagine my total surprise (and great delight) when the signal went up, and not just a bit, but up to a stable 27-30! Take the stick away, and back down to 15-19. So I temporarily installed a plastic lid in place until I had time last night to manufacture something more stable and lasting (and not so funny looking as the plastic lid).

The photos below of the "blinder", as I call it, are the finished project, and my signal has been without any pixelation and has been stable at 28-33 since I mounted it. There has been no loss at all on any other channel (and in fact transponder 11860 also seems to have gained a bit) which is surprising to me, since the edge of blinder projects across a portion of the LNB face.

Definitely well worth the effort to experiment!

Another Professional Satellite Guys Custom Modification Gotta love it.

 

[Keith Brannen]

Another Professional Satellite Guys Custom Modification Gotta love it.

Thanks. It must come with the addiction... I mean hobby, always try to eke out as much signal as possible, no matter how!

 

[melgarga]

I'm calling my broker as we speak. "Dump the pork belly futures, and put it all in paint stir sticks!"........lol

Way to inovate Keith!

 

[turbosat]

What is that made of? Plastic will still pass microwaves, did the gadget work because it physically pushed the lnb-face more toward the center of the dish? It's puzzling, lol.

 

[Keith Brannen]

What is that made of? Plastic will still pass microwaves, did the gadget work because it physically pushed the lnb-face more toward the center of the dish? It's puzzling, lol.

It is made of hard plastic (from an old snow shovel) and it doesn't pass any signal if placed directly in front of the LNB. The plastic lid I used as a temporary blinder does pass signal when placed directly in front, but when it was angled the same way as you see the permanent one, it did stop the interference (either it is very weak interference, or the angle deflected it enough).

It doesn't touch the LNB (though it is very close, little less than a 1/8 inch away), as I wondered the same thing you did when I first was trying it.

 

[pedrogarcia]

Nice one Keith!
Had you been in dryer climate I'd suggest removing the plastic cap for a few extra points gain and if necessary repacing with a thinner mebrane

 

[Cadsulfide]

Cool!

 

[Cham]

I've had to re-position my Wi-Fi router in the past because it was interfering with the satellite reception (2.4GHz). Maybe someone has one nearby that you are able to block with your "filter"?
In my situation it caused interference with C band reception, couldn't pick up one satellite at all after I installed the router (think it was AMC-1). Made it easy to trace the problem. Must be poor filtering in the router's transmitter output or the signal gets into the IF at the satellite receiver or LNB. I also switched to a directional grid antenna for the router directed away from the dish(s) but just moving the router made the difference.
-C.

 

[Keith Brannen]

I've had to re-position my Wi-Fi router in the past because it was interfering with the satellite reception (2.4GHz). Maybe someone has one nearby that you are able to block with your "filter"?
In my situation it caused interference with C band reception, couldn't pick up one satellite at all after I installed the router (think it was AMC-1). Made it easy to trace the problem. Must be poor filtering in the router's transmitter output or the signal gets into the IF at the satellite receiver or LNB. I also switched to a directional grid antenna for the router directed away from the dish(s) but just moving the router made the difference.
-C.

Thanks for the information, I hadn't thought of that. While our network is wired, so it can't be the problem, it it possible it could be one of the neighbour's (my son's computer detects 6 wireless networks).

Anyhow, tomorrow I am going to see if I can determine where the interference is coming from (earth based or satellite) by trying to block the interferring signal a few feet from the dish using a metal snow shovel (have used this before to determine placement of other dishes so as not to interfere with each other). The neighbours' already think I'm crazy (from this satellite "hobby") so waving a snow shovel around in front of a dish will only be further confirmation in their minds!

 

[tvropro]

The neighbours' already think I'm crazy (from this satellite "hobby") so waving a snow shovel around in front of a dish will only be further confirmation in their minds!

That's pretty good. My neighbors think Im nut's till I tell them everything I get and the low low cost I spend on my subscription channels. Then there like WOW

 

[Keith Brannen]

It is made of hard plastic (from an old snow shovel) and it doesn't pass any signal if placed directly in front of the LNB. The plastic lid I used as a temporary blinder does pass signal when placed directly in front, but when it was angled the same way as you see the permanent one, it did stop the interference (either it is very weak interference, or the angle deflected it enough).

Just a correction to the above statement. The hard plastic I am using DOES NOT block the signal if place directly on top of the LNB face. However, if you angle it (as in lift the bottom away from the LNB face), it does begin to block the signal. Interestingly, if you angle it from the bottom, the horizontal is affected more, and if you angle it from the side, the vertical is more affected.

 

[whatchel1]

Earth based

By looking at you setup I would lay odds it earth based. Unlikely the device you are using could do anything for a sat to the E of the feed.

 

[Keith Brannen]

That's pretty good. My neighbors think Im nut's till I tell them everything I get and the low low cost I spend on my subscription channels. Then there like WOW

Lucky for you with your 4DTV! Unfortunately, with the loss of the Equity channels, FTA is an even harder sell for people to understand (and I think the fact that I can be out late at night and in the winter "playing" with my dishes has tainted their views)!

 

[1ADAM12]

This reminds me of LoTech. He came up with a Styrene cup to reduce interference between RTV and LEO 1.

Consider your device may be working not to block but to ever so slightly changing the L.O. of the lnbf like a dielectric plate.

 

[SatelliteAV]

Consider your device may be working not to block but to ever so slightly changing the L.O. of the lnbf like a dielectric plate.

Correction: Dielectric inserts do not modify the Local Oscillation frequency. Dielectric inserts mechanically limit the reception to a specific signal phase.

The blinder maybe attenuating interference from either terrestrial or adjacent satellite.

 

[tvropro]

Lucky for you with your 4DTV! Unfortunately, with the loss of the Equity channels, FTA is an even harder sell for people to understand (and I think the fact that I can be out late at night and in the winter "playing" with my dishes has tainted their views)!

Ya FTA is a hobby thing for the most part. I sold a client on the DSR 410 idea last summer and he's saving $50.00 a month now over Comcast. My neighbor pays $245.00 a month for Comcast I spend about $20.00 with the 4D. Comcast want's for basic by me with the local HD channels $139.00 a month. Thats crazy.... Thats Extortion.

 

[Keith Brannen]

Spent some time outside (great weather today, going back out after this post) trying to determine where the interference is coming from.

Using a variety of objects (metal snow shovel, plexiglass, wooden board, myself!) I was able to determine it is not earth based either from underneath, either side, back, or front, when checking below where satellite signals hit the dish.

When attempting to block out signals to the east of AMC4, it did appear to have some effect, however, due to the width of the beams that hit the dish as opposed to the focused signals at the LNB, it was not possible to duplicate the excellent results achieved by the blinder.

Back out to the lawn chair, and a well deserved rest!