3rd LNB blown in under two years

[dcapper]

I just don’t get it. The dish is grounded with an 8ft ground rod. I have a lnb protector and yet again, I have a blown lnb. Can someone recommend a lnb that can survive lightning strikes in the area? I know it’s not hitting the dish. I have been using Titanium PLL’s.

[Imsomebody]

Can you not add surge protection.

[dcapper]

I did. Took that out too. I think it’s the Titanium brand. It doesn’t seem to handle any foreign voltage at all.

[Terryl]

Did you use a ground block, or an inline gas dish-charge device??? <br />
<br />
All a ground block does is ground the coax shield, a gas dish-charge device protects the center conductor, this would protect...

[dcapper]

I used an inline gas protector from amazon. I just ordered some cheap lnb’s out of China. I’m tired of throwing money at this. I’m going to order one out of Toronto too so it will be here in a week but I’ll just stock pile Chinese ones. At least when I come to the cabin, I can swap out one and still have tv. We have bad lightning from May until July here.

[Terryl]

How close to you were the hits???? If you blew the in-line gas dish-charge device then it may have been a direct hit. <br />
<br />
If within a mile or so the EMP off a big one can wipe out most stuff. <br />
<br />
In...

[steveOtoo]

I have intentionally never grounded any of my dishes or coax and have never had a problem and i live in florida. I believe grounding can cause a higher potential to ground and cause an easier path for potential surges to your equipment.................

[dcapper]

I might remove the grounding. My dish network and bell both never had a problem and both of those are not grounded. The dish network dish is about 6 feet from the bud. I tried another receiver but it still didn’t work. So now I have a burnt dms one and two Titanium PLL’s. Watch the Chinese ones will work better. Hehehe.

[Terryl]

I have intentionally never grounded any of my dishes or coax and have never had a problem and i live in florida. I believe grounding can cause a higher potential to ground and cause an easier path for potential surges to your equipment.................


Well it's very dangerous to not ground an RF system with an antenna outside up on a roof, (or other location) you have been very very lucky.

I've seen what happens to someone who didn't have a grounded a system,(install mistake) they took a hit and it got them from across the room, you could see the smoke trail from the coax leading in from outside, the burnt CATV receiver, pieces of the TV still lying around and the burnt carpet where they where sitting.(carpet was burnt in many place's)

I was called in as a consultant for the arson investigator, the place smelt like a burnt pork sandwich.

I'd rather loose equipment then risk getting BBQ'ed.

[Terryl]

The Dish LNB's have internal MOV's on the coax outputs.

[dcapper]

I’ll leave the grounding on and hopefully storm season is almost over.

[Terryl]

You don't have a lightning rod system do you???

[dcapper]

No. The dish is about 100 feet from the cabin. I think it’s lightning in the area.

[Terryl]

Well since it's a "C" band setup with the LNB's up inside a cone, can you try this, wrap the LNB in one layer of 1/4 inch foam, (packing stuff), then one layer of aluminum foil, (except for the eye) then a layer of 1/4 inch foam, then one more layer of aluminum foil, do not let the two layers of aluminum touch each other, ground this layer.

This will create somewhat of an EMP shield, I don't know how effective it will be but it has worked on 7 GHz stuff in the past.

[dcapper]

I'm going to try that. I was looking in the box that I received my lnb in. What is the fibreglass plate used for? I've never installed it.

[dishuser]

I'm going to try that. I was looking in the box that I received my lnb in. What is the fibreglass plate used for? I've never installed it.

it's for a power surge...hmmm

[sonicmario]

I'm going to try that. I was looking in the box that I received my lnb in. What is the fibreglass plate used for? I've never installed it.

its to convert linear signals to circular signals....

[dnasp002]

it's probably a flat scalar ring and is for maximizing signal quality and attenuating undesired interference

[sonicmario]

it's probably a flat scalar ring and is for maximizing signal quality and attenuating undesired interference

no its a Dielectric plate, Dielectric plates are used to convert linear polarized signals to circularly polarized signals.

[steveOtoo]

Dielectric plates are used to convert circularly polarised signals to linear polarisation. They work by utilising the difference in dielectric constant between fibreglass (or teflon) and air.28567

[sonicmario]

Dielectric plates are used to convert circularly polarised signals to linear polarisation. They work by utilising the difference in dielectric constant between fibreglass (or teflon) and air.28567

use that plate everyday on my 12 footer. works good for a few south american satellite 47W, 40W etc must be used to get signal... here in north america for C band it converts linear to circular....

[dnasp002]

no its a Dielectric plate, Dielectric plates are used to convert linear polarized signals to circularly polarized signals.

it's been a long time since I played with a c band dish, wasn't aware that they were even broadcasting circular

we used to do the same thing with some linear ku band lnbs but all we used was a piece of plastic

[lemme]

The emp comes from the high nearby voltage generating an emf in your coax that causes a voltage spike at both ends of the cable. I had this same problem but the gas surge suppressors worked for me. I have bought 3 chinese c band lnbs, and all 3 only work on 1 polarity. If your curious about building an emp cage it's called a faraday cage.

[dcapper]

I'm going to see if I can build something like posted. My dad just called and he lost Metv at home. But I'm sure it's just the dish is a little out of alignment. All the other channels work. I really need to hire someone to point his dishes.

[dcapper]

So I got the new lnb up at the lake but I can’t get some transponders. The ones that don’t work are of course and I the ones I want. 3725, 3733,3744, 3748, and 3764. The lnb manual says it works from 3.7ghz up to 4.2ghz. Low frequency 5150 and high 5750. Any tricks?

[sonicmario]

So I got the new lnb up at the lake but I can’t get some transponders. The ones that don’t work are of course and I the ones I want. 3725, 3733,3744, 3748, and 3764. The lnb manual says it works from 3.7ghz up to 4.2ghz. Low frequency 5150 and high 5750. Any tricks?

seems those are Vertical Transponders, can you confirm you are receiving any Vertical Transponders?

[dcapper]

You are right! I’m not getting any vertical transponders. Do I just need to rotate the lnb?

[sonicmario]

You are right! I’m not getting any vertical transponders. Do I just need to rotate the lnb?

what kind of lnb is it? does it receive both Horizontal and vertical polarities?

[dcapper]

It’s a cheap Chinese one but it should work.

[dcapper]

So I rotated the lnb and now I only get the vertical transponders. I’m using a Freesat V8 super. I either get a high signal on vertical or a high signal on horizontal. Am I missing something?

[sonicmario]

So I rotated the lnb and now I only get the vertical transponders. I’m using a Freesat V8 super. I either get a high signal on vertical or a high signal on horizontal. Am I missing something?

how many inputs on the lnbf im wondering if you need a switch to separate the 2 polarities?

[dcapper]

There is only the v hookup. The h is capped off. The dish was out a little bit but I think I got it better now but still no horizontal.

[sonicmario]

hrmm yea that is weird, when u go into the menu on ur reciever do you have your polarity set to auto? and lnb Freq set at 5150?

[dcapper]

Yup. My dad has the same problem at home. Only the verticals. It’s a titanium pll at his house and it was the same here until it blew. Now it’s this goldie cheap one. But there must be more to it. I’m at 42 on the focal point. I’m at 30 or so degrees turned.

[Terryl]

How does it specify on how to internally switch polarity's, by 13 or 18 volts DC ?? Or by 22 KHz on/off ??

13 volts DC equals vertical transponders, 18 volts DC equal horizontal transponders....You may have too low of a voltage drop out at the LNB that is out of spec, if the DC voltage is too low then all you will get is the vertical channels.

What type coax are you using and how long a run?

[sonicmario]

How does it specify on how to internally switch polarity's, by 13 or 18 volts DC ?? Or by 22 KHz on/off ??

13 volts DC equals vertical transponders, 18 volts DC equal horizontal transponders....You may have too low of a voltage drop out at the LNB that is out of spec, if the DC voltage is too low then all you will get is the vertical channels.

What type coax are you using and how long a run?

he says if he turns the lnb he will get horizontal only? and looking at the box it came in it does not really say much, thinking it may need a switch like you said.

[dcapper]

So get this. I changed the frequency from 5150 to 5750 and I get all the horizontal transponders but none on the vertical. I put it back to 5150 and only the verticals work. It must be the way the Freesat works. I’m going to see if I can add a satellite and then scan. Unless you have another idea?

[dcapper]

The run at the lake is pretty long but at my dads it’s maybe 40’. Both satellites have the same problem.

[Terryl]

I'd set it to a horizontal channel then go check the DC voltage out at the LNB's input, if under 17 volts DC you have found your problem, most DC switching LNB's have a 2 volt switching window, (horizontal =18 volts DC +- 1 volt) if it cant get above 16.9 volts DC it wont switch to horizontal.

And changing the LO frequency is not a good way to design an LNB as most satellite settings only have the one LO setting, unless its a universal or a dual band.(C and Ku)

The reason I'm asking about the coax is if the coax has a copper coated steel core it could be corroded/rusted somewhere along the line, this would cause a higher then normal voltage drop, I use coax with a pure copper center, less chance of a rust problem.

[dcapper]

It’s outdoor rg6 and it’s in a conduit with outdoor connectors. If I set it to 5750 is it going to blow the lnb? It’s a cheap lnb and I really don’t care. But at my dads house, it’s a short run and the same cable and connectors and it’s never worked on horizontal.

[dcapper]

I just looked the lnb box and it has a low of 5150 and a high of 5750.

[dcapper]

So I created a second satellite For the horizontal transponders and the channels are all working perfectly. Don’t ask me why 5750 is working with the horizontal transponders. My dad has the same Freesat V8 Super at home. I’ll try the same thing when I get to his house this week.

[jets]

DC two things. You channel is probably the high voltage and the drop on the 100 foot run is to much and it will not get the high voltage polarity.

On the other thing that you were blowing LNB's was that at Dads or another location? If at another location then maybe the LNB's are getting fried by the STB with the output voltage being to high? Just a thought.

[dcapper]

If anything I’m thinking the voltage was too low. The long run and the storms out here seem to be frequent. My buddy lost his bell lnb last year when I lost this lnb. The one with the short run has been great with no blown lnb’s but no horizontal either.

[Terryl]

It’s outdoor rg6 and it’s in a conduit with outdoor connectors. If I set it to 5750 is it going to blow the lnb? It’s a cheap lnb and I really don’t care. But at my dads house, it’s a short run and the same cable and connectors and it’s never worked on horizontal.OK.... RG-6 but is it the copper coated steel center conductor or the good stuff with the pure copper center?

Another over looked factor is the shield, the cheap stuff has a higher DC loss the the quad shielded stuff, I would as a test use RG-6 quad with a pure copper center rated out to 3 GHz, just run it on the ground (or however) as a tryout, this to see if the coax may or may not be the problem.

[dcapper]

He rg6 from from the local cable company. I used the same cable for both. The dish at my dads is a really short run too. I’m just wondering if these Freesats are not very good receivers. I cut a piece off and it’s copper all the way through. It’s working with the frequency change now. I do some more playing with it. What does everyone here use for receivers. Maybe I need to upgrade them.

[jets]

If anything I’m thinking the voltage was too low. The long run and the storms out here seem to be frequent. My buddy lost his bell lnb last year when I lost this lnb. The one with the short run has been great with no blown lnb’s but no horizontal either.

So if the voltage is too low you will lose one polarity. The short run is still missing a polarity then it could be crappy coax. You could make a break out cable and test the voltage at the LNB under load (connected). It's possible too that you are only getting the high voltage polarity and the STB is not switching it's voltage low enough. Measurement is the sure way to know.

Anyone know of a device meant to test voltage of a connected load?

[Terryl]

The coax for CATV is not rated for satellite work, it stops around 900 MHz, it may look like it works but some of the higher end transponders run up to 2 GHz. (after down/up conversion, LO frequency minus the "C" band transponder frequency) )

Do you have a small magnet?? If so try it on the center conductor of the piece you cut off, if it sticks it's CCS type of coax.

I can't quite wrap my head around why the two different LO frequency's work for different polarity's, something is goofy with that setup.(or LNB)

[Terryl]

So if the voltage is too low you will lose on polarity. The short rur is still missing a polarity then it could be crappy coax. You could make a break out cable and test the voltage at the LNB under load (connected). It's possible too that you are only getting the high voltage polarity and the STB is not switching it's voltage low enough. Measurement is the sure way to know.Not possible for an RF circuit like this, it will seriously up set the signals, you need a special interface to do a DC voltage measurement on an active RF circuit.

If he was getting only a high DC voltage then he would be stuck in the horizontal polarity's only, he gets the horizontal polarity's if he turns the LNB.

Plus 13 volts DC gets you the vertical transponders, plus 18 volts DC gets you the horizontal transponders, these voltages have a plus or minus 1 volt tolerance, if at the end of the run of coax your under 17 volts, the LNB may not switch correctly, if under 13 volts the LNB may stay in the default mode of vertical transponders only.

The average DC voltage drop on copper coated steel type center conductor coax is around 2.6 to 2.8 ohms per 100 feet, the average DC voltage drop on pure copper type center conductor is around .6 to .7 ohms per 100 feet.......What one would you all pick??

[sonicmario]

the run I have is around 150 feet, I was worried about RG6, so I went with the RG11 more expensive but worth it, could be an option for you dcapper, Amazon has a few sellers that offer it at a pretty good price...

[Terryl]

I use RG-11 in some of my long run installs, the only draw back is that the connectors are a bit hard to find, unless you get it with them installed.

[lemme]

Every chinese pos lnb I have tried will only work on one polarity. Their stuff is garbage.

[dcapper]

Bringing up the old thread. I'm still running 5150 for v and 5750 for h at the lake and it's still working fine. At my dad's house I took a portable tv and the freesat outside and used a 10' piece of coax and still no h. I'll change the lnb this week. But I know his signal gets weak a lot at the house. The neighbor parked his massive rv by the dish. I'm sure that's not helping matters.