Signal strength over a long cable run

L

luffy m

Member
My Satellite Setup
2 sky+ and one Sky hd with a 1m dish situated 100m away
My Location
East Yorkshire
Please feel free to move this thread if I have posted in the wrong place. Having read through the posts on the forum I see there is a wealth of knowledge here but not many recent posts about my issue so thought i would check to see if anything has improved.

I have a 1.2m dish with 8 output lnb and have tested the signal output at the lnb and it is pretty much bang on in terms of alignment and strength.

this is then fed through 100m of copper/copper cable back to the house where it feeds into 2 sky+ boxes and and a sky hd box. The 2 sky+ boxes work ok and the signal is significantly degraded but the sky HD box struggles with the poor signal. It is the original HD box but i have replaced the power card in the box which has solved all the other problems.

Can anyone please recommend an inline amplifier to boost the signal down the line? I want to explore this option first before upgrading the cable since i do not want to buy 600m of more expensive cable. Moving the dish closer to the house is not an option. 100m is as close as I can get.

If anyone has another solution then i am welcome to suggestions as fed up with always having channels missing.

cheers
 
Triax IF slope compensator amplifier, 12dB gain with adjustable slope control. Ref: 370650

Ideally best set with a spectrum.
 

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With that distance of cable, a line amp inserted in each run at about 50m from the LNB should solve the problem, cheap and easy to do.
 
luffy m said:
If anyone has another solution then i am welcome to suggestions as fed up with always having channels missing.

cheers
Click to expand...

Using a Optic fibre LNB, and a single fibre optic cable would be a another solution, but more expensive than amps.
 
Yes, Fibre Optic certainly would be the only way to go if starting from scratch and the dish could be reverted to a standard size, say 80cm.
 
Thanks for the advice gents, Greatly appreciated!

I will try the line am solution on the HD feeds first and see if that helps.

I am interested in the 80cm dish fibre lnb and fibre cable idea though as getting rid of some of the cables does appeal. Couple of quick thoughts if I may?
How would I then split the signal out to the 6 feeds once I reached the house.
I'm guessing the signal strength and quality would be much better as there would ne nearly no degradation over the 100m cable run.
How is the lnb powered? will I need to run a 100m powercable back to the dish?

thanks for your help
 
Sorry, forgot to add. from looking through earlier reports i have seen conflicting advice as to whether to place the amp near the lnb or to break the line halfway and place it there.

does anyone have any advice regarding this. I am intending to try at the lnb firstas i can easily revert although if i break the cable i am committed.

thanks

m
 
_http://shop.satelliteonline.co.uk/satellite-distribution-81-c.asp

a rough idea of how much these systems cost.

The LNB would need a DC power supply, that could be quite tricky to deliver over 100m but the signal from the fibre optic system would be fantastic.
 
No problem with the power supply for the unit, as there are already coax runs there, one of these can be used, exactly what I did on my last fibre installation, although that was WF125.

Regarding the signal strength, there is no real loss, if you are achieving an average of mid seventies in dbs at the dish, that's pretty much what you will get at the other end, so just use a virtual quattro converter then a six or eight way multiswitch. Job done.

Still cheaper in this case to use the existing cables and line amps. The reason I would fit these some distance from the 1.2m dish, is that they will have a maximum handling figure and a 1.2m dish may exceed that figure if the amp is immediately down line from it.
 
This forum is a great resource!

I'd never heard of quattro lnb's before and if I have understood this correctly then i can change the octo lnb to a Quattro and then just run 4 cables down from the dish and then plug them into a multiswitch where the coax comes into the house. From the multiswitch I can then split the signal out to the three sky boxes in the house.

Am I correct in thinking that by running the Quattro this should eliminate the need to use inline amplifiers? sorry for the dumb questions but i want to make sure i get this right this time as i've spent a few quid already and dont want to waste any more.

thanks again
 
No, you would still need some preamplification to account for the losses over a 100Mtr run, but can still be line powered.

Check the specification / maximum output of any line amps, as they could be overdriven, mentioned above. The higher, the better and can be placed closer to the dish in order to maintain a good SNR.
 
So there is no real beneft to moving to the quattro / lnb solution then as it isnt going to do anything more than if I inline amplify the existing 6 lines as I would have to do the same with the four lines fed from the quattro plus buy the lnb and a multiswitch?
 
luffy m said:
I have a 1.2m dish with 8 output lnb and have tested the signal output at the lnb and it is pretty much bang on in terms of alignment and strength.

this is then fed through 100m of copper/copper cable back to the house where it feeds into 2 sky+ boxes and and a sky hd box. The 2 sky+ boxes work ok and the signal is significantly degraded but the sky HD box struggles with the poor signal.
Click to expand...

It is a pity that there is no Inverto Black Ultra Octo as the higher conversion gain output would probably cure the problem. :(

You don't say what LNB you have, but older LNBs often output around 50dB, more recent ones around 55dB. The Black Ultra at 60dB would provide +5 to +10dB and also have less noise.

Hopefully they will produce an octo soon, there is a growing market for it.
 
Being able to read the signal in dBuV would be an advantage, but understand that hobbyists do not have such measuring equipment. As we do not know the signal level from the dish [although I have a pretty good idea] and you may not be able to find out the max o/putput of any such pre-amps; go for them at the front end first if you wish and see. Ideally place them 30 - 40Mts down the line as mentioned somewhere previously in the thread.
 
I have a satfinder3 and think that this does give a readout in dBuv so can check the signal strength when I get it back. Thanks for the advice, much appreciated!!
 
and sorry, the lnb is the Inverto Pro 0.2dB Octo LNB
 
I have an almost 80m run made up of 3 old RG6 cables connected with an f - f connector, plus the 2-3dB insertion loss of the motor, which delivers the signals from 28e (plus the other strong satellites and the old 16e) from a dish almost 50cm smaller and a cheap LNB of similar gain.

So I find it hard to believe that the cable length is really the problem.

Some of my cable is almost 20 years old. Only the short bit from the LNB to the motor is 'new' :o

Is the dish being shadowed by something, are the cable connections good, is the LNB below par, there could be a number of things wrong.
 
I have used unbroken copper/copper cable and used a scaffolding post that is solidly concreted to the ground and is vertical. When i installed everything i was a little disappointed with the signal strength so called in a professional installer to check my work and ensure i hadn't made any glaring errors and they tested the alignment of the dish which they found to be as good as he could get. he also checked my terminations and found no faults there. I welcome any suggestions anyone may have as this issue has been driving me nuts.
 
The first thing I's try is to measure the resistance of all the cabling and see if any are higher than the others.

A few years ago I had an entire roll of 100m cheap coax hung off my 60cm Sky dish and didnt see any appreciable drop in signal strength on any of the frequencies I looked at. (just using the receiver meters - I dont have any specialised gear.

To be honest you are probably better off going down the fibre optic lnb solution - no signal loss over km of cable. Its an expensive solution but if you want decent signals....


Sat Europa sell them

-http://www.sateuropa.co.uk/overview.asp?catid=12&subcat=66
 
luffy m said:
The 2 sky+ boxes work ok and the signal is significantly degraded but the sky HD box struggles with the poor signal. It is the original HD box but i have replaced the power card in the box which has solved all the other problems.
Click to expand...

If the other Sky boxes are ok, it sounds like the Sky HD box has a crap tuner as well as a crap power supply. I don't think you can source a replacement tuner as easily as the power module.

Perhaps install amplifiers only on the 2 cables to the HD box.

Unless the HD box has other problems - in which case replace the box.

You coud swap the connections for the Sky HD box to the 2 spare on the LNB, but I expect you have tried that already. If there is an improvement, leave it there! Or get a replacement LNB under warranty.

Also, are you using self-amalgamating tape on the LNB connections? Winter storms can blow water under the plastic skirt and it can then freeze when it gets colder.

Are there tight bends in the cable, they have a minimum bend radius.
 
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