Extend LNB cable?

Acid0

Acid0

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Hi there,

there is a thread that was in 2011 but I dont want to resurrect an old thread.

How far can you extend the LNB cable?
The house and the flat on the property is quite a distance from each other.
So I was thinking of having the dish on the main house and then just extend the LNB cable from the dish/decoder to the flat.

Do I need some signal booster or can I actually just extend a normal LNB(coaxil) cable to the flat staright from the main house.

I know the CAT6 can extend to about 600m without any boosters, so would I need a special cable to do the LNB extension or not.
 
RG6u coaxial can have a length of 300m without significant signal degradation. If it was me I wouldn't need a signal booster unless the flat is that far out from the dish/house
 
stepper said:
RG6u coaxial can have a length of 300m without significant signal degradation. If it was me I wouldn't need a signal booster unless the flat is that far out from the dish/house
Click to expand...

No. Just no.

RG6 is some of the poorest coaxial cable around. Some specs I found specifies a loss of 32.5dB/100m at 2.4GHz. DSTV operates around 11/12GHz, and cable loss increases with frequency. Just for reference, let's say the loss is 30dB/100m. That means that for a 100m cable, only 1/1000th of the power reaches the end of the cable.

So cable length plays a massive role in the power received by the receiver.
 
AntennaMan said:
No. Just no.

RG6 is some of the poorest coaxial cable around. Some specs I found specifies a loss of 32.5dB/100m at 2.4GHz. DSTV operates around 11/12GHz, and cable loss increases with frequency. Just for reference, let's say the loss is 30dB/100m. That means that for a 100m cable, only 1/1000th of the power reaches the end of the cable.

So cable length plays a massive role in the power received by the receiver.
Click to expand...

So what would be the suggestion then?
 
So, how far do you want to actually run the cable... and what decoder is on the other end of the cable?
 
AntennaMan said:
No. Just no.

RG6 is some of the poorest coaxial cable around. Some specs I found specifies a loss of 32.5dB/100m at 2.4GHz. DSTV operates around 11/12GHz, and cable loss increases with frequency. Just for reference, let's say the loss is 30dB/100m. That means that for a 100m cable, only 1/1000th of the power reaches the end of the cable.

So cable length plays a massive role in the power received by the receiver.
Click to expand...

No. Just no.

The broadcast signal is at 10970 - 11674 MHz. After the LNB, on the cable, it sits at 1220 - 1924 MHz. The LO of the LNB is 9750, which is how much the LNB drops the low band frequencies before sending it to the output.
 
Acid0 said:
Hi there,

there is a thread that was in 2011 but I dont want to resurrect an old thread.

How far can you extend the LNB cable?
The house and the flat on the property is quite a distance from each other.
So I was thinking of having the dish on the main house and then just extend the LNB cable from the dish/decoder to the flat.

Do I need some signal booster or can I actually just extend a normal LNB(coaxil) cable to the flat staright from the main house.

I know the CAT6 can extend to about 600m without any boosters, so would I need a special cable to do the LNB extension or not.
Click to expand...


The issue is why do you want to rely on one antenna at all if you are going to install decoders in both locations?

Others have shown why it is not a good idea already, so I am simply going to add some additional thoughts.

The absolute best answer is 2 antennas one at each location. Best performance and best signals levels under bad weather conditions. Signal amplifiers, boosters, call them what you like are not ideal and are certainly second prize when it comes to trying to receive HD channels.

The other reason for avoiding this type of installation is related to surge and lightning protection. There is just about no way you will be able to limit/eliminate earth currents flowing between the two installations via such a long RF feed. Really bad news given the sensitivity of the electronics involved.

Save yourself the cable costs and the amplifier costs by simply comparing the combined cost with the cost of another antenna and LNB.
 
stepper said:
RG6u coaxial can have a length of 300m without significant signal degradation. If it was me I wouldn't need a signal booster unless the flat is that far out from the dish/house
Click to expand...

I suggest you relook at the typical attenuation figures for RG6 cable. What you say is not correct .
 
AntennaMan said:
No. Just no.

RG6 is some of the poorest coaxial cable around. Some specs I found specifies a loss of 32.5dB/100m at 2.4GHz. DSTV operates around 11/12GHz, and cable loss increases with frequency. Just for reference, let's say the loss is 30dB/100m. That means that for a 100m cable, only 1/1000th of the power reaches the end of the cable.

So cable length plays a massive role in the power received by the receiver.
Click to expand...

The basics of your comment are correct, but you have forgotten that there is a down conversion process taking place in the LNB, which means the IF frequencies are much lower.

Even so, the range of frequencies as shown by Quantum Theory's post are at the top end of the range covered by RG6 cables, with the greatest losses.
 
Last edited:
Quantum Theory said:
No. Just no.

The broadcast signal is at 10970 - 11674 MHz. After the LNB, on the cable, it sits at 1220 - 1924 MHz. The LO of the LNB is 9750, which is how much the LNB drops the low band frequencies before sending it to the output.
Click to expand...

daniellgr said:
The basics of your comment are correct, but you have forgotten that there is a down conversion process taking place in the LNB, which means the IF frequencies are much lower.

Even so, the range of frequencies as shown by Quantum Theories post are at the top end of the range covered by RG6 cables, with the greatest losses.
Click to expand...

You are both correct, I missed the down conversion. The attenuation at 1GHz and 2 GHz is around 20dB/100m and around 25dB/100m respectively. That is still 60 - 75 dB of loss in 300m of cable.
 
Actually both dainellgr and AntennaMan are correct for signal distribution from LNB.
My assumption was it's for video distribution from the decoder (RF out)
 
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