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Satellite Inline Preamplifier

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lew247

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Can anyone identify the components circled in yellow on this picture please?
it's an inline satellite preamp but the noise figure is over 5db
I want to replace the active components with more modern ones with lower noise - is this possible?
any suggestions?
 

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I have an 80M run of cable to the dish, thats why I need an inline one
I want to improve the noise figure, as they actually dont help at all when in, in fact I'd say they slightly degrade the signal
I can't move the dish any closer, or make the cable run any shorter or put up a larger dish, all of which would help
 
I have an 80M run of cable to the dish, thats why I need an inline one
I want to improve the noise figure, as they actually dont help at all when in, in fact I'd say they slightly degrade the signal
I can't move the dish any closer, or make the cable run any shorter or put up a larger dish, all of which would help

The noise figure doesn't really matter, as it's only an IF amplifier, so the signal is at a relatively high level anyway.

Where the noise figure matters is in the front end of the LNB.

If the amplifier isn't helping (compared with removing it), then it's faulty and needs repair or replacing - replacing with a modern 'better' one is probably the easiest solution anyway.
 
I agree, thats why I wanted to know if anyone recognised the semiconductors on the picture so I can replace them with better ones
It's almost impossible to find a low noise inline amp for satellite - they all seem to be around 5db noise figure
I have several low noise preamps for radio use which are a lot lower noise, I did consider modifying one or two of them to see how they'd work, it wll be easy enough to power it from 12/18v instead of the 5v it has now, its feeding that 12/18v through to the lnb that I'd have trouble working out
I would imagine its as simple as making sure there is a dc blocking capacitor on both ends of the preamp and using an inductor to feed the power
But I've no idea what value inductor to try - especially as it would have to let the 22Khz switching through as well
 
I agree, thats why I wanted to know if anyone recognised the semiconductors on the picture so I can replace them with better ones
It's almost impossible to find a low noise inline amp for satellite - they all seem to be around 5db noise figure

I'm a bit confused what you agree with? :D

I said you don't need a lower noise figure for an in-line preamp, as it works at relatively high level IF frequencies.

What problems are you getting?, I'm presuming it's a digital satellite system?.
 
I meant I agree with "Where the noise figure matters is in the front end of the LNB"
I know the IF is 950Mhz to appx 2200Mhz but with a 5db noise level in the inline amplifier, its degrading the signal instead of improving it, which is why I want a low noise inline amplifier
Its digital satellite, Astra which is a strong enough signal even with the 50cm dish, the problem is the long length of coax going to the receiver
The symptoms are breakup when it rains, and if its a storm it goes altogether
The dish is aligned properly, and I cant put a bigger one up
 
I doubt that a lower noise amp will solve that problem.
 
Considering how strong Astra is in the UK, and its the cable length that makes the problem, a low noise inline amplifier about 10M from the dish should help it as it will overcome the losses in the cable
 
I meant I agree with "Where the noise figure matters is in the front end of the LNB"
I know the IF is 950Mhz to appx 2200Mhz but with a 5db noise level in the inline amplifier, its degrading the signal instead of improving it, which is why I want a low noise inline amplifier
Its digital satellite, Astra which is a strong enough signal even with the 50cm dish, the problem is the long length of coax going to the receiver
The symptoms are breakup when it rains, and if its a storm it goes altogether
The dish is aligned properly, and I cant put a bigger one up

If the amplifier is degrading the signal then it's faulty - as I've repeatedly said, it's at IF frequencies (and signal strength) so the noise factor isn't any concern, that ceased to be a worry after the first RF amp in the LNB.

Presumably you have the amplifier near the dish, and not at the bottom end?.

Are you using proper WF100 cable?, 80m would probably be fine without an amplifier anyway, as Astra (presumably Astra2?) is incredibly strong in the UK - back in the Astra 1 analogue days I tried running through a full 250m drum of cable, and it still worked perfectly.

What are the on-screen signal strength/quality readings?, I'm presuming you don't have a Digital Satellite meter?.

More likely reasons would be poor alignment (has it been aligned at the dish with a proper digital meter, including skew), a duff LNB, faulty cable (or water in the cable), or a deformed dish.
 
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