Evaluation Of In Line Amplifier

Tivù

Being one of those who always advocates the theoretical line whenever Satellite IF Amplifiers come up on forum, yet also being aware that the practical experiences of some don't, on the face of it, match the Theory, I forked out 3 Yorkshire Groats for a Chinese made 13-18dB Amplifier from Ebay to play with.

Recap: The Theory is that despite low noise components being the norm nowadays, the Amplifiers will add a modicum of Noise of their own, so can only really be used to compensate for losses on long cable runs. They can only attempt to recover a little of what was already there and was lost.

What they cannot do is compensate for the absence of signal at source. Only a bigger Dish can achieve that. (We are still talking Theoretically here - I have read the reports from others both here and elsewhere which seem to gainsay the theory .........)

The Tests: Fitted this at various places along the cabling to my 1.1m Motorised Dish. ie At the LNB, At the Motor, At the Receiver.

The Constraints: My cable run is not "long", being less than 10m.

The Results: Sadly, the theory is fully borne out. The device passes power and Motor Control signals as promised. The Signal Strength on weaker but stable TPs went up eg from 60 to 70, from 70 to 80 etc. Quality was scarcely affected.

A Couple Of Anomalies:

1. Where a TP was marginal on Quality, the Amplifier effectively blocked it (Not a dicky-bird)! This occurred consistently and I eliminated "finger trouble" on my part.

2. Transferring the Amplifier to my 80cm Motorised Dish threw up similar trends except the Signal Strength went down by 10 points or so!

After some head-scratching, I swopped my Receivers around and discovered that my Kaon behaved as you'd expect and showed the desired increase in indicated Strength. But the Silvercrest SL65 seemed to register a decrease which I put down to over eager AGC.

That conclusion, whilst possibly wrong, is reinforced by the fact that the massively strong TPs from various Satellites especially Astra 2 and Atlantic Bird 3 indicate relatively low Strengths on the Silvercrest, though moderate TPs seem ok. The Kaon again behaves as you'd expect if attached to the same Dish etc.

So I've proved very little but had a decent few hours fa**ying about!

Anybody need a cheap Amplifier?

teach

Hi Tivù
Some good pontificating has taken place here, and it just goes to show that you can't get what isn't there in the first place. just like the old saying " you cant get water if the well is dry"
thanks for sharing your findings.

Teach

Tivù

You're welcome.

There's nothing like a good spot of pontification!

But the exercise was for reference next time it is suggested that such a device might alleviate fringe reception problems (as I suspect you correctly surmised)

satelliteman

The Slope Compensator Amps are fairly good. Adjustable gain line amplifier with a slope control.

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Robbo

Very useful test.

Though, annomaly 1, not really one by itself, as, as you say, the amp adds noise to the system and will thus reduce the resultant SNR causing probs where it was barely sufficient in the first place.

Good to know that motor signal etc pass through OK.

BombedOne

As I have tested before (and reported on this forum), On average receiver, average in-line amplifier gives about 10% increase in Q.

SL65 is really very bad receiver, I also have it and it's sensitivity is one of worst ones I ever seen. Also, it's very critical to LNB.