Signal boosters

[Cascade]

I replaced my ageing DirecTV cable with a fresh run of RG6 and a new set of LNB cables (Thanks, P) to see if I could get a better signal to my receiver on some of these birds, AMC4 and 1 especially.
My cable run is around 100ft with a ground block splice where it enters the house.
I know I have a major problem with trees and I thought i'd try an inline amp to make up for the cable loss so I bought an amp from Lowes supposedly giving me 13dB gain over 950-2200MHz.
I notice that when I plug the amp in, my signal level drops, I measured it on AMC2 whilst tuned to the compelling "Congratulations/superdish/etc" channel, when running without the amp I have a signal of 33% and Q of 100% - with the amp it's dropping to 25/100.

I have it setup like this..

LNB1/2-Diseqc switch-Motor-Amp-----------100ftRG6-----------Receiver.

Are these amps a waste of cash? I know I have it plugged in the right way but it just seems to attenuate everything.

Cheers all.

 

[PSB]

Those things only help if you have REALLY long runs, I just done a servive call the guy had a very bad signal as the first installer put the dish under the overhang of his roof, they were actully making his signal worse! I removed them and the signal took a jump, I also had to work on the over hang issue, but they were not helping the signal! Amps will not help if you have a bad/low signal to start with, time to move to the desert : )