My first amplifier which I purchased 2 years ago, was unbranded, and frequency range 47 - 2400 MHz.
When I installed it, I ended up in same problem as you.
I removed it from my system.
My second amplifier, which I purchased 2 years ago (shortly after first one), was branded (RCA D903) and I got excellent results.
Nine months ago I found an amplifier on eBay, unbranded, frequency range 950-2150 MHz, and exactly like yours, for Canadian $3.66 + Free shipping from China.
Allured by price, I ordered it.
When it arrived, I replaced RCA D903 by the new unbranded one, and my system collapsed!
I removed unbranded amp, and and put back RCA amp.
I threw both unbranded amplifiers in garbage, and lived happily ever after 
.