[UK-CONTEST] RX antenna pre-amp

[G3SJJ]

Just completed a Coax Rx Loop antenna for 160m. It works well but would 
benefit from some extra RF gain.

I have assembled a little TenTec Broadband RF Pre-amp kit No 1001 in an 
ali box but having probs. I suspect it may be taking off. Switching it 
in the band noise goes up to 25db over s9 and drowns out the signal. 
Voltage on the MAV1-0104  is 5V. I've put my Dunestar 600 filter  
between the loop and the input front but it doesn't help much. I have 
W3LPL rx bandpass filters under construction but will take some time to 
complete. At present haven't screened the input /output leads from the 
BNC connectors to the PCB, they are about 8cms long. Anyone got any 
experience of this amp and how I might tame it?

Chris G3SJJ