Hamtronics has a preamp with a helical resonator with a 18dB preamp. I am at a high elevation with noise all around me. Advanced R3esearch has a 24dB preamp with a low NF and 1dB compression point. Either would be behind a WACOM 642 6 cavity duplxer.
Which would be the better approach? The ultimate goal is to improve reception of handhelds in a mountainous region.