I have a Drake TR-7 with the second version of the NB-7 noise blanker
(not the nb-7a). It is not very good at blanking out noise. The
noise blanker on my Cobra 148 NW ST (cb radio) is far superior at
blanking power line noise. Are their any known modifications for
improving the Drake NB-7 noise blanker or any replacements for the
NB-7 noise blanker?

Michael Rawls