At 9/8/2010 18:24, you wrote: >At 06:18 PM 9/8/2010, Richard Kelly wrote: > > > > > > We will be trying other things such as adding a second ground rod > > outside the shack instead of the single one we use now. We will > > also try isolating the amp some more and replacing the coax feed > > line with hard line. > > ><--That is a complete waste of time as that is not the problem. Your >duplexer simply cannot provide enough isolation for the power level >you're trying to run. > >More grounding and replacing coax with hardline (unless your coax >isn't doubleshield to start with) will buy you nothing.
Replacing copper-braided coax with RG-214 or hardline is hardly a waste of time. The duplexer isolation may not be quite enough, but that can be easily remedied by adding an extra pass cavity to the TX. Just another 10 to 15 dB of TX noise suppression is likely all you need. RG-8, RG-213 or LMR-400 antenna feed, OTOH, will make any duplexer moot due to all the desense it will generate, sooner or later. Bob NO6B
