On Wed, 20 May 2009, Eric Lemmon wrote: > I think we've found the cause of your desense: The TPRD-1454 > duplexer, which has four 5" cans, is rated at 77 dB isolation, and is > marginal with 20 watts TX and RX sensitivity of 0.4 uV- which calls > for at least 82 dB isolation. At 100 watts, 95 dB is recommended. > While these recommended figures are ballpark estimates, they have been > found to be quite realistic. > > If you were using a tube-type PA, you might get by with your duplexer, > but a solid-state PA needs more isolation. At 600 kHz separation, a > duplexer with four 8" cans or six 5" cans is the norm, and even more > is better. Even when tuned on a network analyzer, a TPRD-1454 > duplexer seldom can reach 80 dB- and that is simply not enough.
Not to mention the LMR :-p -- Kris Kirby, KE4AHR Disinformation Analyst
