As Eric points out, this duplexer doesn't provide a lot of isolation. Usually 90+ dB is required and more is often necessary, depending on several factors like the actual receiver sensitivity, using a preamp and how good it is, and the actual transmitter power level, spectral purity of it, and actual site conditions.
That being said, this duplexer would perform very satisfactorily on a GE Mastr II 2 meter repeater (600 kHz) running 100 watts utilizing a PLL exciter, and possibly a preamp. The GE PLL exciter exhibits about 22 dB less transmitter sideband noise than does a typical multiplier exciter, and that 22 dB doesn't need to be made up for in the duplexer. Many preamps should not be hit any harder than about -40 to -50 with shear power or, with other out of band sources present, will be driven into the non-linear region. Considering 100 watts of power into the duplexer, about 70 watts would appear at the antenna port, or a level of +48 dBm. Now take the 48 dBm and reduce it by 77 dB and -29 dB results. At neg 29, the stock GE Mastr II UHS preamp would likely work as the measured noise figure & 1 dB output gain compression point are 4.6 dB & +1 dBm, respectively. Considering a gain of around 12 dB and assuming your VHF preamp performed similarly, you'd get -17 dBm of TX signal at the preamp output, 18 dB below the +1 dB GCP. While it would work, it won't be able to handle much more signal from any other sources. This duplexer could work well at a unpopulated site using (the above suggested) solid state equipment at typical levels (100 watts); with decent receiver sensitivity (-122 dBm for 12 dB sinad). Kevin Custer Eric Lemmon wrote: > >Mark, > >The TPRD-1454 is not a bandpass duplexer; it is a bandpass/bandreject >duplexer- quite a different animal. With a 600 kHz isolation of 77 dB, it >should perform satisfactorily on 2m with a tube-type PA. The data sheet is >here: >http://www.telewave.com/pdf/TWDS-6025.pdf > >73, Eric Lemmon WB6FLY > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
