Bernie, When you put the Bird between the TX and the duplexer, you have changed the length of the jumper cable, which upset the tuning. But, really, you need not worry about what the SWR is, if the forward power to the antenna is appropriate.
Let's say you have a 4-can duplexer, which might have about 1.5 dB insertion loss. If your power amp delivers exactly 100 watts into a dummy load when connected directly at the TX output, you should expect about 70 watts going to the antenna when the duplexer is in the circuit. A 6-can duplexer might have about 2.2 dB insertion loss, and you should see about 59 watts going to the antenna. 73, Eric Lemmon WB6FLY -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of dallasreact112 Sent: Friday, August 24, 2007 5:16 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Duplexers Anyone one know what to expect SWR wise with a duplexer? I have a DB products 2 meter duplexer on an amateur repeater. Measuring with a Bird wattmeter between the duplexer and antenna I read 50W forward and a couple watts reverse. That is ok. But when I check between the transmitter and the TX port on the duplexer I get a about 60 W forward and 25W reverse power. Is there a rule fo thumb for a known good SWR value thru a duplexer? Should a good duplexer introduce any significant SWR? Thanks Bernie Parker K5BP
