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Hi all, This topic is very well described in an article (on Kevin's website) by
Jacques Audet VE2AZX. It is a large file but well worth the time
downloading. You will find an excellent explanation of the various types
of duplexers in which, at the end, he recommends this discussed configuration
as the best combination of cavities to form a good duplexer. Go to this link http://www.repeater-builder.com/rbtip/ant-sys-index.html And scroll down to the article in PDF format
73, Tony VE3DWI ************************************************** > Eric Lemmon WB6FLY gave the best response to my > question of "how > common is it to place a bandpass fillter betweeen > antenna and > duplexer. Most assumed a ham repeater with tx > circulator and high > rejection pass/reject duplexer which is correct. > > About 25 years ago I had Wacom retrofit a 4 cavity bp/br 2 meter duplexer with two pass cavities. One for the receive side to provide out of band rejection and one on the transmitt side to make it ballanced looking if for nothing else. The repeater was in an area with lots of other transmitters near it. Must have been over 100 antennas in a 3 block area. Later I noticed they were offering that design in their catalog. Seems most bp/br duplexers do not really have taht much rejection of out of band signals. ____________________________________________________ Start your day with Yahoo! - make it your home page http://www.yahoo.com/r/hs 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/ YAHOO! GROUPS LINKS
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This is a large (60 pages) technical write-up
that should be titled "Duplexers 101". Well worth reading.
