duplexers

bayfire300 · Post by **bayfire300** » Sun Oct 16, 2005 1:08 pm

whats the difference between 4 cavity and 6 cavity?.....does it make a difference in performance? i am speakin about mobile duplexers.
i need another 1 and and i saw 1 on e-bay but it is 4 cavity.

thanks
otto

Will · Post by **Will** » Sun Oct 16, 2005 3:37 pm

Yes it does. The extra cavity in each side adds filtering increasing the isolation of the TX and RX. A 4 'cavity' UHF duplexer mite have 60db isolation where as a 6 'cavity' would have 80 db isolation. (depending on the model and Mfgr.)

You can find more revelevent information in the System and Infastructure Fourm here on the BatBoard and at http://www.repeater-builder.com

bernie · Post by **bernie** » Mon Oct 17, 2005 8:52 pm

My two bits worth:
As Will says the more cells, the more isolation.

The 4 section unit would find application in a very low power situation such as a mobile telephone.

Beware that the terminals might be labled Rx & TX, which would be for a mobile telephone. What is important is HI and LOW frequency.

EKLB · Post by **EKLB** » Tue Oct 18, 2005 3:21 am

bayfire300 · Post by **bayfire300** » Tue Oct 18, 2005 9:32 am

eklb where are you located and how much are you askin for the duplexer.....i need one w/ n connectors
otto

oh and by the way i managed to find 1 inch andrews heliax for 50 bucks 100 foot....i posted the story on the other thrad ..rg-8 or lmr-400

bernie · Post by **bernie** » Tue Oct 18, 2005 9:38 am

My two bits worth:
If you read the specs on the GR300/500 repeater "Not for conjested sites"
The notch only duplexer is small, and cheap.
A decent pass/reject duplexer is roughly the size of the entire GR500 station.
All of these devices have their application.