Re: [Repeater-Builder] Re: Duplexer tuning with RF Power Change

[Doug Zastrow]

Skipp,   I want to make sure I've got this straight in my head...   For the final tweak on the transmit side bandpass setting I would:   A)  Look for minimum reflected power from the duplexer 'xmt' port back to towards the transmitter.   B)  And then I'd also look for maximum forward out of the duplexer 'ant' port towards the antenna.   I suppose the wattmeters could cause some interaction that would change things when removed....   Am I close?     Doug ----- Original Message ----- From: skipp025 To: Repeater-Builder@yahoogroups.com Sent: Thursday, December 22, 2005 11:16 AM Subject: [Repeater-Builder] Re: Duplexer tuning with RF Power Change Hi Gary, It's not exclusively related to the Loaded and Unloaded Q of the Cavity. Cavities do get warm under extreme conditions, but I've yet to feel a typical two-way radio cavity rise more than warm to the touch in high power pager type operation. I have seen some "small cavity" mfgrs place hefty heat sinks on the high current end of a cavity... but none of the mfgrs has actually offered up the honest technical reason why they use them. I once heated my lunch on a multi section tx band pass cavity used by KFOG FM in San Francisco (Sutro Tower Site). The high current end of the cavity would almost boil water during normal high power fm broadcast operation... Was very impressive... Back to square one of the topic. One can set up a band pass cavity using a service monitor. The final tx side BP Cavity adjustments should be checked with a watt meter (or two) included... under actual rf power. cheers, skipp > [EMAIL PROTECTED]... wrote: > Skipp.....Thank you for the info on duplexer tuning with > RF power  change.  Interesting. Maybe expansion of the > actual can due to heat vs Invar  rods? > Gary   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  Visit your group "Repeater-Builder" on the web.    To unsubscribe from this group, send an email to:  [EMAIL PROTECTED]    Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.