Like Ken said; all 3 ports need to be terminated in 50 ohms when tuning. A signal generator is usually fairly close to 50 ohms, a receiver may or may not be, usually not. The unused port at the time needs a 50 ohm load. The best way is to use a 6 db pad on gen and rec sides while tuning.
But what may be the worst problem is you may be trying to use it too far from the design frequency. You have no way to tune the loops on those units. Also be sure you haven't reversed the tx and rx frequencies as the loops are tuned internally to pass a frequency only on one side of the notch. 73 Gary K4FMX > -----Original Message----- > From: Repeater-Builder@yahoogroups.com [mailto:Repeater- > [EMAIL PROTECTED] On Behalf Of fxbuilder > Sent: Tuesday, February 20, 2007 9:49 AM > To: Repeater-Builder@yahoogroups.com > Subject: [Repeater-Builder] Re: Band Pass Duplexer Tuning > > Ok... So I've tuned this duplexer as a notch device. Put a 2 watt > handheld into a dummy load and watt meter (not in that order mind you) > and it seems to reject the corresponding frequencies. My question now > is... Why did my swr jump from 1:1.3 to 1:3. Do I need to re-tweek > it? Also I'm noticing a huge power loss when measured before and > after the duplexer. Talking 30 watts down to below 10 watts. Any > suggestions. Perhaps it is time to check the cables etc? Thanks for > all the help in the past. > Craig > > > > > > --- In Repeater-Builder@yahoogroups.com, "Gary Schafer" > <[EMAIL PROTECTED]> wrote: > > > > Lots of the small mobile duplexers (notch type) have fixed > capacitors inside > > and you can only adjust the cavity tuning, which tunes the notch. > > > > This type duplexer is limited in how far from the design frequency > you can > > tune it as the capacitors are fixed. The cavities will tune but the loss > > goes. > > > > 73 > > Gary K4FMX > > > > > -----Original Message----- > > > From: Repeater-Builder@yahoogroups.com [mailto:Repeater- > > > [EMAIL PROTECTED] On Behalf Of fxbuilder > > > Sent: Friday, February 16, 2007 5:09 PM > > > To: Repeater-Builder@yahoogroups.com > > > Subject: [Repeater-Builder] Re: Band Pass Duplexer Tuning > > > > > > I emailed the place I bought it from and that is what I was told. > > > Band Pass. No caps on it for notch tuning as on celwave. Am I missing > > > something here? > > > Craig > > > > > > > > > > > > > > > --- In Repeater-Builder@yahoogroups.com, Ken Arck <ah6le@> wrote: > > > > > > > > At 01:53 PM 2/16/2007, you wrote: > > > > > > > > >There is a great article on this site about tuning a notch > duplexer by > > > > >Kevin. Can similar methods be used for tuning a mobile 6 can band > > > > >pass duplexer? Is there an article that I missed that explains > it as > > > > >easily? I need to re-tune and could use the help. I think I > know how > > > > >but thought I'd check. > > > > > > > > <----Is there such a thing??? > > > > > > > > Ken > > > > > > > > -------------------------------------------------------------------------- > > > ---- > > > > President and CTO - Arcom Communications > > > > Makers of the world famous RC210 Repeater Controller and > accessories. > > > > http://www.arcomcontrollers.com/ > > > > Authorized Dealers for Kenwood and Telewave and > > > > we offer complete repeater packages! > > > > AH6LE/R - IRLP Node 3000 > > > > http://www.irlp.net > > > > > > > > > > > > > > > > > > > > > > > > > > > > Yahoo! Groups Links > > > > > > > > > > > > > > > > > > > Yahoo! Groups Links > > >
