Gary, When selecting a duplexer you want a model that is speced for the same TX - RX spacing as the application or less. Operating a 500K spacing duplexer at 600K is not a problem but trying to get a 1M spaced duplexer to operate at 600K will be. The issue is the way the individual pass/notch filters interact with each other. If you can get a copy of a Telewave catalog they have a nice section in the back that gives plenty of information about filters and duplexers.
As to your immediate problem, adding a pass can via the proper length of coax on the RX side may help. I would suggest that you look for someone in your region with the proper test equipment to sweep tune the equipment. Also what type of repeater equipment are you using? Milt N3LTQ ----- Original Message ----- From: "garyp609" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Friday, July 25, 2008 8:12 PM Subject: [Repeater-Builder] Re: How to figure cable length for duplexer? Thanks for the info. I will call call Telewave for an education. The TPRD1454 shows 77db of isolation and a minimum of a 1 meg split. I am running .600 split here. 73's Gary K2ACY --- In [email protected], "Bob M." <[EMAIL PROTECTED]> wrote: > > Telewave is VERY responsive to e-mails and even phone calls. I've had technical questions about their duplexers on several occasions and have sent e-mail to their only public e-mail address. Usually I get a reply later the same day or first thing in the morning from a man named Ray Collins. Turns out he's the president of Telewave and very nice to converse with. Highly recommended. > > I will offer this, however. Celwave (and possibly other manufacturers) seem to have "cut lists" which specify the lengths of coax you need between cavities and from the last cavity to the TEE connector. Telewave doesn't seem to have them; I've asked in the past and I'm always told they make each cable set on the shop floor when the unit is attached to expensive analysis equipment, starting with some known (but un-publicized) length, just to get it close, then they "trim to fit" until the unit performs as they want it to. In actuality, they may have a bunch of cables all made in various lengths by 1/4 inch increments, then select the right ones to get the desired performance. > > You probably wanted a TPRD1454 unit, if they make one, as that would have the right cable lengths and configuration for the 2 meter band. > > Bob M. > ====== > --- On Fri, 7/25/08, garyp609 <[EMAIL PROTECTED]> wrote: > > > From: garyp609 <[EMAIL PROTECTED]> > > Subject: [Repeater-Builder] Re: How to figure cable length for duplexer? > > To: [email protected] > > Date: Friday, July 25, 2008, 7:09 PM > > Jim, > > Thanks for the response. The duplexer is a Telewave > > TPRD1554. They > > are brand new and bought from Tessco tuned. The cable on > > the RX side > > is marked 11" in black marker on the connector and the > > TX side is > > marked 11 1/2 ". Both cables terminate at the T. I > > just want to feel > > assured that they are the right length as I feel my > > performance > > should be much better and want to rule out the duplexer. > > Gary K2ACY > > > > --- In [email protected], Jim Brown > > <w5zit@> wrote: > > > > > > What kind of duplexer is it? I have several older > > Sinclair 2 meter > > duplexers that were up in the 170 mHz range that I moved > > down to the > > ham band, and I had to replace each 10.5 inch cable that > > went from > > the can to the Tee with a cable 12.5 inches long. Turns > > out for > > those older models that piece of cable was part of the > > tuned circuit > > for adjusting the nulls. > > > > > > All duplexers are not made the same, so I think you > > need to be more > > specific. Interesting on the frequency you are using. > > We are just > > putting one on the same frequency here in central New > > Mexico - HI. > > > > > > 73 - Jim W5ZIT > > > > > > --- On Fri, 7/25/08, garyp609 <gary.paul@> > > wrote: > > > From: garyp609 <gary.paul@> > > > Subject: [Repeater-Builder] How to figure cable length > > for duplexer? > > > To: [email protected] > > > Date: Friday, July 25, 2008, 5:46 PM > > > > > > Output frequency is 145.450 & input is > > 144.850. How do > > I figure out > > > > > > what length the cables should be between the rx side > > and tx side > > that > > > > > > connect to the T-Connector? Thanks and 73's ! > > > > > > Gary K2ACY > ------------------------------------ Yahoo! Groups Links
