HERE. HERE. Steve. I agree completely. If one is to own and operate a repeater, One should know how to tune it including the duplexer. This is a learning opportunity
--- In [email protected], "Steve Grantham" <[EMAIL PROTECTED]> wrote: > You know??? Maybe the fellow just wants to experiment and learn something? > In the aftermath of any possible widespread disaster or emergency situation, > he may need to know how to fix something without just the limited toolkit of > a credit card and a postage stamp. Don't we have the opportunity to use > this list-server to facilitate user education? On the other hand, he should > be able to locate a vendor by simply searching the Internet if he wishes. > > Steve, AA5SG > > ----- Original Message ----- > From: "Maire Company" <[EMAIL PROTECTED]> > To: <[email protected]> > Sent: Sunday, March 14, 2004 6:39 PM > Subject: Re: [Repeater-Builder] TX-RX Duplexer Tuning > > > > Send it into TX RX they will tune it at a very reasonable cost and get it > > back to you in a week or so. > > > > > > ----- Original Message ----- > > From: "Eric Lemmon" <[EMAIL PROTECTED]> > > To: <[email protected]> > > Sent: Sunday, March 14, 2004 3:40 PM > > Subject: Re: [Repeater-Builder] TX-RX Duplexer Tuning > > > > > > > Tim, > > > > > > Yes, you can rent a spectrum analyzer- preferably with a return-loss > > > bridge, or you can borrow one. > > > > > > Seriously, though, the duplexer is such a critical component in a > > > repeater system that you really should not try to cut corners on its > > > tuning. Once upon a time, I personally used some "creative" means to > > > tune duplexers, before I decided to acquire the proper test equipment, > > > and I always was able to improve on my prior work, using the proper test > > > equipment. > > > > > > A spectrum analyzer with a tracking generator is the minimum essential > > > tool for tuning duplexers. However, not all spectrum analyzers are > > > accurate enough for such work, and fewer still have enough dynamic > > > range. Most low-end spectrum analyzers have an 80 dB dynamic range, > > > which is insufficient for duplexers that might have greater than 100 dB > > > of isolation. That's where a network analyzer really shines. > > > > > > A return-loss bridge is an important accessory for a spectrum analyzer > > > (it's built-in to a network analyzer), since it allows you to tune for > > > an extremely sharp peak (actually, it's a sharp null) when tuning the > > > bandpass element, thus squeezing the nth degree of performance out of a > > > duplexer. A properly tuned duplexer should NEVER need to be tweaked at > > > the transmitter site. If tweaking a duplexer at the site does improve > > > either the reception or the power output, the chances are good that the > > > spectrum analyzer used to tune it is off frequency. It's also possible > > > that there is a significant impedance mismatch, but I don't want to beat > > > that dead horse! > > > > > > I prefer to use a network analyzer to tune duplexers, because I can > > > easily verify that the jumper cables between cavities are the correct > > > length. In the case of your TX-RX duplexer, you probably should give > > > the factory a call to confirm the cable lengths for the model and > > > operating frequency. Depending upon your location, it may be > > > cost-effective to ship the duplexer to TX-RX, or to another vendor such > > > as EMR, for professional conversion and tuning to your repeater pair. > > > If you do this, do not let anyone touch the tuning controls after its > > > return! > > > > > > The Bottom Line: Yes, you can tune a duplexer without any fancy > > > equipment- but why would you want to, if your objective is to have a > > > first-class repeater? > > > > > > 73, Eric Lemmon WB6FLY > > > > > > timtarhanick wrote: > > > > > > > > I have a TXRX duplexer I am going to use on two meters. Everything I > > read, including the manual from TXRX states I need a spectrum analyzer for > > the tuning the duplexer. Is there any other way besides buying a spectrum > > analyzer to do the job? > > > > > > > > > > > > > > > > > > Yahoo! Groups Links > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Yahoo! Groups Links > > > > > > > > > > > > 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/
