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: <Repeater-Builder@yahoogroups.com>
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: <Repeater-Builder@yahoogroups.com>
> 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
>
>
>
>
>
>
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