I have discovered the manufacturer will tune the duplexer so it
meets the company specifications - but won't necessarily tune for
maximum performance.
As Eric mentions below, he checked the duplexer for expected
performance.
Neil
Eric Lemmon wrote:
>
> Joe,
>
> I recently installed a complete MTR2000 UHF 100 watt repeater for my
> employer. The duplexer that came with the station was a Motorola
> TLE9022, which is a premium version of the RFS/Celwave PD526-4-2. This
> is a six-cavity duplexer that is specified at 120 dB isolation, minimum,
> and 1.3 dB insertion loss, maximum. I confirmed by testing in my shop
> that it met these specs, which are very good.
>
> The MTR2000 UHF 100 watt PA comes with one built-in circulator, but I
> ordered the station with the "triple circulator option" which adds a
> shelf containing a dual isolator and a low-pass filter. The primary
> load on the additional isolator has a thermistor which connects to the
> station backplane, so that the power will be reduced if excessive
> reflected power is detected.
>
> In my opinion, you can't beat this combination. It is not easy to find
> high isolation and low insertion loss in the same duplexer. Moreover,
> some manufacturers claim higher performance than they deliver.
>
> 73, Eric Lemmon WB6FLY
>
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