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Reviews Categories | Filters, RF: bandpass, duplexer, lowpass, highpass, RFI/EMI | TXRX DUPLEXER 28-70-02A Help

Reviews Summary for TXRX DUPLEXER 28-70-02A
TXRX DUPLEXER 28-70-02A Reviews: 1 Average rating: 4.0/5 MSRP: $$1000.00
Description: TX RX Systems offers a wide variety of Duplexer options to suit your application, including Vari-Notch®, Bandpass, and notch type circuits
Vari-Notch® design provides low loss and high isolation in a compact package
All high RF-current components silver-plated for highest performance
Various models to choose from to match your application.
Product is in production.
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K4III Rating: 4/5 Nov 15, 2016 09:07 Send this review to a friend
4/5! Top notch unless at UHF Congested Site!  Time owned: more than 12 months
It is a great duplexer. I've worked with about a dozen of these and about 15 tprd Telewave/Wacom units. The few peeves I have with this unit is that it uses BNC connectors and RG-142 BNC jumpers. The one other issue is you loose some rejection bringing it down below 444 Mhz as it was made to work between 450-470 Mhz. It has VERY LITTLE LOSS (0.6dB IL) with 100dB rejection, and is easier and quicker to tune than some other duplexers. BUT it only has 45dB "between Channel" isolation. Top duplexers such as TPRD4544 almost double (75dB) "between channel" isolation with little added Inserion Loss! I do not believe these TXRX/Bird duplexers can be adjusted but I could be wrong...

On the flip side, units that have adjustable spinning couplers can increase or decrease "between channel" attenuation and channel rejection. When the TPRD models are tuned to match these, they can also provide 0.6dB IL (Insertion Loss) with 100dB rejection BUT HAVE 60dB "Between Channel" isolation, 15dB better than this model! Plus they use N connectors and RG-214 thick coax cable!

For those who have a lot of UHF channel noise, intermod and interference, tuning the Inserion Loss to 1.5dB will give you over 75dB adjacent channel rejection on TPRD series!

If you are seeking a decent pass/reject duplexer in a country area without much UHF, this is a great find! If you need more rejection such as in a metropolitan city or congested site with UHF pagers and transmitters, you may want to purchase a different duplexer that offers more rejection like Sinclair, Telewave, or Wacom.

Finding out in-band attenuation is very difficult lately, many manufacturers don't publish the info. but something hams should consider if a decent neighbor at congested UHF sites...

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