DIPLEXER  2m / 70cm
Felix Meyer HB9ABX
 Update May 27th 2003 / Oct 8 2003
/ 9th December 2018


Duplexers and Diplexers are very similar names and are frequently confused.
Duplexers are devices which separate 2 frequencies within the same band
while Diplexers separates 2 different bands.
The Duplexer requires much more selective circuits while the Diplexer normally
requires only low pass and high pass circuits.

This DIPLEXER separates 2m from 70cm on the same coax cable.
It allows to use 2 antennas over the same cable and permits transmission on one band
and simultaneous receiption on the other band, when connected on the side of the antennas.
Or use 2 equipments (one VHF and one UHF) when used on the side of the transceivers.

Technical data:
- insertion loss : 0.2 db
- separation of bands: up to 70 db

A complete technical description with circuit diagram and adjustement procedure
 for proper operation, together with a list of providers for the required components.

         If you are interested in this article read this.

 Here a picture of a nice construction:


    Feedback received in May 2009:

"Peter Clarke" <pjc...@iprimus.com.au>
To:            felix-...@gmx.ch
Subject:    Diplexer design
Date:        Thu, 14. May 2009 20:11:31 +9.500

Hello Felix,
    I am so sorry to learn about your disease. I have known people with it & they are all doing reasonably well
at the present so please do not loose hope.
   The purpose of my email is to thank you for your design of the 2m/70cm diplexer which since I have changed
my Yaesu FT-897D for an FT847 was most welcome. I constructed it from N connectors on blank printed
circuit board soldered together internally. Being an electric motor rewinder means I have easy access to all sizes
of copper wire for coils & the like. 
It took me about 3 hours to construct & adjust & works like a charm.  I also saved nearly $40.00 over
a commercially built unit, which was not in stock anyway !
     Once again thank you for putting it on the 'net & I hope you get better soon.
Kind Regards,
Peter Clarke
Adelaide, South Australia.  

Here is the construction guide (archive.org):
-   duplexer.html

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