145 MHz pagers
Home Page Up DDAMTEK filters 1.09 GHz filters 145 MHz pagers

 

145 MHz interference - the problem

The interference as seen on a nearby antenna - on two frequencies around 138 and 153 MHz, each containing multiple interfering frequencies!

The 138 MHz group:

The 153 MHz group:

 

145 MHz interference - a solution

144-432 duplexer MX-72N eBay duplexer
 

144 MHz

<==> 6-cavity filter
used end-to-end
<==>

144MHz

Antenna <==>

 
Duplexer
e.g. MX-72N
  

    Duplexer <==> Radio

    432 MHz

<=== ================= ===>

432 MHz


Filter response end-to-end - rejection notches


 

Filter response - passband loss

 

At least I learnt a little more about the facilities in the RIGOL DSA815/TG spectrum analyser!

 

 
Copyright © David Taylor, Edinburgh   Last modified: 2017 Aug 30 at 08:12