146 MHz filters

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170MHz Low pass transmit Filter

Minikits in Australia make a really good low pass filter which is ideal for use with the Portsdown or other 146 Mhz DATV transmitters.


Low pass 7 pole 144 MHz filter

YU7EF2m LPF 7 pole .jpg Response of YU7EF filter built by G7JTT

A simple DIY band pass filter was originally published in the RSGB VHF manual and described in CQ-TV 250

The coils are wound on a 3/8" or 9.5mm drill.

146 filter.JPG

Example of the design built by M0YDH with help from G8GTZ who formed the coupling capacitor between sections from the loop of red wire and the test results from workshop at CAT17

20170914 CQTV250 2m BPF M0YDH.jpg T.jpg

Mini-Circuits RBP-140 Bandpass Filter

Mini-Circuits make an excellent low power Bandpass filter - the RBP-140 which passes 130-150MHz signals and is for mounting on a PCB. Very low insertion loss. About £16 each or try your luck with an application to their EZ Samples programme.

144 MHz band pass filter by YU1LM

This is a nice easy filter to build and can be used on the output of the Portsdown transmitter before any power amplifier stages.


File:2m BP FILTER-YU1LM.pdf

There is also some discussion on the Funcube dongle website of the YU1LM filter http://www.funcubedongle.com/?p=456

Manufacturers of 144 - 148 MHz filters

  • OCI is a Canadian manufacturer [1]
  • QRP-Labs sell a 144MHz low pass filter kit for <10W duty at $4.65 [2]

Low pass filter kits from QRP-Labs built by M0YDH for Portsdown TX use. 4m on left and 2m on right.