146 MHz filters

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.

Or there are a number of published designs which are easy to build using a minimum of tools:

Low pass 7 pole 144 MHz filter

A simple DIY 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. Example on the right is by M0YDH with help by G8GTZ.

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]