70cms filters

There are plenty of designs available for 437 MHz filters:

450MHz Lowpass Filter

Minikits in Australia make a really good low pass filter which is ideal for use with the Portsdown or other 70cms DATV transmitters.

As used by G4KLB, G8VPG and others.

Simple inter-digital filter

Design by F1DJO and F6GQM first published in CQ-TV 245

Tuneable pass band filter

Tuneable passband filter design by Ian, G3KKD, with 2 MHz band pass and 30 dB attenuation 4 MHz away. (the full article is available in CQ-TV 228).

Built units

The following suppliers sell built and tested units:

• Antennair - suppliers of the DTX1

• DG0VE - German supplier of reasonably priced filters for most amateur bands