Hi Doug, Many years ago I had a similar situation. Instead of using the N06B filter I used the built in hi-pass filter in a Comm Spec PL encoder/decoder board. It is very similar to the NO6B filter. What was happening was that the filter was introducing "twist" (subtle distortion) to the DTMF waveform. The solution was to connect the DTMF decoder directly to the discrimnator output bypassing the filter. You could then try put the filter in line the transmit audio from the controller. However this could be opening up another can of worms because I don't know if you are running flat or pre-emphasized audio and what the effect would be.
73 Bernie Parker K5BP --- In [email protected], "Doug Hutchison" <gb...@...> wrote: > > Hi, > > Have built the filter circuit by Bob Dengler NO6B from the site. > > The unit works a treat but for some reason, DTMF detection fails on my 210 > controller with the filter in use. DTMF is present on the output. > > Any suggestions re what might be causing this would be appreciated. > > Thank you, > Doug - GM7SVK >
