I've just installed a YF-122s SSB filter in my FT-818, the audio certainly sounds much fuller but looking at the overall RF to audio spectrum there is considerable ripple and slope - amounting to nearly 4dB over 500Hz to 2.5kHz.? I checked the filter separately, correctly terminated, on a VNA and the response is beautifully flat (<0.7dB peak to peak).
I just wondered if anyone else in the group has seen this effect and dug into possible causes?
Many thanks
Simon
M0AZR
