Range with either type rx exceeded 400 ft tx antenna down, engine running, fm glitching, pcm not.
Are you saying that you were able to get 400' away with the antenna collapsed and a PPM receiver? Any glitching beyond 100' with the antenna collapsed is quite normal for a PPM Rx. A PCM receiver won't allow any glitching. If it encounters interference or lack of signal it just locks out into failsafe until the signal is clear again.