500 cycle CW filter for Collins 75A4; Dave Curry Longwave Products, new
A nice touch is that the filter is easy to reach on the panel, so you can tweak it mid-qso without fuss.
Item Tag: 75A4
2.5 KC SSB filter for Collins 75A4; Dave Curry Longwave Products, new
What stands out about this filter is the gentle slope, which keeps edges soft while still cutting the right signals.
9 KC Hi-Fi filter for Collins 75A4; Dave Curry Longwave Products, new
This filter feels like a natural upgrade, because it tames harsh audio and brings out the clarity you want.