Here's some easy modifications to improve the rx audio fidelity of
Kenwood TS-440's. All references below are to the IF board
And, of course, I take no responsibilty for anything you do to
your radio. Be careful. The IF board on the 440' is about the easiest
one to get at.
Increase C60 to a .47uf or 1 uf. This will increase low frequency
response on all modes.
Decrease C51 to .01 uf. This will increase high frequency response
Try removing R263 (tacked on the bottom of the board on my early
production unit). This will lower in amplitude the audio coming
out of the detectors and improved the smoothness (a real technical
term) of the audio, especially on AM signals.