In article ,
"Bob D." wrote:

Is the optional YK-88SN-1 SSB filter worth buying?

What do the add-on filters do anyway? Are they an improvement over the
original filter, or do they just give you an optional bandwidth?

Bob-

I have that filter in my TS-690S (A TS-440 with 6 Meters). I can't say
it is an "improvement" over the original filter other than as an
optional bandwidth. To me, it is worth having the narrower filter when
the band gets crowded, and it helps a little with noise as well.

I understand the TS-570 has Audio DSP filtering. You may not need the
noise reduction of a narrower filter, but Audio DSP won't remove
interference from stations on an adjacent channel.

Fred
K4DII