"Bob Cook" wrote in message ...
I have just bought a new Icom 706 mk II G. I believe the standard ssb
bandwidth filter is 2.4 khz.

Icom offers two optional ssb filters, (2.8 khz and 1.9 khz).

I'm curious what the consensus is re the advisability of changing to the 1.9
khz filter.

Or perhaps there is a artical or reference discussing the question.

Thanks,

Bob K9KKY

Unless you are a dx'er or contester in crowded band cdx, I would stick
with the stock 2.4 filter. The main effect of changing filters is
usually in the upper end. Most all filters drop to a fairly low value
on the low end. Or as far as speach is concerned anyway. A 2.4 filter
extends to 2400 cycles with a fairly flat shaping. A 1.9 only extends
up to 1900 cycles. Naturally, the wider filter sounds better. "crisper
mainly, due to the extra high end" If all stations stayed 3 kc away
from each other, there would never be a need for a narrower filter.
But the real world can vary from the ideal. Of course, the 2.8 would
give you the best audio, but the highest chance of hearing nearby
stations, if they are within or close to the edge of your passband.
BTW, in the real world, the filters still allow higher frequencies
through, but at a reduced db level. Most 2.4 filters actually hear out
to about 2.7 kc, where you will see a real steep drop off at 2.7 to
2.8 kc. A 2.8 filter could extend your passband farther than 3 kc if
the signals are strong enough. That means even a station 3 kc away
could be heard. So unless you are an audio buff, and can ignore the
extra noise, it's not really worth getting the wider filter either. I
need a CW filter in mine, but have no need for extra SSB filters. The
stock filter is good enough for gov use. MK