[QRO] ssb refresher course needed

[Kenneth D. Grimm, K4XL]

Hi Dave,

I want to concur with what Al said about your posting on splatter and
bandwidth.  I particularly appreciated what you said about ALC lines and
their inability to do what too many think they do!

> But there is a risk in consider that to be the rig's
> bandwidth.  Filters are never "brick wall".  That is,
> outside the designated bandwidth, they are still
> passing energy.  The "banner bandwidth" of a filter in
> ham radio usage is usually the distance between the
> two points where the response is 6dB down from peak.
> And, there is quite a tolerance on that.  In my
> measurement of rigs with stock crystal filters, I have
> seen bandwidths vary from 2.4 to 2.8 kHz when the
> filter is stamped "2.3kHz".

What about DSP filters as found in the recent rigs such as the Icom
IC-756 ProII for example.  Do these DSP transmit filters approach the
"brick wall" as the advertisements would have you believe?  Have you
made any measurements on any of the DSP rigs similar to the ones you
made with the IC-737 and TS-870?

Thanks again for the excellent post.

73 and happy holidays to all,

Ken K4XL
k4xl@arrl.net
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