Exactly Barry, the 1.8 is NOT going to produce
a crystal clear SSB bandpass, however what it
may allow is to copy that S2 or S3 signal
surrounded by other S9 signals and not be as
impacted as if we were to try the same with
only the 3.0 filter as to AGC desense and such.
Perfect clear copy? No. Possibly good enough? Yes.
Especially with some PBT offset or high/low cutting.
The video I agree was very limited as to any value.
73 de Billy, AA4NU
-----Original Message-----
From: Barry N1EU
Sent: Feb 1, 2013 2:51 PM
To: Billy Cox , Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] Yaesu comparison
On Fri, Feb 1, 2013 at 5:12 AM, Billy Cox <aa4nu@ix.netcom.com> wrote:
Sorry, I disagree, as the ability of the Orion
platform to switch in the 1.8 verses ~3.0 of
the FT5K, would ADD value to the overall chain.
The narrower 1.8 would reduce even more of the
other non-desired strong signals off frequency
that the 3.0 of the FT5K could do nothing about.
That is/was Wayne's key question below, and is
not an option offered by the FT5K, agree?
I agree, but only for signals that are s9+. The threshold for adc overload
depends on the circuit but is typically 15 to 35dB above s9. Any signal less
than that is easily handled by dsp alone.
I think there's some confusion in this thread because several of us were
responding directly to that linked video where the roofing filter clearly
doesn't matter.
But to go back to the OP's orignal question, yes a 1.8Khz roofing filter
instead of a 3.0Khz roofing filter can make a difference, but it's a small
difference. You also need to consider that a slightly off-channel STRONG ssb
signal is more than likely to have wide sidebands/splatter and rf actually in
your desired 1.8Khz passband and there's nothing you can do to filter that out
except rotate your antenna. Yes, if the off-channel STRONG signal is clean,
than the narrower ssb roofing filter can help. Narrower roofing filters are
generally more effective in cw.
73,
Barry N1EU
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|