[TenTec] Re: Roofing filters

[Merle Bone]

Grant/NQ5T said:

That wasn't what I was saying.  Yes, sure the 1.8 KHz roofing filter is
useful in
contests or just 75M at night :-)

.........I work a lot of SSB and normally manually switch in the roofing
filters rather then use the auto mode.
I work a morning net on 20M with another net up 1.5KHz and a second down
1.5KHz. It is
very clear that the 1.8KHz filter makes copying my net possible, many weak
signals, while with the 2.4KHz
filter copy is a real chore due to strong signal interference..


I still sense confusion among some (you not included) about roofing vs. IF
filtering in
the flow of the discussion,  however.   And think we're getting bamfoozled
to some
extent by the option count :-)

.........It is clear from the Sherwood and other independent tests that the
BDR is substantially improved with
the right - usually closest fit - roofing filter installed. It is also
clear, from independent tests, that many of the 7800
weaknesses come from the ineffective roofing filter choices. It seems to me,
from all the independent tests and my own
observations, that Ten-Tec was absolutely correct in their belief that the
roofing filter should be "pretty close
in width" to the IF bandwidth for optimal performance (The 500Hz/250Hz.
amplifier problem aside).

What's unclear to me is "how close" makes a difference.  I recently
installed the new INRAD 4KHz roofing filter for the FT1000MP. It really,
from my perspective, made a huge difference in the ability of the FT1000MP
to copy through close strong signals. It is still not as good as the Orion,
but the FT1000MP is much closer in receiving performance then it was with
the stock roofing filter. I had done many A/B comparisons with the FT1000MP
and the Orion before installing the new FT1000MP roofing filter. I look
forward to seeing the results of  Ten-Tec's continued analysis and learning
about the impact of the roofing filter on the receiver performance.


Merle Bone - W0EWM