[CQ-Contest] YAESU DSP vs. CW Filters
W1HIJCW at aol.com
W1HIJCW at aol.com
Tue Jul 4 12:17:58 EDT 2000
Nice to see your call on the reflector as well as in my log!
I was fortunate enough to have the opportunity to use the MkV for the entire
FD weekend. It was one of two radios in a set up devoted to 40 and 15 CW for
N6ME. The other one was either an FT1000D or an FT1000MP which was filled
(down to the 250 Hz level) with Yaesu filters. We did about 1400 Q's in 22
hours on those two bands, so the exercise was a pretty good one.
First, I agree with Guy (K2AV) that DSP by itself will not in a CW contest
environment replace good discrete component filters. Even with the extreme
flexibility built into the DSP filtering and the extremely fast processor of
the IC756PRO, it just doesn't do as good a job as the discrete/DSP
But probably more important are the impressions I came away with after 24
hours of listening to CW with first one and then the other of the radios
above. My favorite CW contesting radio has for several years been the "D",
primarily because I found its sound less fatiguing over the long haul, but
also because it was brilliant at running with the RF gain down to about 75%
to defeat the AGC, and then using the 250 or 500 Hz filters as needed along
with the Audio Peaking Filter as a tuning device. I tried several times to do
the same thing with MP (used one as a single op in the 97 and 98 ARRL DX
'tests) and found it lacking in responsiveness, mostly because of the lack of
a tunable APF.
This time however, it seems that the MkV has combined the best features of
both the "D" and the "MP". The MkV seems to have the effect of quieting the
edges of the passband. I suspect this is because it steepens the effective
skirts of the passband, but I don't really know. What I do know is that
invoking the narrowest setting of the filters on the MkV and then selecting
from the three APF widths (this is a DSP function) provided truly "single
signal" reception even when the signals were separated by only 100 hertz.
The net result is that as with the "D", I could sit in front of the MkV for 3
or 4 hours at a time and not come away having my ears feel as though I had
been at a Metallica concert. It sounds like my ears are like yours, they do
not respond well to being bombarded. The MkV provided a shield against that
bombardment without ever reducing my ability to hear and copy stations.
On the other side of DSP, the noise reduction capability, the MkV was (or at
least seemed to be) definitely superior to the original MP with no trace of
artifacts that I could hear.
And lastly, of the three radios, the MkV stood up the best to the rigors of
high RF in the environment, variations in quality of power, etc. In fact of
the three, it was the only one which never "hiccupped" during the 'test.
So there's no question about it, if I were going to spend the money it would
definitely be for a MkV along with some optional filters -- whether INRAD or
Yaesu is an open question.
Hope this helps ...
See ya on the low end, 73,
Bill, W1HIJ (/6)
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