[CQ-Contest] YAESU DSP vs. CW Filters

[W1HIJCW at aol.com]

Hi Ed,

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 
combination.

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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