Testimonials and Comments
About the W3NQN CW Filter
Steve - K0SR, DXCC Honor Roll
I still use my w3nqn filter almost daily.
Rich - K7SZ
One thing I noticed is the lack of background hiss that is prevalent
in active AF filters. Ed's filter is quiet. Another thing I noticed is the
"mellow" sound of this filter. It is definitely easy on the ears.
Ken - WB2ART
When I hooked it up to my Kenwood TS-570D(g), the background noise almost
disappeared. When you hear a signal of interest,
switch it in. The signal will stand out and all you hear
is that signal. It is remarkable.
Dick - AA6EZ
...DSP drastically alters the audio waveform which I
really don't care for.
That seems to be one of the drawbacks of DSP.
I tend to be somewhat of a
purist when it comes to audio quality.
The W3NQN passive audio cw filter wins my vote, hands down, for good audio quality.
The sharp selectivity does alter
the audio path slightly, wow, no ringing either, however when you give just a
touch more audio gain the sound is great.
If there is insertion loss, and I suspect there is, it isn't a factor.
With careful manipulation of the RF and AF gain controls,
and switching in the filter, I am able
to copy signals that are practically buried in the noise. The analog brain is a
wonderful filter in its own right !!
Theo - PA3GHJ
Because Iím a fan of CW operation and live in a noisy suburban area
in the western part of the Netherlands Iím always looking for ways
to filter out noise and QRM when listening to CW signals.
The kit was received only a couple of days after
ordering and assembling the filter proved very easy since Ed made a very
clear step by step assembly manual and all parts were clearly marked.
The filter was build in a couple of
hours, most time was needed for the glue to dry.
On the first try was the filter successful, I hooked up an old FT 200 rig and
was surprised with the result; clear CW signals without noise or ringing. Then
I tried my FT 2K and there the same effect is present, the filter removes the
annoying audio hiss coming from the sets audio amp that is very present with
high quality headphones and for me it sounds better than the digital audio
filtering in the set itself. I also tried the filter with my 2N 22 XX Norcal
QRP TRX for 40M, there the effect was very good; a pity though that the filter
weighs more than the QRP rig itself!
Marty - W4MBW
I tried several different, both current and vintage, "active" type audio filters
and found them to be uncomfortable to listen to due to ringing and distortion
on strong signals. I have a Ten Tec Jupiter with the 150 Hz DSP filters and
was skeptical if Ed's "passive" 250 Hz filter would even help copy weak CW.
But his very reasonable price was worth trying.
Wow, was I ever surprised! I tried it on a weak 40 CW signal and as soon as
I switched the filter into my headphone circuit the code almost seemed to jump
out of the background and was much clearer to copy...Also absent was a lot of
background atmospheric hiss, even with my DSP filters, and there is absolutely
no ringing. Very pleasant to listen to. With strong signals the CW was clear
with no distortion. Strong nearby signals 200 Hz away were noticeably diminished
and signals 500 Hz away disappeared entirely. The skirts appear to be very steep
but in the bandpass it is easy to tune in signals.
Ed's instructions are also extremely well written and clear. The assembly took me
about 4 hours and Ed's drawings and schematics were very easy to understand. The
filter worked perfectly the first time.
Great job Ed....thank you!
Craig - AC0WQ
Testimonial Sept. 16, 2011
I am so impressed with this filter! I installed it in a Lowe SP-150
Audio Processor that is the companion to the Lowe HF-150 general
coverage receiver (made in the UK). I use these two with my 6 band
homebrew QRP transmitter. The audio quality is outstanding! I pay
a lot of attention to audio quality having spent most of my life in
professional audio applications (AM/FM broadcast engineering and
recording studios). What I hear is the lack of ringing and the
harshness you always hear with narrow bandwidth crystal filters.
The purity of tone cuts through the noise when the signal is fading
down to the noise floor. The leading edge of each dit and dah is
well defined and not smeared like you find with the "expensive"
filters! It is a pleasure to listen to.
In addition to the Lowe/
W3NQN CW Filter combination (the Lowe HF150 also has excellent
audio), I use a companion 3 inch pvc pipe speaker where the speaker
is mounted on the back side and the length of the pvc pipe has been
precisely cut to resonate at the same frequency of the CW filter (600
Hz). The combination of the filter and pipe speaker makes the signals
jump out "in your face" when you hit that sweet spot of 600 Hz. Any
signals above or below 600 Hz just disappear. I might add that the
filter is switched in at the input of the audio power amplifier that
drives the pvc pipe speaker. If you pay attention to good audio,
this is a welcome tool for good sounding CW.
Steve - W7SRM
I could not be more delighted in your filter.
I am running it with my Ten Tec Omni 7. I am
cw only and use headphones about 99% of the time.
The Ten Tec rig has both the 500 and 300 hz Collins
filters installed and a great dsp. Its the best rig
I have owned in 21 years of being a ham. Your filter
makes it better. Even with the 300 hz filter engaged
and the dsp cranked down to 200 hz I see a benefit
with your filter. It takes that band roar background away.
I find I am setting the rig a tad wider at about 400 hz and
then using your filter. That way I keep the audio more
alive and less digital.
The kit was easy to build - just point to point wiring essentially. I followed your
directions and the ones linked to from your site by AK3W. Having just gone through
cataract surgery I used the computer to zoom in on the diagrams to be sure I was
seeing correctly. One other hint is that after cutting off every other wire on the
inductor stack I used a fine tip sharpie pen to draw the connections between terminals.
That really helped to keep it all straight. I may change the input to the back end of
the box from the switch due to my shack set up, but for now I too busy using the filter.
Joe - KB3KJS
I finished building the CW filter late last night. I am absolutely
amazed how well it works. It makes my old boat anchors act like modern
day radios. I can hardly believe what I'm hearing! The kit was very fun
to build and I had no problem putting it together. It worked on the
Thanks for such a great product and kit!
If you have used or built one of W3NQN's CW Audio Filter kits,
we would be happy to hear about your experience.
Please send your comments and feedback here.
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