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Reviews For: W3NQN Passive Audio Filter

Category: Filters, Audio: (DSP and others)

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Review Summary For : W3NQN Passive Audio Filter
Reviews: 37MSRP: 70 USD $75 Cdn $90. overseas
Description:
Passive audio bandpass filter for CW Ed.W3NQN@comcast.net
Product is not in production
More Info: http://W3nqn.com
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
00374.9
W6YE Rating: 2009-04-22
Excellent noise reduction and selectivity. Time Owned: 3 to 6 months.
PRICE: $45.00, postage included to U.S.
CENTER FREQ: 700 Hz

After reading in the 2009 ARRL HANDBOOK (p. 12.41, "An Easy-to-Build, High-Performance Passive CW Filter")
that Ed's kits were still available and reasonably priced, I was very eager to obtain one and try it out. I was
delighted with the results. Ed's address can be obtained from the QRZ.com website by entering his call sign.
QRZ.com members can login to obtain his e-mail address. Ed shipped the kit immediately upon receipt of
my check and it arrived in a few days. Any questions to Ed are answered immediately and in detail.

The kit was easy to build. I would suggest reading all the instructions thoroughly before starting. Follow
the instructions and listen to Ed's hints and you should have no problems assembling the kit. I made
an enlarged copy of the schematic and used it to mark off the connections as they were made.

The filter is a pleasure to use. It has a nice mellow sound with no ringing and broadband noise is reduced
dramatically when the filter is inserted. It's quite an experience to be listening to a weak signal
and see the S-meter being driven to "20 over" by a stronger signal just a few hundred Hz away.
VE7CFG Rating: 2009-03-23
Excellent Audio Filter Time Owned: 0 to 3 months.
This is a great product. I learned very quickly that my IF filters were not needed in most cases. I also find it easier to nail down the zerobeat using Ed's filter. This is on my IC 706. It should be a QSO saver with my cheaper QRP rigs and boat anchors.
K7GLE Rating: 2008-02-12
Very effective Time Owned: 0 to 3 months.
I am very pleased with the performance of this kit. Judging by the spectral displays in DigiPan and TrueTTY, this filter passes about half the bandwidth of the 500Hz IF CW filter in my Kenwood TS-530, with absolutely no ringing. Perfect! Now if I just had another one for SSB…

Price is now closer to $45. Kit arrived in a few days with all parts & instructions. As stated elsewhere this is not a ‘for dummies’ kit, but careful reading of the instructions and examination of the illustrations is all a reasonably-seasoned builder needs. www.WB2ART.com has a good review of the product and its assembly sequence.

Ed supplies a couple of resistors you can use to reduce the volume of the unfiltered signal to match the filtered, attenuated signal. I experimented a bit and ended up using a higher value resistor to achieve a better match. This is a bit subjective, and you need to make your comparison with a signal tuned in the sweet spot.

Also, the enclosure is supplied with the switch and a 1/4-inch audio jack already mounted, and a hole pre-drilled for the input cable. I chose to move the jack and drill a new cable hole to configure the kit for my shack layout.
AA1OF Rating: 2003-07-27
very nice passive filter Time Owned: 3 to 6 months.
The price has gone up a bit, I think its ~$35 now, write him a letter and he will call you. Still a really good deal. Its a passive CW audio filter that is centered on one fixed frequency. Not tiny or light (good for home & probably not for backpacking) but works really well.
You do have to turn the volume up a bit, and you may not think it is doing much at first, there is no ringing, but you will find it very impressive. It's not hard to build. The instructions tell you what to do but you do have to go over them carefully along with the schematic and illustrations. I am quite pleased.
WI0T Rating: 2002-08-17
Good narrow audio filter Time Owned: 0 to 3 months.
Just finished building one of these. Works very good, no ringing or hiss.

One does have to turn the volume up a little more (like the next notch up from normal), but that's expected.

It was pretty easy to put together, but it's not a Heathkit or a Ten-Tec kit. You must read the schematic, his instructions and understand the circuit.

For 20 bucks, it's a tremendous value. The shipping (included in the 20 bucks) was 4.00 by itself. Very nice box, good components. Very good service - he forgot some resistors, he realized it and sent me the resistors w/o me asking. I didn't know they were missing until I got the letter from him. Talk about service!

Good filter, great guy.

W2XS Rating: 2001-08-24
Good Hum/Hiss Reduction Time Owned: more than 12 months.
The W3NQN passive filters are great for eliminating low-frequency hum and high-frequency hiss from the radio's output. If you listen with halfway-decent headphones, these passive filters are mandatory. Older rigs have the hum, but even more modern rigs have some amount of hiss which is present even with the volume control turned all the way down. The passive filters on some Kenwood, ICOM, etc. matching speakers are OK, but the W3NQN filters are designed with more L/C sections for steeper sides and low bandpass ripple which translate into cleaner sound. I built mine from a QEX article and bought the 88 mH coils directly from W3NQN.
AA9NE Rating: 1999-12-04
100 Hz Selectivity - Yet: NO ringing Time Owned: unknown months.
The W3NQN Passive Audio filter gives you real nice sharp skirts
at 50 hz either side of 800 hz center frequency. as an added
plus: Reciever noise pulses did not cause the filter to oscillate;
thus making for uncanny Clarity when copying C-W.

The kit W3NQN, provided to complement the ARRL Handbook
Construction Article, proved easy to build. His well written
instruction made for an error free assembly experience.