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Reviews Categories | Filters, Audio: (DSP and others) | W3NQN Passive Audio Filter Help

Reviews Summary for W3NQN Passive Audio Filter
Reviews: 25 Average rating: 4.9/5 MSRP: $70 USD $75 Cdn $90. overseas
Description: Passive audio bandpass filter, center frequency 800Hz eMail:
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KI0Z Rating: 5/5 Apr 11, 2012 18:36 Send this review to a friend
AWSOME  Time owned: 0 to 3 months
ANYTHING THAT CAN HELP THE TS-590 & IC-7800 is worth looking at!! this is an amazing design .. I have had a lot of filters but this Active filter Is a big help WOW ........!!!!!!oN THE ts-590 NR-2 WHEN LISTENING TO cw YOU GET THE POT HOLES OF REMOVED BAND NOISE SPACES AND THE cw SIGNAL. turn on the W3NQN filter and it's just CW signals only !!! even on wide filter settings of the xcvr it has a lot of selectivity. just set it up for stereo plug and jack.Don't short out 1/2 of the signal out of the xcvr with a mono plug!!tye both hot of plug to input wire and have full output at filter.same as at xcvr.use the filter on the IC-7800 snd hesr both rcvrs in both ears at once with stereo setup. . GL 73 DX Dave KI0Z..
W8FA Rating: 5/5 Mar 7, 2012 16:21 Send this review to a friend
Save your ears, get this filter.  Time owned: more than 12 months
I can't say enough about this simple PASSIVE audio filter for CW. I use it every day. There is no ringing, echo, hiss or roar. It is so much more pleasant to listen to the band background noise using this filter compared to others I've used, which are either built into the rig (crystal or mechanical), DSP, or, are an outboard accessory, for which I have a box full, with some costing $500. THIS FILTER DOES NOT ADD DISTORTION TO THE RECEIVED AUDIO like typical active filters, DSP, etc. It also makes it easier to dig weak signals out of the noise level. The kit was easy to build. I did add extra output connections and switches on the filter box in order to direct the output audio to other pieces of equipment, speakers, and multiple headphones. The only problem I had was with two inductor wires broken at their solder connection point. I quickly found this problem after checking with an ohmmeter, but could have seen the bad connection if I had opened my eyes. You do not have to be a homebuilder to build this filter. It's simple point-to-point soldering at about two dozen points. There is even step-by-step pictures of construction on the website which you can click-on and enlarge. If you operate CW, save your ears and get this filter. Does it work miracles? No. The band noise is still there, although at a reduced level. But most important, the noise is less tiring. And without distortion. I plan on using this filter for life. This is one of the few accessories I've used in the last 40+ years that really works. Considering what a simple passive filter like this costs, I can't figure out why the big transceiver manufacturers don't build these into their multi-thousand dollar rigs. Oh wait, maybe I can figure that out.
G3LGR Rating: 5/5 Mar 7, 2012 07:51 Send this review to a friend
Excellent non rringing filter  Time owned: 3 to 6 months
Recently purchased a 600Hz version of the filter from Ed to carry out some very low signal to noise tests.
before starting the tests I tried the filter on my IC 706 and FT 897. The filter has been a pleasure to use, no ringing, just an absence of noise and reduction of nearby signals. I've not bothered using my 599ZX on the HF and found that the filter when combined with the BHI DSP unit at a low setting has provided a very nice relaxing way of sorting out weak Cw stations, especially on my favourite band, 40 metres.
Ed produces the kits at various frequencies from 500 Hz upwards
N7AG Rating: 5/5 Apr 5, 2011 00:31 Send this review to a friend
THE CW FILTER  Time owned: more than 12 months
If I could have but one cw filter, this is it. His website is most useful for construction. Filter is not tiring to listen to. Have tried numerous DSP, low-pass filters.
F6DFZ Rating: 5/5 Mar 3, 2011 10:18 Send this review to a friend
Impressive  Time owned: 0 to 3 months
I have just finished my W3NQN CW filter and put it in service with my Collins 51S1 receiver. The improvement is absolutly impressive. This filter increases the selectivity (generaly 51S1 comes with a 800 Hz Bulova crystal filter), improves the sound of CW signals, reducing the distorsion introduced at the attack by the AGC, greatly reduces the back ground noise, and supresses the switching transcient when transmitting with the Collins KWM2A. Of course, the 1750 Hz from the KWM2A side tone is filtered out. I solved this question with the injection of the side tone from my keyer in the RCA ad hoc plug on the back of the 51S1.
A very worthwill addition, even if you own a modern rig.
WB6SSW Rating: 5/5 Nov 29, 2009 16:50 Send this review to a friend
Amazing Performance  Time owned: 0 to 3 months
I've got all homebrew station. The receiver is an HBR-16, a design from the late 50's with no selectivity other than what it can muster from dual conversion and two stages of IF. No crystal or mechanical filters and, of course, no DSP. Ed's (W3NQN) filter turned a nice project radio into a great CW receiver.

The filter comes in a kit of parts, a surplus telco five inductor toroid stack, two additional 88 mH inductors, two small audio output transformers, a bag of capacitors and a bunch of hardware (box, switches, etc.) Ed takes the time to mark the capacitors with their appropriate schematic designation, C1, C2, etc.

Assembly is fairly straightforward. Ed suggests using silicon sealant to mount the capacitors and toroids to the telephone inductor stack. I used a hot melt glue gun which worked just fine and I didn't have to wait to the glue to dry.

I am sure that most buyers will take the outboard approach and use the box, plug and jack to house the filter. However, in my case this was going to be a integral part of my homebrew receiver. So the hardest part of the project was finding room for the filter and the two audio transformers, because this filter is BIG. The assembled filter without the audio transformers is about 5" long 2" wide and 2.5" tall, and weighs just about one pound.

After making room in the receiver, mounting the components and wiring up a front panel "wide/narrow" switch, it was time to test it out. Wow. What a difference. About a 300 Hz passband at the -6 dB point at 450 Hz at-20 dB (Ed reports 325 Hz and 460 Hz and my measurements were a bit better than that).

Best of all, as has been reported in other reviews of this filter, no ringing. A real pleasure to listen to. And, it's kind of spooky seeing the S Meter jump around from signals outside of the filter passband, and not hearing a thing from the speaker!

If you've got a "wide" receiver and want to use it on CW, this may be just the ticket.
K3ANG Rating: 5/5 Apr 24, 2009 21:35 Send this review to a friend
Worked well when I had it  Time owned: more than 12 months
I got one of these kits from W3NQN back in the 1980's. A fellow ham had one, let me try it out, and I just had to get one. Worked very well. I lost it back in 1995 during a move to my current qth.

To KB9WIS: Go to QRZ.COM to get W3NQN's snail mail address. That's the best way to get HIS KIT. No one sells them already made. You have to build it.

de K3ANG
KB9WIS Rating: 5/5 Apr 23, 2009 14:57 Send this review to a friend
Where to Buy  Time owned: 0 to 3 months
I know this is for reviews only, but can anyone tell me where to buy or order one of these filters for SSB use? I can't find a website or phone number anywhere, so don't know how to order them..

If anyone knows, my e-mail is:

Thank you,

W6YE Rating: 5/5 Apr 22, 2009 22:44 Send this review to a friend
Excellent noise reduction and selectivity.  Time owned: 3 to 6 months
PRICE: $45.00, postage included to U.S.

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 website by entering his call sign. 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: 5/5 Mar 23, 2009 15:57 Send this review to a friend
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.
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