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Reviews Categories | Speakers for communications use | Skytec CW-1 Speaker Help

Reviews Summary for Skytec CW-1 Speaker
Skytec CW-1 Speaker Reviews: 6 Average rating: 5.0/5 MSRP: $(missing—add MSRP)
Description: Vintage 'Specialty Speaker' from the 1970s. From the one page manual: "Designed expressly for reproducing CW. It has good 'single frequency' selectivity, yet has a most pleasant tone quality, a real boon to lengthy CW operation.

The CW-1 combines an acoustic filter resonant at about 750 Hz with a loudspeaker in a small enclosure. A sleeve in the unit's output opening may be extended to lower the resonant frequency as desired, down to about 600 Hz."
Product is in production.
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W0FEN Rating: 5/5 Jun 21, 2016 08:24 Send this review to a friend
Great for older gear  Time owned: more than 12 months
I had one of these years ago. I used it and it worked. This came out when RXs didn't have the filters that they do now. For a dedicated CW speaker it is great.
WB5AGF Rating: 5/5 Apr 20, 2016 11:57 Send this review to a friend
some additional details  Time owned: more than 12 months
(What follows are some additional comments on the Skytec CW-1 Speaker; read the earlier reviews first.)

If you're reading-up on the Skytec CW-1 Speaker because you're thinking of building one yourself then you need-to-know that the Skytec speaker that you see in the pictures is the outer 'cosmetic' housing. The Skytec speaker consists of a tube-within-a-tube ... the somewhat 'fat' outer PVC pipe housing and a narrower (also PVC) pipe inside.

When you look at the pictures that show the front of the Skytec speaker that smaller 'pipe' sticking out the front (in the middle of the dark plastic 'surround') is the inner portion that provides the acoustic resonance. The inner pipe is built with the same (roughly) 30 degree 'bend' upper section just like the outer pipe; the inner pipe is concentric within the outer pipe but I don't believe that has any effect on performance.

The outer ('fat') PVC pipe has a 3 1/2 inch outer diameter (OD) and the inner (resonant) pipe has a 1 7/8 OD (inside diameter is about 1 3/4 inches). The actual electrical speaker is sitting down at the base of the inner 'pipe' (pointing straight up).

(as has been mentioned by another reviewer) The Skytec speaker is tuned by adjusting the length of the inner pipe - the portion that sticks out the front (in the midst of the dark 'surround') is a sliding piece that fits (fairly tightly) inside the portion that is just protruding out from the dark plastic 'surround'.

In my situation I have been experimenting with different audio frequencies for CW reception, specifically that are slightly lower than the 700-750 Hz that used to be considered the 'standard'. I wanted to see if I liked a 600 Hz note (tone) and to get the Skytec speaker resonant at that lower frequency I made a replacement (longer than the original) slider-piece out of a length of toilet-paper tube (I slit the tube along-its-length, cut out a narrow sliver, and then taped the tube back together so that its OD fits tightly inside the Skytec speaker's inner 'pipe' that is sticking out of the dark 'surround'). With that (slightly) longer 'slider-tube' I can now tune the Skytec speaker to 600 Hz.

Here is some good reading material for acoustically resonant CW speakers :

An Electro-Acoustic CW Filter
QST Apr 1983

A Resonant Speaker For CW
QST (Hints & Kinks) Dec 1987

More On Resonant Speakers
QST (Hints & Kinks) Jan 1989

Additionally, here is a good article that discusses how to build a robust, wooden cased, speaker.

A High Quality Speaker System
for the Ham Shack
QST Oct 2004

It does not have an acoustically resonant speaker but when I read the article I kept thinking that it would make an excellent 'surround' for an acoustically-resonant design.

- Paul, WB5AGF
KE6BB Rating: 5/5 Mar 9, 2014 15:51 Send this review to a friend
This was a nice product producing a sweet CW note!  Time owned: more than 12 months
Found my old CW-1 in a box a couple of years ago, and finally got around to refurbishing it. All that really amounted to was re-gluing the joints together.

I used this speaker with several radios that didn't have good narrow CW filters such a Swan 350, Heath HW101, etc. It really does work. It is adjustable around 700hz (approximately 650hz to 750hz), a common CW note used 35 years ago, but most hams use lower notes today.

The formula for resonance can be found on Wikipedia under Acoustic Resonance of an open cylinder. For those in North America, use care, the dimensions are in meters.

After letting the glue joints set up, I hooked it up to my KX-3. It sounds just as good on that radio as it did on the old radios. I may make a second one to take advantage of the KX-3's stereo audio and its AFX DELAY features. Wish I could just go buy one! Now I have to look for PVC pipe or other tubing.

Stay tuned and we will see how this turns out!
KE6BB Rating: 5/5 May 30, 2011 18:07 Send this review to a friend
This was a nice product producing a sweet CW note!  Time owned: more than 12 months
Found my old CW-1 in a box this week. It needs some work, but it will be worth the effort.

I used this speaker with several radios that didn't have good narrow CW filters such a Swan 350, Heath HW101, etc. It really does work.

The formula for resonance can be found on Steve Weber's website ( as well as a resonant speaker that he came up with, but the CW-1 appears to use the second harmonic making the cavity length half of Steve's calculation.

I can't wait to get this thing cleaned up and glued back together so I can hear the sweet note that it produces.
K4LSX Rating: 5/5 Sep 13, 2008 06:27 Send this review to a friend
a gem!  Time owned: more than 12 months
I am still using one of these - perhaps for 25 or 30 years - amazed that they aren't still available. Absolutely one of the best radio gadgets I ever bought - when used along with the selectivity features in my radio and an Autek QF-1A filter, I can slice anything out of anywhere.
KG6TT Rating: 5/5 Jul 4, 2006 02:56 Send this review to a friend
Novel concept and it works  Time owned: 0 to 3 months
A completely passive CW audio filter/speaker thingie. No power needed. No knobs to tweak! Takes up a minimum of desk space too. Looks just odd enough that you think it might actually work.

I remember seeing these Skytec speakers in the Ham magazines back 25 years or more. They were strange in physical appearance.... a curiosity that I never looked seriously into. Appearance wise (really should have taked a photo) the CW-1 looks sort of like that bent over round air vent on a ship's deck.... or like a slightly 'smushed' oversized beverage can.... what ever paints the picture for you. Less than 8 inches high and about 4 inches in diameter.... white PVC construction with black accents. Not bad looking. I suspect that it was hand made in a small garage shop. Probably no more than a few hundred produced would be my guess.

Anyway a few months back I saw a Skytec CW-1 on an auction site and it got me to remembering. Last week another showed up on that same auction site. This one looked a lot like me... a little worse for the wear. Anyway without much competition it found a new home. After scrubbing away a quarter century of dirt and scuffs a fairly attractive speaker evolved. And it worked.

Basically you connect the Skytec CW-1 to your transceiver and then your normal external speaker to a second connector on the Skytec. A small slide switch at the base of the speaker allows you to change from it to the other speaker.

I am using the Skytec on one of my older but still favorite Ten-Tec transceivers -- a Triton IV from 1976. Now the Triton IV has the optional four stage audio CW filter installed, but I find that using it in the sharpest setting often results in a bit more 'ringing' than my ears like. With the Skytec in place of the normal external speaker (a very full range Realistic Minimus-11)I experience a very noticable audio peaking at around 730 Hz. This speaker's resonant output frequency response resembles a good CW filter and you can hear it! In fact tonight on 40-meters I was listening to a few stations that were very present in the Skytec but nearly lost in the background when I used the station speaker. Amazing. And NO ringing... at least not in the Triton IV's wider CW setting. When I went to its sharpest setting the audio peak from the Skytec was rather astonding. BUT it would ring if the volume was advanced a bit. However that same ringing is present with the Triton IV using the normal expernal speaker and its sharp filter. So ringing in, ringing out I suppose.

Anyway, what a pleasant surprise from the past. Too bad this is a relic that is probably as hard to find as a stable Swan 350! It is a novel idea and a sound design that keeps on working a quarter century later.

You may never ever see one. Then again you might have one gathering dust somewhere. If so why not dust it off and give it a try.... or give it as a curious but welcomed present to a CW buddy. -- KG6TT

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