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I know Morse code is sometimes used by people with limited use of their hands to interact with their computer. One way is by using a straw connected to a pressure sensor, a so-called sip-n-puff or SNP. I've also read mentions of people with handicaps using it for ham radio purposes. Positive and negative pressure corresponds to dits or dahs, or maybe the other way around. There are several commercial devices, and even headsets that look quite handy, no pun intended.

Reading about this has got me thinking: Is using your hand necessarily superior to using your mouth? Why not hook an SNP up to your keyer instead of a bug? Could you use even use it for QRQ? Are there examples of people doing this successfully on the air?

Our mouths are very agile, and with some practice one can handle very quick and precisely timed breath changes. (In this I speak from my own experience playing fast paced Irish music music on the harmonica.)

One big reason for looking at this in the first place is that I've been troubled by recurring hand pain. Being in possession of a perfectly healthy mouth, I can't help but think "why not use that instead of my hands?" Am I missing some reason not to do it this way? I wouldn't be able to talk while sending, but I would have both hands free.

(If this works well, it might even be an option to practice my QRQ and use this with my computer to replace the keyboard eventually, if my hands keep messing with me.)

EDIT: I got asked how fast I play in the comments. Just walking up and down the scale 500 breath changes per minute is not too hard to sustain. At 600 I keep missing holes and mess up the timing. 400 is easy. It doesn't translate perfectly to Morse characters, but with a keyer 200 cpm = 40 wpm doesn't sound unattainable. 30 wpm even more so. I'm just guessing though! It depends on the hardware and on exactly how reasonable the comparison is.

EDIT2: I've gotten some suggestions for various computer interfaces. Using a computer, and even more units might be possible, but, ideally, I would just have a small two-way switch that I can connect to a keyer or the keyer jack on my portable QRP station.

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  • $\begingroup$ Though the tag [disability] added by @rclocher3 sort of makes sense, I'm not asking about mouth operated cw only as an option if you can't use your hands. I'm interested to know if it could be an alternative even with working hands. Of course the equipment is harder to come by, and it might be more expensive, but from an operating point of view It's not even clear to me that operating by hand is actually superior, though that might well be the case. $\endgroup$
    – EdvinW
    Commented Apr 6, 2021 at 20:37
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    $\begingroup$ I added the disability tag because I thought your question could be relevant to some who do have disabilities. I think you've asked a very interesting question, and I hope that it gets some useful answers. $\endgroup$
    – rclocher3
    Commented Apr 6, 2021 at 22:10
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    $\begingroup$ What’s the fastest you can play an octave scale on a harmonica (16th note run at bpm or mpm)? $\endgroup$
    – hotpaw2
    Commented Apr 7, 2021 at 14:17
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    $\begingroup$ How are your feet? $\endgroup$
    – Brian K1LI
    Commented Apr 7, 2021 at 15:10
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    $\begingroup$ Brian and I must be thinking along similar lines; I was just thinking about a foot-operated iambic keyer, with one foot for dits and the other for dahs. Cobbling one together with foot pedals for the contacts would be relatively easy. Ordinary foot pedals would probably be really slow because they have too much travel, I think. It shouldn't be too hard to design and build a faster foot pedal though... $\endgroup$
    – rclocher3
    Commented Apr 7, 2021 at 15:19

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The SNP specs that I can find online say they can differentiate puffs shorter than 0.25 seconds, which should be good for use as a straight key at at least 5 wpm (maybe 3 to 5X slower than skilled hand keying).

You’ll have to try one out to see if a trained wind instrument musician could operate one faster than these published numbers. Or if a sideswiper, cootie, or bug mode could be used, with both sips and puffs.

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    $\begingroup$ I was thinking of a Sip 'n' Puff keyer: puff for dits, sip for dahs, or something like that. I too wonder if a practiced operator could do better than 0.25 s. Designing an SNP keyer would be an interesting project. $\endgroup$
    – rclocher3
    Commented Apr 7, 2021 at 15:05
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An SNP isn’t very fast at all*. If you’re okay with your mouth being “in use” perhaps a bite-actuated switch in place of (and configured the same as) a straight key would be better. You could “key” much faster that way, I’d bet.

Just make absolutely sure to avoid RF burns in the mouth. :-)

Prototype could be as simple as some contacts and wires on the “open” end of a spring-loaded clothespin with some kind of durable vinyl sleeve over it. Bite the clothespin “open” to close the contacts, release to let the clothespin close (opening the contacts). This way it would behave as a “normally-open” switch.

*See comments. My info about SNP detection speed may be outdated.

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    $\begingroup$ How do you know that an SNP isn't very fast at all? Personal experience? $\endgroup$
    – rclocher3
    Commented Apr 7, 2021 at 1:19
  • $\begingroup$ I've seen some SNP models advertise having a bit of delay, which obviously makes them too slow, but I don't know if this is universal. Is it? Moving your tongue to change sign of the pressure many times per second is not so hard. Just think of all the stuff it's doing while you speak. You suggested method would be a straight key, correct? While it could conceivably be as fast as a hand straight key, I don't think that sounds quicker than changing pressure, unless there is some inherent general problem in SNP hardware. $\endgroup$
    – EdvinW
    Commented Apr 7, 2021 at 7:13
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    $\begingroup$ My claim is purely anecdotal (from reading various sources, an interest in accessibility in computer and software access, etc.) and my information may be 10-20 years behind the current state of the art. $\endgroup$
    – Joshua Nozzi W4JLN
    Commented Apr 7, 2021 at 11:26
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There appear to be MIDI harmonica controller products, as well as keyer software that takes MIDI input. Probably designed from the start to be highly responsive to fast musical rhythms from air pressure change input. And with keyer software support already adapted.

See: https://www.lekholminstruments.com

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  • $\begingroup$ I actually have one of those! I haven't fount any good software to connect it to a keyer. $\endgroup$
    – EdvinW
    Commented Apr 7, 2021 at 20:49
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    $\begingroup$ several GitHub and Arduino projects seem to use MIDI inputs to control Morse Code keying software: github.com/nealey/vail-adapter , maybe vband as well $\endgroup$
    – hotpaw2
    Commented Apr 7, 2021 at 21:01
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SNP keys have been built, and were apparently described in Mars 2004 QST. As I'm not a member of ARRL I can't access it, but the first page of the article can bee seen in the following video:

https://www.youtube.com/watch?v=wsE-S2eXhK0

It says that "experienced users routinely reach 25 wpm or more", which could be interpreted as being comparable with a paddle key. They do continue with saying that "for most of us the puff-and-sip key will never quite match the speed and convenience of paddles", but this could mean various things. If the comparison concerns an operator with long experience with paddles and none with SNP, it doesn't necessarily reflect negatively on the latter.

In the video, the author demonstrates a straight key version, with only one switch. He then notes that he can send faster than with a normal straight key! He only uses blowing to actuate the key, but his contraption seems to use Bernoulli's principle (?) and should work for inhaling as well. If that's correct, and if the switch is fast enough, it should be possible to operate it like a SNP cootie key!

All in all, it seems like SNP systems can be (at least) good enough to make full speed QSO's.

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