Morse is achieved by turning the carrier on & off.

At the receiver,a Beat Frequency Oscillator is used to create an audible tone when the carrier is present.
The term "CW"as used in Amateur Radio is a historic vestige.

Spark Transmitters produced a "damped wave",so when firstly,high speed alternators,& then tube oscillators were able to produce a "Continuous Wave",although it was keyed on & off to send Morse,it was termed "CW" to distinguish it from Spark.

Hams still use the term for Morse sent in this manner,although it is inconsistent with the Engineering use of the same term.

The original use of RTTY entailed "Frequency Shift Keying",where the carrier frequency was changed in the same manner as audio tones in Long Line Machine Telegraphy.

Nowadays, RTTY in the Amateur Service is achieved by feeding Frequency Shift Keyed audio tones into SSB Transceivers.

A receiver can't tell the difference!

Apart from the original "Baudot" RTTY,we can have "ASCII",& a plethora of more modern systems.

 

one of the neat things about modern electronics is that the digital modes can be decoded with a sound card and a simple free program. the rtty (radio teletype) tones on short wave sound like two carriers about 1khz apart for the commercial and government ones, switched back and forth between at a fairly rythmic rate. FAX( faxcimily) sounds like a rythmic tone with a beat going on every second or so. there is another that sounds like a picolo playing a very bad song, it is called picolo and used multiple tones to represent letters and numbers. search for "soundblaster digital modes" and there are a lot of programs (free and otherwise) to decode these modes.

 

Thank you, that all helps. I still have no definite idea of what those tones are exactly, but all the answers have helped in gaining some knowledge of what is out there.

To use those soundblaster digital modes applications I would no doubt need to make two receivers, spaced at 1 KHz, to feed the channel in. That precision is beyond me at the moment, but it is an interesting thing to aim for, one distant day when I understand a lot more than I do now.

Regarding the frequencies, I believe I found a pair again at 10,919 / 10,918 and 10,949 / 10,948 KHz. I did not have too much time to check for some of the others, and reception was not as good as the other day. I spent what little time I had to listen in on some, apparently Cuban, station on 9,550 KHz.

Regarding my quest to make a regenerative radio, this project in pdf is well within my capabilities, for both available materials and what I can actually do with some confidence. However, it opens a can of worms where understanding it is concerned. I see there are at least three ways to make a regenerative oscillating LC circuit (Armstrong, Colpitts and Hartley). But aside from that, I am not in the faintest bit wise as to how all those capacitor and resistor values are determined.

Plus, I am absolutely petrified of transistors! They are not so easy to find where I am due to some government restrictions on importations (I got lucky and located some remaining low signal NPN, PNP and a JFET, the last which might be useful for an active antenna, soon), and I do not want to blow them "fiddling to find out". The datasheets overwhelm me. Here is an example of one, corresponding to the NPN's I obtained. What bothers me the most is putting too much voltage on the base.

The descriptions I see of transistors define them as a pair of diodes sharing an anode or cathode. This is not the impression I get, and I see them more as a sort of "miniature relay". My own impression is backed up on this page of the AAC manuals. It helps me more to think of them in terms of electron flow, really, as the N-P-N definition is not a very good description of what goes where, polarity-wise.

They are strange, though. Attached is an experimental circuit I put together, which proved to me that they do function as diodes, and are capable of turning themselves on quite effectively. The AC generated in the LC circuit was obviously rectified by the base, turned on the transistor, and allowed the signal to transit the transistor emitter to collector (thinking electron flow). No other power source other than that generated by the LC tank was used. It was as good as the 1N34A, in operation.

In any case, I suppose that is my first AM transistor radio, of sorts. I listened to some World Cup results on it.

PS: So that I don't loose the web location in future, and to give credit where due, I made that diagram on SchemeIt, much quicker than InkScape.

 

Okay.

I would say be very careful and wary of this active antenna circuit, if you are experimenting with "boosting" your antenna for crystal radios.

With my fear of transistors, I assembled it on the bread-board to test it, with all the correct components, and all the connections, especially to the FET, quadruple checked. As the coil for it, I used my reliable iron-dust cored coil, described in a previous post. I hooked it up to my crystal radio of the diagram in the above post. As an antenna, I used an old TV, telescopic antenna. I put the earphone in and hooked up the power. I felt the FET with my fingers immediately, and it was cool. There were some faint signals evident, but nothing spectacular when compared to my outside long antenna.

Then I tried it again, replacing only the 2N2222A "diode" in the crystal radio with a 1N34A. Upon hooking it up, the FET in the antenna circuit became hot. I pulled the power on it immediately, but I believe it is fried. There is continuity on all the legs, at all polarities. I find why this happened incomprehensible, as only one component in a separate, unpowered circuit was changed.

All I can think is that perhaps the better "efficiency" of the 1N34A in the separate crystal radio circuit pulled too much current through the gate to the drain.

I believe my concerns of transistors have been justified. I do not think I will be venturing to use them again for anything, despite the excellent videos and texts addressing them on this site.

That was perhaps the last MPF102 in this country.

 

Well, yes. I have to admit defeat in getting to grips with some issues here. There is way too much on my plate IRL to go "super-hobby" with this. I was enjoying it while it was simple winding coils and making capacitors; as an ex-mechanical engineer, that was right up my street (I had specialized in automobile mechanical engineering at a time when many cars on the road still had points and condensers!). However, certain baits to entice indirectly the notion to try my hand at super-hets led me into a rather unsavoury (for me) world of transistors, which I am in no way prepared to confront.

I have someone bringing out this book for me from abroad, which should be a nice read to go at an easy pace. Some earlier editions were available for download, but in truth I am way too old fashioned and need the physical book in my hand.

Many thanks for all the help that I did get!

All the best.