Circuit (a) is a blocking oscillator, which runs even with junk-box transistors, powered by a single torch cell. The tone is sharp and horrible, but it's simple. The 220 kohm potentiometer adjusts the frequency.
Start sending practice only after you have the correct sound and rythm of the characters embedded in your mind using Teach. If at all possible, visit the shack of an expert, and closely watch what he or she does with the key.
You'll need an audio oscillator to monitor your keying. There are many types.
Two simple ones I recommend are shown in the figure below.
Circuit (a) is a blocking oscillator, which runs even with junk-box
transistors, powered by a single torch cell. The tone is sharp and horrible,
but it's simple. The 220 kohm potentiometer adjusts the frequency.
Circuit (b) uses 2 gates of a quad 74C00 CMOS NAND chip in a square-wave oscillator, driving a speaker or phones through an npn transistor. The pin connections are correct for this chip, but other CMOS NAND chips are different. Ground pins 1,2,4 and 5 (the other inputs) to reduce current drain. Change the 68 kohm resistor to change the frequency, and adjust the volume with the 1 kohm potentiometer.
Ham radio suppliers still sell morse keys, and so does Dick Smith
Electronics. But the cheap DSE key is too flimsy for serious use.
Ask around at the local NZART Branch, and see if a local will sell or lend
you one. Go for a large, solid, heavy model. Most ZL Hams prefer the
rounded "European" knob - not the flat or slightly dished "American" knob.
Some have replaced a knob not to their taste with a replacement pot-lid
knob from the local hardware store.
Check out the key before using it! Clean the contacts by pulling a
piece of paper through them while pressing firmly - don't
use a points file! Oil the bearings if they look cruddy, and adjust them if
possible to take out any sideways movement. I recommend starting with a gap
of about 1 mm, and spring tension adjusted so the key closes with the weight
of 2 D cells placed on the knob. (You may want to change these settings to
something "more comfortable" after you gain experience). If the start and
finish of
elements sounds "ragged", try connecting
about 0.1 uF across the key contacts to zap keybounce transients.
Secure the key firmly near the table edge . Some operators use
bluetack or plasticine at each edge of the bottom, or even a G cramp or
velcro. It must not walk around! Adjust your chair height such that your
sending arm is parallel to the floor , and not touching
the table . Grasp the key loosely with two fingers atop the knob,
thumb at the side or underneath.
Form dots and dashes by "pumping the wrist", not by pressing with
the fingers! The wrist moves up and down about 1 - 2 cm, with the elbow
stationary. The arm must be relaxed. Tense muscles will tire you,
cause RSI or "glass arm" and lead to later problems. Relax.
To get the relative lengths of dits and dahs correct, start off with this
exercise: Relax: Send the continous element stream
di di di di dah dah di di di di dah dah .....
Tap your foot regularly on the accented (underlined) symbols. The "4 dit"
and "2 dah" segements should take exactly the same time.
(Although the dit:dah ratio is 1:3, when the "dot-space" separator is
included the ratio becomes 1:2.)
Relax! Do not try to send fast! Almost everyone does, and the
tendency is to speed up during practice. Listen periodically to TEACH to
hear again what "5 wpm sounds like". You'll find this speed quite easy.
However, you can send faster for the test if you wish, and many
people actually find this easier, because judging the long spaces implicit in
Farnsworth Morse is difficult. I can't do it accurately either. Try
listening to 12 wpm Morse sent with a Farnsworth speed of 14 wpm, and model
your sending on that. This will also be closer to what you'll end up sending
on the air. But remember, you only have to send at an overall speed
of 5 wpm for the test!
Spaces! Leave plenty of space between letters, and even
more between words! Almost everybody tends to run things together.
This is the most common and horrible fault you'll hear on the air!
Here are several recommendations:
http://www.dxsoft.com/index.html
CWget reads audio morse through the soundcard, and displays the text on the screen. You'll probably need to pass your oscillator waveform through an attenuator (try a 10:1 voltage divider of 1 kohm and 100 ohm) before applying it to the soundcard input. This is the best morse reading program I know.
Remember! Nothing beats an "eyeball" evaluation by an
experienced operator!
If all else fails, send me a cassette tape of your sending for a
diagnostic check. I'll send it back with comments and a recorded
comment.
All keyers vary the sending speed by changing the frequency of a clock, either by front-panel control, or, in microprocessor-controlled units, by commands from the paddle itself.
The best way to check the speed, or to calibrate that of an unknown keyer, is to digitize the audio of a continuous dit-stream with a software package such as GoldWave, and observe the resulting waveform. Find the average time, T, taken to send one dit and the following dit-space. The speed S, in WPM is then
S = 2400/T
Where T is measured in milliseconds. That is, if a dot plus the following dotspace take 100 ms, the character speed is 24 wpm.
A less accurate but more convenient method is to send a stream of dits of known speed, and at the same time send dits from the keyer. Then adjust the keyer's speed control until both sound at exactly the same rate. Some people, especially those with musical training, can do this more easily than others. You will hear "beats" near the correct setting, as the sounds slowly move in and out of synchronism.
To send such a calibrated dit-stream using Teach, click on "Advanced" in the top tool-bar, then "Dits". A text of 10 "@" characters will be loaded into the text box, which can then be sent by clicking the "Send Text" button. "@" is coded as a special character, a stream of 20 dits with no following character-space. Hence this character string sends 200 dits at whatever speed is set. This will take 40 seconds at 12 wpm. This is normally enough to tune the speed, but the operation can be repeated by clicking "Send Text" again.
The default Farnsworth speed is set at 14 wpm. To set keyer speeds below this, shift the Farnsworth speed bar at 12 (lowest setting). However, I recommend that you never use characters speeds less than 14 wpm for reasons covered earlier. If you want to send slower than this, put longer spaces between your characters and words.
If you want to construct an electronic keyer, I strongly recommend the "K9" kitset developed and distributed by Steve, K1EL. I use this keyer whenever I operate portable. Check out his website at
http://members.aol.com/k1el/