Airlomba.net

CT7AFR CW-Keyer        

About to finally learn some CW (this time, seriously), I decided to build a small keyer with a small speaker to practice my keying. It all started with a simple 555, but then I became greedy and wanted my keyer to do it all, at least something more than just beeping a speaker. The result, so far, is the kit that I explain in this webpage. If you get one of these kits, I hope you enjoy building it, and even more using it!

For information on how you can order one of these kits, send me a message to the e-mail address provided on the right of this page -->

What you can do with this keyer:
- Operate CW in Curtis Modes A or B, Ultimatic or Bug (setup configurable);
- Send Morse code using either a paddle, straight key ou bug key (setup configurable);
- Adjust the Tone frequency, between 400 Hz and 800 Hz (setup configurable);
- Adjust the character transmitting speed (WPM rate), from 5 to 60+ WPM (setup configurable);
- Adjust the audio output volume (via onboard potentiometer);
- Select the Dit/Dah ratio of either 1:3 or 1:4,4 (setup configurable);
- Select the orientation of the paddle or bug key you are using, Normal or Reverse [see Note 1] (setup configurable);
- Send Morse Code using a radio, in A1A mode (ON-OFF keying), using the provided MOSFET output to drive the radio PTT line;

[1] Normal (or Standard) key orientation is producing Dits with the thumb and Dahs with the index finger (right hand).

The kit contents:
PCBPrinted Circuit Board
U1Pre-programmed microcontroller and One DIP8 socket
U278L05 Voltage regulator
Q1BS170 N-channel MOSFET
Q2BC547 NPN transistor
D1, D2LEDs, 3 mm green
JP1...JP82x8 header connector for Jumpers and One shunt
J1, J2Jack 3,5mm stereo female connectors
RV110 kOhm linear potentiometer/trimmer
C1, C2, C4, C5100nF capacitors
C3, C6100uF electrolythic capacitors
R1327 Ohm resistor 1/4W
R12, R15100 Ohm resistors 1/4W
R14220 Ohm resistor 1/4W
R10, R16820 Ohm resistors 1/4W
R2...R92,2 kOhm resistors 1/4W
R1, R1110 kOhm resistors 1/4W
N.B. This kit does not provide the 8 Ohm speaker, headphones, Morse key, connectors for wires, enclosure or switches.

Schematics (click on the images below to download full size schematics in PDF format)



Electrical characteristics
Power supply voltage:7,5 to 16 VDC
Power consumption @ 13,8V (standby):13,4 mA
Power consumption @ 13,8V (continuous tone):41,3 mA


Configuration of the keyer
To be able to fully configure the keyer, a paddle key should be used. If such key is not available, a pair of push-buttons can be used instead.

TRS


JP # Function Heard signal Dit key Dah key Option cycle Notes
1 Tone Continuous tone Decrease tone frequency Increase tone frequency - -
2 WPM Continuous Dits Decrease character speed Increase character speed - -
3 Key type 'K' (Dah-Dit-Dah) Cycle left Cycle right 'S' - 'P' a)
4 Paddle Orientation 'O' (Dah-Dah-Dah) 'N' - Normal 'R' - Reverse - -
5 Keyer Mode 'M' (Dah-Dah) Cycle left Cycle right 'A' - 'B' - 'U' - 'G' b)
6 Dit/Dah ratio 'W' (Dit-Dah-Dah) 1:3 (dit-dit-dit-dah-dah) 1:4,4 (dit-dit-dit-dit-dah) - -
7 Reserved - - - - -
8 Reserved - - - - -
NOTES:
a)'S' (Dit-Dit-Dit) for Straight Key (a.k.a. vertical key)
 'P' (Dit-Dah-Dah-Dit) for Paddle Key
b)'A' (Dit-Dah) for Keyer in Mode A
 'B' (Dah-Dit-Dit-Dit) for Keyer in Mode B
 'U' (Dit-Dit-Dah) for Keyer in Mode Ultimatic
 'G' (Dah-Dah-Dit) for Keyer in Mode Bug

Videos
I uploaded two videos on my Youtube Channel (CT7AFR). The first one is a time-lapse of the building process the second one is a demonstration of the kit working. The later is spoke in Portuguese but English subtitles are available.
If you haven't seen them yet, please click on the screenshots below:

#1: Building process time-lapse [1:33] #2: Working demonstration [13:39]

Any questions or comments about this webpage are welcome via the e-mail address provided on the top right side banner of this website.

Users gallery

Below are the pictures of CT7AFR-CW-Keyers built by people who gently sent me a photo of their final product. If you want a photo of your keyer to be shown in this page, just send it to me along with you callsign. I will be glad to post it here.

Development First prototype Serial Number: 01 (CT7AFR) Rotary switch instead of jumper
       
(CR7AOL) (CT1HIX) (CT2IUV) (CT1DTE)
OFF AIR
1552
HAM QRZ: CT7AFR
CB QRZ1: AIRLOMBA
CB QRZ2: 31CB117

QRA: EMMANUEL

IARU REG: 1
ITU ZONE: 37
CQ ZONE: 14
QTH LOC: IN51oq

QSL DIRECT TO: APARTADO 517
EC ALTO MINHO
4901-908
VIANA DO CASTELO
PORTUGAL


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