Davac5

Davac 5 is new design of voice/SSB keyer for Tucnak. Although version 5 may appear to be a successor to version 4, is not true. It brings some advantages but also lacks some features.

To choose the version that best suits your requirements, please look at the table:

Davac versions comparsion

	Davac 5	Davac 4
Size	small	bigger
Drivers required	No	Yes
Isolated	No, use the USB isolator	Yes
Band output	No	Yes
USB	Micro-B or A male	B
Soundcard	Is the soundcard itself	Uses PC soundcard
Audio cables	Shorter	Longer
Modulation relay	Solid SPST	Mechanical SPDT
Separated grounds	No	Yes

Photos

Davac 5 inside box with cables

Recommended assembly is stencil, paste and reflow oven

Version 5.1 with optional USB-A

Features

• Simple assembly
• All parts are SMD
• Designed for SMD reflow
• 3.5 jacks
• 3D printed box
• SMD LEDs + light guides on the top side
• power supply from USB

Circuit diagram

Circuit diagram of Davac 5.1

Notes

• R1, Y1, C2, C4 are not assembled in case of CM108B
• Althrough preferred chip is the CM108B, is possible to assembly older CM108
• The 93C46 is optional but recommended
• The JP1 - Turns ON/OFF the audio mixer - please consult datasheet of the CM108B
• I used LCBB-600 also instead of R9 and R16
• R11 and R17 are for possible coarse attenuation

Connecting to the radio

• MOD - Modulation output to the microphone input of radio
• PTT - Push to talk output to switch Radio to the transmit (active low)
• GND - One ground (ground plane on the bottom layer)

• MIC - Modulation input from headset
• BIAS - Microphone supply (from soundcard, not from radio)

• CW - CW output to key to the radio
• REC - Recording input to record band traffic

=Example for IC7400

LEDs

• PWR lights up - Device is powered from USB
• PWR blinks - Soundcard is playing or recording
• PTT - Push to talk is active (SSB and also CW)
• CW - CW in the rhytm of Morse code
• MIC - The SSR connects MIC to the MOD (off/disconnected if CQ is active)

Trimmers

• CQ - Modulation level to the Transceiver
• REC - Record level attenuator

PCB

Gerber files to order PCB at Elecrow or jlcpcb.com.

Box

STL files for 3D printer.

Recommendations:

• Nozzle 0.4mm
• No support, maybe brim in case of bad adhesion
• Layer height - first 0.3mm, others 0.2mm
• PETG or PLA

Light guides are made from transparent PETG filament.

Parts

Bill of material for tme.eu .

(not including cables)

Set USB string to EEPROM

Only if the 93C46 is installed. From menu Setup, CW keying, Davac5 options.

EEPROM edit in Tucnak