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	A
Soundcard	Is the soundcard itself	Uses PC soundcard
Audio cables	Shorter	Longer
Modulation relay	Solid SPST	Mechanical SPDT
Separated grounds	No	Yes

Photos

Recommended assembly is stencil, paste and reflow oven

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 5.0

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

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
• RES - Recording input to record band traffic (RES is a typo, should be REC)

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