Project ZB-4  
4 Band CW QRP Transceiver by DL6ZB

QRP CW TRANSCEIVER DL6ZB ABACUS-4
QRP CW TRANSCEIVER DL6ZB
 QRP TRANSCEIVER CW SIMPLE EASY
QRP CW TRANSCEIVER 80M 60M 40M 30M
 QRP CW TRANSCEIVER HOMEBREW


Here's a weekend project for the homemaker.

An Analog Devices AD9850 DDS module from the Internet is the heart of this tiny multibander. These DDS modules are usually available for less than 15 US$ / € at Ali, Amazon or ebay.

The AF of the DC receiver is basically a pair of NPN BJTs, a JFET and a single TL084 quad op-amp. I would say that this is the minimum of semiconductor components to make a well working shortwave amateur radio receiver.

The front-end mixer is a 74HC4066 CMOS switch. This mixer is so good that almost no additional filters are needed before the mixer. I added a 3 MHz high pass filter as a precaution to keep strong noise below the filter's cutoff frequency away from the receiver input. In addition, I used a widely available microprocessor and a widely available 0.96" OLED display of type SSD1306 with a size of 128x64 px.

So no components that are difficult to get. Most of it might be found in the junk box of a ham homemaker.
QRP TRANSCEIVER AD9850 DDS ABACUS-4
DDS AD9850 MODULE
 OLED SSD1306 ABACUS-4
DISPLAY 0,96" SSD1306 I²C
 ATMEGA-328P QRP TRANSCEIVER
ATMEGA328P MICRO


Features:

+ AD9850 DDS generator module
+ Microchip ATMEGA328P-PU, 16/20 MHz
+ Rotary encoder for frequency and menu
+ 9k6 RS232 Remote Control, Kenwood system
+ QSK with frequency shift and RX mute
+ Microcontroller sidetone generator
+ Automatic CQ call, also with CQ loop
+ Setup of your individual callsign
+ CW Filter fix for 700 Hz center frequency
+ Contest mode
+ Receiver RIT for split mode operation
+ Relative signal strengh display
+ Battery voltage display
+ I2C OLED display 128x64
+ smooth working IAMBIC keyer WpM 5 to 50
+ Single lever, straight key option
+ Bug key simulation option
+ Output power 5 Watts, MOSFET
+ Elliptic LPF, 80&60 plus 40&30 mtr band

ZB-4 CW QRP TRANSCEIVER WEEKEND PROJECT
 CW QRP TRANSCEIVER 4-BAND
QRP TRANSCEIVER LOW PASS FILTER
 QRP TRANSCEIVER ZB-4 CW OPEN

The receiver is housed in the tinplate enclosure, which is concealed beneath the transmitter and low-pass filters. The transmitter with the output stage transistor is mounted on top of the tinplate case. Behind it are the two low pass filters for 80/60 and 40/30 meters. On the right side are the DDS and the microprocessor.

RF LOWPASS FILTERS:
These filters have an input and output impedance of 50 ohms. I recommend Cauer elliptic filters for sufficient harmonic suppression.
On the photos you can see that I do not use cores with the identification color red (T-50-2). Of course you can do it that way. T37 cores should just work without heating up too much. However, there is still some room for experimentation here. Please email me if you have any suggestions for improvement. The table shown here is just an example.

AF BANDPASS FILTER:
I like it when the CW signal I'm interested in is boosted, but the environment around the frequency still remains audible. Not everyone likes that. Some like a sharp filter that filters out only the signal of interest. This example of a DC receiver offers a lot of room for your own solutions. On the Internet there are a lot of suggestions for narrowband AF filters that are suitable for use in this receiver. I took a picture of the actual frequency response from the band noise from the antenna using SDR software. Note: You can neglect the dB scaling of the ordinate, because it is only relative.

QRP TRANSCEIVER CW FILTER

Push Buttons:
The transceiver has 2 push buttons: <ENC> and <WpM>.
<ENC>  is the rotary encoder's push button.
<WpM> is the multi-function WpM button


 Short Press
 Long Press
<ENC>
 TX ZERO BEAT MENU
<WpM>
 CW SPEED / WORDS PER MINUTE
 AUTO CQ
<ENC> + <WpM>
 QSO MODE:
Auto CQ Loop, 10 times CQ, spacing 10 seconds

CONTEST MODE:
Auto CQ loop, 10 x,  spacing 2 seconds

Table of functions for both push buttons on the front panel.
AUTO CQ may be interrupted by pressing either push button <WpM> or <ENC>.
Without valid callsign AUTO CQ is disabled.

PC REMOTE CONTROL:
The transceiver partially emulates the Kenwood TS-480 PC remote control. The RS232 speed is 9600 baud, 8N1. I have tested the remote control with several PC ham radio software like CQRLOG, DXLab and others. However, I haven't implemented every KENWOOD command, so I can't guarantee that it works with every available PC software.


Click here for download: FIRMWARE ZIP FILE
Clock speed is set to 20 MHz.
Latest: MARCH 31, 2023 V 1.0.12

Please send me an e-mail if you have any questions about the project. dl6zb@dl6zb.de

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The software for DL6ZB's ZB-4 CW QRP Transceiver is freeware in the best sense of "Ham Spirit" with the following restrictions. You may download and use the software for your projects and copy and distribute the download link as you want. You may redistribute the software, but you may not modify the software without my permission. You may not modify the copyright notice. Commercial use in any form is prohibited.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
COPYRIGHT, © ROLF HEINE, EINMUSSER STR. 22, 93345 HAUSEN, GERMANY.