BITX40

I purchased and built a BitX40 receiver back in 2018. My next step of the build is to get the transmit working and address a few issues. I will document my adventures here.

Current issue – Not able to transmit

Currently investigating 7.2000 “birdie” issue.

Link to Youtube video by Juddie(WD8WV) having same issue

Link to solution explained by Allard PE1NWL. 19Mhz VFO and 12 MHz oscillator to be on the low side of the IF using Raduino V2

https://github.com/amunters/bitx40-raduino-v2/blob/master/README.md

https://github.com/amunters/bitx40-raduino-v2/blob/master/operating-instructions.md

Future MOD – 10 Turn 10K Pot – 0.1uF cap on both ends of the tuning pot wire

Link to announcement that production of the BitX40 has ended.

http://bitxhacks.blogspot.com

Modification – inline fuse

http://barrie-wax-group.blogspot.com/2017/04/minimum-bitx40v3-hacks.html

Essential Modes – Limit the reciever from getting RF voltages and suppressing second harmonic to bring transmissions into legal limits.

At pin 12 of K1 relay solder 2 4148 diodes in parallel but in opposite polarity. This will limit the receiver from getting high RF voltage.

Second harmonic suppression at 14mhz MODIFICATION – parallel L7 with a 100 pF C0G (NP0) capacitor

Upated raduini_V1.28.1 https://github.com/amunters/bitx40/blob/master/installation_instructions/0-software-installation.md

I found the circuit diagrams and have them here for reference.

Link to zip file: bitx_with_raduino.zip