Phase 8 ~ Hacking the Bitx40


One of VU2ESE's goals was that the Bitx40 would be an experimenter's platform when the builder would be encouraged to test drive new add on's or other ancillary circuits.

The first hack that I did was the Arduino +AD9850 DDS VFO but the new add on board gives you the digital VFO capability. This now obviates the need to provide detail on that hack. If you have a burning desire to find out how I did it then send me an email to N6QW


There are two worthwhile hacks that I developed aside from the Arduino driving an AD9850 and those encompass reverse voltage protection and controlling an external linear amplifier.

In the case of reverse polarity protection my preference is the second unit where the relay coil must be powered in order to provide voltage to the radio. The wrong polarity will keep the relay open!

Next is the controlling of a linear amplifier so that your 5 watt signal will be heard! This circuit involves just a few simple parts but has been built and tested by me so I know it works. The two 1N4007 diodes isolate the amp control from the rest of the Bitx40 radio.

The blue encased device is the 12 VDC Reed Relay available at your local Radio Shack. Note the two diodes that are installed on the terminal strip. One end of the Reed Relay Contacts is simply soldered to the base copper PC board which is at ground potential. The blue lead goes to the RCA jack mounted on the rear panel. One end of the 12 VDC Reed Relay coil is connected to +12 VDC and the other connects to the anode end of the 1N4007. Not seen is the 1N4148 'snubber" diode which is a 1N4148 connected across the coil with the cathode connected to the +12 VDC side of the coil and is a part of the back emf reduction /prevention.


VU2ESE's web page on has a hacks page and that should be read as well.