I do not have the Bitx40, however the current version of the BITX40 uses the same Raduino as on the uBitx v4.
The Raduino 7805 regulator also gets hot because it is dropping the 12v in down to 5 volts.? The 7805 used in the Raduino can do this, however the power dissipation is close to the limit for the device without a heat sink.?
I did two things to solve it for the uBitx that I have:
1 Added a heat sink
2 Added a voltage dropping resistor.?
It is really easy to add the heat sink, and should be done in my opinion.
If you go to step 2, the wattage and resistance depends on what is connected to the 5v source; for the uBitx with Nextion display and other components I added a 4 ohm 5 watt resistor in series with the input to the 7805.? This gives me up to 1 amp of 5v for multiple displays and nanos for increased functionality.? For the standard Raduino with nano, and assuming 12v input to the rig, the value can go from 4 to 47 ohms.? The ubitx draws less than 120 ma on the 5 volt regulator with the standard display.? If you have no plans to add on other 5v devices, I would use a 47 ohm resistor rated at 2 watts.
Again, I do not have a BITX40, so a number of assumptions were made on the above from the information on line. It also means I do not know the calibration process for the BITX40, someone else will need to help you there.
Happy New Year and 73
Evan
AC9TU
