bitx40 module

My bitx40 module from finally arrived on Friday after a 23 day wait. USPS left a ‘We missed you’ note even though my wife was home and I had to go pick it up from the post office, but I finally have it.

The package was slightly damaged during its journey from India to the US.


It was a little crushed, but the board survived. The heatsink on the IRF510 was bent, but I will be replacing it with a larger heat sink to accommodate 24 volts for more output.


I hooked up all of the additional components, except the mic/ptt button and checked the receiver. It pulled the correct amount of amps and everything worked great.


I ended up using a different volume pot because I didn’t have a knob that would fit the included pot.

My goal is to box this module up after adding all of the features that I want. The included electret mic isn’t exactly user friendly and I doubt I would find a way to make it look good. Bill from soldersmoke built this mic/ptt using the included parts, but I wanted to use one of the many mics in the junk pile. I found a Sears mic from an old CB radio that I wanted to use, but an additional circuit was needed to use a dynamic mic in place of the electret. The following circuit acts as a preamplifier for the dynamic mic. It boosts the signal to the levels expected from the electret mic and it uses the power provided for the electret.


I used a 2N2222 and two 100nf caps. Here is how it ended up.


It seems to work okay. There was a contest going on this weekend, so I didn’t test it out on the air, but I did connect the bitx to the dummy load and listened from another receiver and it sounds good.

The only other problem that I have found with the bitx is the drifting vfo that others have mentioned. I plan to add a dds vfo using an si5351 or an ad9850 anyway which would solve that problem. Once all of that is done, I will build some sort of enclosure and have my first real ssb rig.