Nuts and Volts - September/October 2018

Introduction

Ashhar Farhan VU2ESE — the polymath from Hyderabad, India — whose Bitx series of transceivers has taken ham radio’s QRP world by storm, is following his recent Bitx40 success by offering the impressive Microbitx transceiver, also known in ham radio circles as the Ubitx (which we’ll refer to it as here).

Having recently introduced the Ubitx to an eager market, Farhan has been struggling to keep up with the high demand for his new radio while receiving reports from many users that Ubitx’s audio chips are failing — some (Figures 1 and 2).

True to form, Farhan has wasted no time in addressing the problem, but as of this writing he’s been unable to nail down the exact cause of the chip’s failure. He’s also not able to say how many of the defective chips have made their way into the user community. Apparently, the defective chips are from a series marked “WX.” Farhan is advising all users who have chips from the WX series to replace them with a chip which is known to work. Several users have replaced the defective chip with the JRC 2073D, and others have used the very reliable LM386. Be advised, however, that the LM386 is not pin-compatible with Ubitx’s chip and will require an interface to be used. Additional fixes for the audio chip problem can be found on Ubitx.net but most of them require somewhat complex modifications to the main board. Unfortunately, Farhan’s decision not to use chip sockets and instead solder the chips directly to the board has unnecessarily complicated the repair.

Farhan stated on his website that the Ubitx boards were thoroughly tested prior to being shipped. Still, the defective chip

Meet the Microbitx:

A Simple to Build, Yet Challenging All-Band Transceiver Kit

Rarely has there been as much interest in a high frequency radio as that shown to the Microbitx.

Low power enthusiasts — better known as QRP operators as well as ham radio hobbyists — have rushed to place their order for this exciting and challenging new transceiver kit.