uBitx V6 GNDREF Connection #ubitx-help #v6 #ubitxv6


Hi all,
GND and GNDREF connections appear on the V6 schema. How are they different from each other? Should GNDREF be connected to the earth, GND battery minus, or can the two be tied together and connected to both ground and battery minus?
TB3EN. 73's

Reed N

It is my understanding that GNDREF is designed to be a floating ground used by most of the transformers in the system. It is not connected to the input GND, or necessarily related to GND in any particular way. I haven't done the analysis to sort out exactly what would happen if it were connected to GND, but I suspect there would be some high voltages passed through that could damage stuff.


Evan Hand

I went back and checked the v3, v4, v5, and v6 schematics.  All are the same with only 2 GNDREF points on T2 and T4.  In the case of T4, it would need to be at the same level as the rest of the board ground in order for the radio to work (Both of the IF amps need it for either input or output).  For T2, the antenna connection is drawn connected to the common ground, not GRNREF.  Based on this, I do not see any distinction between them.  It may have been a holdover from a pre-v3 design, or a simple typo with the copy-paste function when Ashhar Farhan created the schematics.  I have not taken my units apart to look, however, I am confident that the shield connection of the antenna goes to the common ground for the board.

May I ask the reason for your question?  It is better to know how the answer would be used to ensure that we can give you the information that you want.


Reed N

I see GNDREF on T1, T2, T3, and T4 in the v6 schematic, but I went ahead and tested continuity on TP1, and sure enough, it conducts to GND at DC. Only paths are through caps (open at DC) and T2 inductor to GNDREF, so I guess I was wrong!



Hi Evan,
Thanks for your answer. I drawing new PCB and GNDREF and GND confused my mind. I thought maybe GNDREF is directly connected to the earth, but it cannot be independent of the others. But all GNDREFs I understand will depend on GND.

TB3EN Türkiye'den. Elektronik Haberleşme Teknisyeni, Üye YM3KM.


Hi Reed,
Thanks for your answer. I will definitely evaluate that. Have a nice day.
TB3EN From Turkey. Electronic Communication Technician, Member YM3KM.