1. QRPLabs@groups.io

Re: QCX vs. QCX+ Form Factor Question

Hans Summers
 

Hi Serge

Yes, I see...

The wide thickness of your assembly is due to the circuit board and the battery holders all adding up as thickness. 

Well there are some potential ways you could make it fit. The area is large. But 30.5mm is the limit to the depth - this assumes the components above the QCX+ PCB are allowed a height of 12mm. The only components which need this height are the LPF toroids, the electrolytic capacitors, and the 24-turn trimmer potentiometers. 

So perhaps, with careful orientation, your board could be positioned such that the "high" parts of the QCX+ circuit didn't interfere with the big parts of the battery controller board. Bolt the board to the roof with standoffs and make sure the positioning is such that the stalagmites never meet the stalagmites. 

OR... use the QCX+ Dev kit board, and separate the battery holders of your assembly, from the board. There seems to be plenty of space to have them side by side. 

OR... you could make the LPF toroids in the QCX+, and the capacitors and 24-turn trimmer pots, lie down - where necessary? The QCX+ PCB has lots of spare area so there is room to make things like down like that. 

Several options - but will take some experiment! 

73 Hans G0UPL
http://qrp-labs.com

On Fri, May 29, 2020 at 1:11 PM Serge, ON4AA <serge@...> wrote:

Here is the Wondom BCPB2 3S 18650 MPPT BMS I am talking about. Leaving out the DC connector, it is still 31.5 mm high with the electrolytic capacitors being the next highest components. However, if necessary, 1 mm can still be shaved off by replacing the 18650 cell holders.

It is pretty cheap, to the point that you perhaps could integrate it with your transceiver by default. The MPPT allows it to be used with a 18 to 24 V solar panel.

I got the idea of a video from Gil, F4WBY. He also employs this to supply power to his QCX radios. (Do not follow his suggestion of soldering directly to the cell terminals, though. Just apply once external power to the board to get it running.)

Wondom 3S 18650 BMS

The newer version PCBs have extra headers to drive external power level LEDs, without the need to add any extra series resistors.
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