Re: Next PCB rev for QCX-mini #qcxmini #usdx

Hans Summers

Hello Robb

Thanks for the suggestions... some questions inline below

1) Replace the zero ohm resistors with cut trace jumper pads.  i.e. two closely spaced pads with a trace connecting them which you cut with a hobby knife to disconnect the op-amps.  That will eliminate the need to install the zero ohm jumpers (save a few pennies) but will allow one to revert back from the uSDX to the original QCX-mini by bridging the pads with solder.

I understand but is it really easier? Can't the existing 0603 0-ohm resistors pads be bridged with solder to revert back? I've done it, it's easy. 

4) Include some surface mount pads connected to the T1 pads for the installation of the 2x1k resistors and 1nF cap required for the uSDX mod.

It isn't required to leave out T1 for the uSDX mod, if I'm not mistaken. Leaving out T1 reduces performance in both QCX and uSDX. The only reason to leave out T1 is that it makes it easier to go multi-band because the BPF is one less thing to switch. 

Regarding the other points... there aren't exactly acres of PCB area to add through-hole header pads... some might be possible. 

In any event the next batch is already being made now so it is too late to make any changes. I can consider it for the 3rd batch. 

73 Hans G0UPL 

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