Re: Modify REV 5 Already Built?


scot forshaw
 

Hi Guido,

Thank you for the reply, 

So to clarify....

Q1 Can the Rev 5 be modified without ripping out half the components?   [yes you can do the original SSB mod - thanks for the instructions in your last post]
Q2 If so, does it have the same features (sdr rx etc) as one built from scratch? [you seem to imply "no" only the generation 1 SSB mod with analog RX is possible?]
Q3 Finally, can it still be implemented with the ability to switch it in / out as in the first incarnation of QCX-SSB? [related to Q1 which you answered already ... the generation 1 mod was reversible but the SDR version of course not?)

Which leaves me still a bit in the grey area, of if it is possible to modify the Rev 5 QCX to the full spec of your latest SDR firmware/capability without having to physically remove major numbers of components?...
I understand that is likely not switchable, but is it possible without taking out all the un required parts?

I am perhaps contemplating modifying my very pristine Rev 5 and can live without the reversibility. I just don't fancy desoldering half the board but would like the full complement of your multiband with SDR features. 

Thanks again and yes if this expands much further I will take across your group.

Cheers
Scot



On Tue, Jun 9, 2020 at 7:45 AM Guido PE1NNZ <threeme3@...> wrote:
Hi Scot,

Yes, if you have a QCX already built you can still run the original SSB mod (without removing half of the components). It also works on as Rev 5 board. To do so make the following changes:
  • SSB receiver: Insert a SPDT switch between C21(+ side) and IC9(pin1) for CW and R27(pin2) for SSB (as was done in original QCX-SSB modification). This will implement an analog SSB backed. If you want to experiment with DSP, you can disconnect the SIDETONE pin, and hook up a loudspeaker with 10uF capacitor in series. It is not an SDR hence you still need to do the analog alignment procedure.
  • SSB transmitter: change D4,R56 (10k); R58 (.22uF); C32 (10uF), remove C31; wire IC2(pin21) to pin R57(side DVM-pin3); wire IC2(pin20) to DVM(pin2); wire IC2(pin18) to junction D4-C42-R58; install a microphone to tip (+ of electret) and sleeve GND of paddle-jack; PTT-switch to ring and sleeve (X1M-mic).


On Tuesday, June 9, 2020, scot forshaw <scot.forshaw@...> wrote:
Hi all,

With the demise of the original QCX before getting a chance to get another to modify, I was combing GitHub to work out if a fully built QCX R5 can be modified without butchering it?

By that I mean, the original QCX-SSB mod seemed to imply just 4 component changes and a few wires...
All the instructions there are for Rev4 boards to do the simple changes required, but then 5 comes along and separate instructions that all seem to consider a new unbuilt kit?
Seems also the project moved on and I can fully work out if the newer revisions of Guido's code and all the improvements will work with Rev 5 "unless everything is ripped out" making it no longer possible to switch the mods in/out.

So my questions are:-

Can the Rev 5 be modified without ripping out half the components?
If so, does it have the same features (sdr rx etc) as one built from scratch?
Finally, can it still be implemented with the ability to switch it in / out as in the first incarnation of QCX-SSB?


I am not particularly worried about backward compatibility I guess, but as it is already built it would be nice if possible.

Cheers
Scot



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