Re: QMX ---PCB Rev 2 -- #qmx
开云体育
Hans,
Just a quick note, I am not a William. Billy Wayne Moore is my real name. I was raised as a real Texas cowboy on a ranch in the Texas Hill Country. Yep, riding a horse, chasing cows, roping and the whole nine yards. Laid on the floor behind my father's rocking
chair and read by kerosene lamp (we only had two). From 8 years old on, I dreamed of being a physicist; and I made it. Just thought you might get a kick out of this. Look at my website
for the rest of the story.
Billy
From: [email protected] <[email protected]> on behalf of Hans Summers via groups.io <hans.summers@...>
Sent: Monday, August 28, 2023 09:41 To: [email protected] <[email protected]> Subject: Re: [QRPLabs] QMX ---PCB Rev 2 -- #qmx ?
Hello Willie
> I am a retired physicist on the north side of my eightyth decade.
I am also a physicist (graduated 1993, Imperial College Physics BSc, London university); but have never officially been a practicing physicist (debatable)! Please do also refer to my 52-tips video?
which gives construction advice.?
> In doing due diligence, one has to ask the tough questions.?
> Does management see a Revision 2 PCB board on the?
> way with all the known fixes on it??
I always do new PCB revisions, particularly in the early days of a product (say, the first year). There will always be a little tweak that I can make that will make construction marginally easier. Such as a slightly moved pad, or a slightly larger hole
someplace.?
There are very very few issues with QMX (surprisingly few).?
1) A manufacturing defect: the SMPS has a potential short between Q103 and Q104 drains which appears to affect around 10-30% of boards. However we are now testing all SMPS boards before shipment and fixing any that have the short. Therefore this problem
is ALREADY solved... nobody ordering now needs to worry about it. For the next batch I'll move Q104 a little further away just to remove the need for any corrective work pre-shipment.?
2) Missing 5.1K pulldown resistors on the USB CC pins, which are needed if you are using a device with a real USB-C port, and a direct USB-C-to-USB-C cable (not an adapter).?
3) 20m Low power was an assembly instruction error; 20m low receive sensitivity was also resolved and is just an amendment to the manual.?
So really, yes there will be a Rev 2 PCB, but it is minor stuff, and there will nothing wrong with having a Rev 1 PCB.?
> Would new firmware depend on having the new Revision?
> 2 PCB board leaving the Revision 1 QMX units behind??
NO! Like all the QRP Labs kits, all firmware revisions in general work with all PCB?revisions. Even the latest QCX firmware can run on the oldest Rev 1 QCX-classic PCB from 2017. If there is some new hardware feature such as the on/off controllable backlight
on QCX-mini, or the CAT control port in QCX, then yes that requires some specific hardware modification etc. or PCB revision.?
Hi Chris
> Also, I am looking forward to building a second unit for?
> high bands but I expect this will be delayed until the?
> problem with some QDX having low power on 10M?
> (Possibly QDX T1 identical to QMX T501) is resolved.??
> Hans does the QDX low power also happen with the?
> 9V T1 winding.
That was already resolved, Chris. The 12V QDX is less likely to suffer low power output, the 9V QDX is more likely to suffer low power output. The solution in both cases is a new output transformer design by Ross EX0AA. If you search this forum for "WTST"
(Weird Twisted Sisters Transformer) then this is the solution for a high-band 12V QDX. If you search the forum for "RWTST" (Really Weird Twisted Sisters Transformer) then this is the solution for the high-band 9V QDX. The twisted output transformers completely
solve the problem of sometimes getting low power output on 10m.?
FYI we are also using the same twisted transformers on all QMX we assemble here in QRP Labs HQ for people (12V WTST and 9V RWTST).?
I do need to urgently update the QDX documentation, and the QMX documentation (ahead of the high-band QMX where the twisted transformers shine).?
73 Hans G0UPL
On Mon, Aug 28, 2023 at 4:35?PM Chris KB1NLW via
<chrisrey1=[email protected]> wrote:
Hans incorporated two major hardware features that require future firmware.? These are SWR measurement and the ability to modulate RF amplitude.? I believe that the first firmware that combines the features of QCX and QDX has required more debugging than expected.? There have also been a couple of significant hardware issues that were resolved.? -- N5SE Billy Wayne Moore 7066 Shady Knoll Ln Willis, TX 77318-6324 Phone: 936-537-2975??? |
N5SE