Randy, I don't know if it would be significant, but did you consider magnetic shielding? A steel jar lid might work.?
--
73, Dan? NM3A

TI actually has a white paper on failure rates on the documentation page for the chip, for those who would like to do a little casual reading. It's more generic for their manufacturing process and quality control, but it's an interesting read anyway.
--
73, Dan - W2DLC

Add me to the list that had to replace the 1804 .

I had never thought about counterfeit.? At least one aliexpress seller seems to think calling their's?
non-counterfeit is a selling point.



I guess there are a lot of counterfeit 1804's out there.

Don statement is not? generally true for batteries.?

Between 35 C and 40 C there is a temperature that will trigger a massive slump in? Pb battery output (the? exact triggers for the voltage slump were not? know when I was doing O and G work) .? The big operators like Exxon Mobil and? Texaco will not allow? any sort of Pb battery to be used for critical? unctions on offshore platforms for this reason.? Consequently the poison of choice was? NiCad or? late NiMH battery packs.?
T

I'm waiting for my replacement PCM1804, too.
Hoping that it will solve the issue with my QMX.

I would agree to Andy. There seems to be an issue with this chip, but if you just take a look at the order backlog for the assembled devices and Hans comments about packing 1000+ kits, the defects are still in the permille range.

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On Thursday, 11 July 2024 05:18:32 -04 John Rabson via groups.io wrote:

> Is the 1804 a successor to the COSMAC 1802 which we flew in Oscar

> seven and Oscar nine? It was the only space qualified processor which

> we were allowed access to.

Greetings John,

it is an A/D converter. Please see attached datasheet.
>

> John G3PAI F5VLF

>

> > On 11 Jul 2024, at 10:56, Philip Thompson via groups.io

> > <pcteee@...> wrote:

> >

> > Hmmmmmm!? this PCM1804 issue is giving me the jitters!

> > Ordered a QMX+ a few days ago and if this is a problem. I don't have

> > the tools or skills to replace the chip. If I do get a faulty one,

> > is there a returns procedure or is the board scrap? Being

> > pessimistic I know but there seems a fair amount of chat on this

> > issue... Fingers crossed

> > Phil? G4JVF

Hi Phil,

it happens very rarely.
If you sift through the archives you will find several knowlegable OMs who have the skills and the equipment to help in such rare cases.
Wether you ordered a kit or an assembled unit? make yourself thoroughly familiar with the assembly and operating manual before you start building/using the QMX(+).
Also have a closer look at this video:

?

73 de Eike

--

Eike Lantzsch KY4PZ / ZP5CGE

On 11/07/2024 09:56, Philip Thompson via groups.io wrote:

I don't have the tools or skills to replace the chip.

But you have ham friends who probably have?

Or there will be someone on here local-ish to your QTH who can help.

And remember, you only hear about the problems not the many hundreds of boards that work fine first time.

On 11/07/2024 10:18, John Rabson via groups.io wrote:

Is the 1804 a successor to the COSMAC 1802 which we flew in Oscar seven and Oscar nine? It was the only space qualified processor which we were allowed access to.
John G3PAI F5VLF

No.

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Is the 1804 a successor to the COSMAC 1802 which we flew in Oscar seven and Oscar nine? It was the only space qualified processor which we were allowed access to.

Hmmmmmm!? this PCM1804 issue is giving me the jitters!
Ordered a QMX+ a few days ago and if this is a problem. I don't have the tools or skills to replace the chip.
If I do get a faulty one, is there a returns procedure or is the board scrap?
Being pessimistic I know but there seems a fair amount of chat on this issue...
Fingers crossed
Phil? G4JVF

The devil is in figuring out in which step of the procurement to testing process most A/D failures happen. Hans likely has some failure data from the kits they've assembled. I wonder how those compare to field failures (admittedly a harder number to compile)?

Thanks Hans :-)

Listening to it again, I think what you were talking about was that the QMX has built-in test and alignment tools, similar to QCX.

Very interesting presentation b.t.w. really enjoy getting more of an insight into the clever design behind these kits.

In the recent QMX+ talk Hans gave to the RSGB



At around 47:00 he mentions terminal emulation via putty for the QCX...

Did he maybe mean the QDX ?

I've had a look at the operations manuals for QCX, QCX+ and QCX-mini, and find no references to terminal emulation ...

Steve, I’m working on the speaker idea also.
Have you found any issue with the speaker’s magnetic fields interfering with the toroids directly below?
I’m doing a half height implementation so if you have issues mine would be worse with the speakers sitting directly on the dev board just 5mm above the toroids.
I’ll probably run through all the tests for each band with and without the speakers just to see what it looks like.
--
Randy, N4OPI

The QMX has been sold.

--
Jim / K7TXA
Eagle, ID

SKCC 10447T
BUG 301

Is there a chart of pre-power up resistance measurements?
Power socket is 15 Mohm
Antenna socket is 0.7 ohm
--
Dan Reynolds -- KB9JLO
<><