Hi Hans. Glad your problem is (painfully) solved.? I can;t tell you how many times I've got bitten over the years with:
1. early CMOS chips that had no input protection.? They would get damaged if you looked at them the wrong way.? From where I live, I had ab expression, "CMOS loves the summer, CMOS hates the winter."? In anything I design for my own use, I always make sure devices have built-in ESD protection to the extent available.
2. I learned not to get too clever taking advantage of of a device's unusual internal structure that may not be there from multiple vendors.? I once minimized chip count for a 5 v to 10 v level shifter by taking advantage of a 5V CMOS device that could handle 10 volts on its output via a pullup resistor to 10 volts. This was confirmed by the vendor as acceptible use. I was happy for awhile, then I became unhappy when the vendor stopped making the part.? No problem. I said to myself. There are several other vendors making the part.? But it turned out they were all only 5V compatible on their output. So I had to do a redesign with considerably more parts and was considerably unhappy.
-Steve K1RF
------ Original Message ------
Date 2/23/2024 4:36:53 AM
Subject Re: [QRPLabs] #qmx #shipping update
Hi all
GOOD NEWS... (rare, I know)
I carefully followed the mail tracking number with the domestic courier, for the 350 Nexperia BSS84AK I ordered from Istanbul on Tuesday afternoon that shipped on Wednesday. This morning I saw that it had arrived in the cargo depot in town (12km?up the road). So after I delivered the three kids to their schools and kindergarten respectively, I stopped off at the cargo depot and picked up my small package. A little quicker than waiting for them to put it on their next village van in my direction.?
We tested five QMX Rev 3 boards this morning. I changed the Q202 transistor from the factory BSS84 to the new Nexperia BSS84AK, and asked five different people in my team to assemble the boards, with their miscellaneous ESD fetishes... I'm very happy to report that all five worked perfectly!?
My technician has now started replacing the transistors on 345 QMX Rev 3 boards. I placed an order for 650 more of these transistors so we can complete the replacement on the entire batch of 1,000 Rev 3 boards. We are resuming QMX kit shipments today! Problem solved!
I'm still a bit annoyed that there are multiple kinds of BSS84, some with ESD protection and some without. Even Nexperia have a BSS84 with no ESD protection and the BSS84AK with ESD protection. Other parameters are different between the two variants, and with other manufacturers too. I don't get it, why keep moving the goalposts? Isn't life hard enough already... reminded me somehow of Japan, living in Tokyo 2011 after the great?Tōhoku earthquake in March 2011; standing on solid ground was always something kinda fundamental to my existencialism... but with all the daily aftershocks for a year+, the whole place was all jumping all over the place the whole time. And now I can't even rely on my BSS84's...
On Fri, Feb 23, 2024 at 12:37?AM Dave Schmidt <
dgschmidt@...> wrote:
Wow!? Thanks for the update!? Between new developement, existing support and dealing with supply chain and contract manufacturer's issues, I don't see how you can do it all and still get time to sleep!
Dave
