开云体育

I've removed the DC power socket from my QMX and replaced that with silicon 16 AWG (thick so that the solder joints should be quite resilient) which is terminated with powerpole connectors. In the circle, on the 5V smps board, I've removed the stock Zener with a 5 Watt version for improved power protection (as discussed elsewhere in this forum) in case of unexpected input power fluctuations. The new Zener is too large to fit in place on the board, so I had to solder 2 very short wire stubs to the board and attach the new Zener to them. Then I squeezed some electronic grade silicon under it to keep it from bouncing around. You can see I put dabs of that goo around other components to prevent them from vibrating while traveling with the QMX and potentially breaking away from the board over time.

One other word of caution,?NEVER REMOVE THE 5V SMPS BOARD WITHOUT FIRST REMOVING THE 3.3V BOARD. Otherwise you'll inevitably sheer a diode right off the top of the 3.3v board. Don't ask me how I know this! :-(?

Groups.IO removes photos on a regular basis (for space reclamation). So here's an external link to the photos I've posted. In the red circle is my replacement of the small Zener diode with a more robust 5W version. From what I understand, this mod is not needed in more recent releases of the QMX as the higher wattage Zener is installed by default. This is a 2023 Rev. 1 board. If I recall correctly, starting in 2024 the stock SMPS boards are already upgraded.

Also shown is my QMX with power-pole connectors instead of the stock barrel connector. The wire hanging out of the QMX makes it less pretty, but should significantly reduce the risk of getting the power jostled loose if the QMX is bumped during operation.




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73
de Roy - KI0ER
Littleton, Colorado USA

There are two sizes of 5.5mm power connectors, 5.5/2.1 mm and 5.5/2.5 mm. The 5.5/2.5? plugs will fit in the 2.1 sockets but the result is a poor connection.? Sometimes you order a 5.5/2.1 plug and actually get a 5.5/2.5 one.

The only way is to check, use a 2.5mm drill, if the drill shank will fit in the plug it's the wrong sort.

As for the frequency the usual pattern is that something can't happen, then no one else has this, then very rare, then can only happen under very unusual circumstances, finally happens every time the right conditions are met.

I've seen both on a professionally made ?3000 computer controlled telescope I have.

Chris, G5CTH

I've added the PSU tests I proposed back in June last year to the files area.

/g/QRPLabs/files/QMX%20power%20and%20voltage%20tests.txt

Chris, G5CTH