Re: QMX Rev 3 Low Power Out Problem
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Ludwig,
Wow! Thank you for that.? I hope to followup with scope today.?? My oscilloscope has 200 MHz bandwidth.? I am a novice user and appreciate your coaching on proper use in this case.
I tried to measure p/s current with DMM and made an error that resulted in destruction of the 12 v leads from p/s to QMX.? I think problem was? DMM mistakenly set to dc voltage not dc current.? QMX booted up ok afterward with a new 12 vdc lead on p/s and direct connection to QMX.
That caused me to stop for the day yesterday.
Plan for today: do the heat checks you described earlier and then check with scope if all is well.
Charles
On Tuesday, June 4, 2024 at 09:12:39 AM CDT, DH8WN@... <dh8wn@...> wrote:
On Tue, Jun 4, 2024 at 05:34 AM, C R Murrell wrote:
- i have an oscilloscope.
Hi Charles, use your oscilloscope, the probe set to 10:1 and good compensated, to check the signal at both connections T501 to BS170 and at one gate of BS170 at each group of BS170. Take care not to connect different solder points with your probe, danger for the QMX. I hope bandwidth of the osci is much higher than the QMX frequency. I checked my HB QMX with 8 V supply at 10 m. Here are the results to compare. If you use 20 m it should be similar. 1) Gate of BS170, same for each group 2) drain of BS170 - T501, same for each group 3) T501 secondary 73, Ludwig
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