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Low Voltage in QCX
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Kevin Keppler
All,
Unable to get peak or null in RCV alignment steps. Voltage between R1 and R2 reads 1.8V. With T1 and IC4 disconnected, voltage between R1 and R2 reads 2.46V.
Before I disconnected some leads on T1, it showed continuity across each winding. Does this mean IC4 has a problem? IC5 and associated?
Kevin AE1EI
Sent from Mail for Windows 10
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Jelle
Good morning Kevin, I have the same issue. T1 windings 6,7 at 1.77V. This is the same as pull-up point between R2 and R1. I find an in-circuit resistance of 5k over R2. But I don't see where that would come from. And under these circumstances I get a BPF Peak of only scale x4 with 7+2 bars. Keeping a close eye on this message. Many thanks, Jelle |
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Kevin Keppler
Jelle,
Nothing heard for a week. I posted here after posting on FB and then writing to Hans. Hans suggested I post here and see what I get. I will write to Hans again and let you know. AE1EI Kevin |
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George Korper
It would be most helpful if you provide more details Which QSX, what band? What revision? What power source? Since 90% of problems are associated with T1, you may have continuity but how many turns are on T1 and how did you remove the enamel. Sorry you were missed, help is on the way! On Fri, May 22, 2020 at 8:10 AM Kevin Keppler <kkeppler9@...> wrote: Jelle, |
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If you look at the schematic, you will see that some of the T1 terminations are connected to Gnd. Hence you can not check for shorts between winding sin circuit. Check the extensive troubleshooting guide for help. https://qrp-labs.com/qcx/qcxtrouble
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Kevin Keppler
George,
Thank you for your attention to this. It is QCX40, rev 4 2017. For 40m, # of turns is 5/5/5/38. Continuity was tested from various points on the PCB without touching the wires. Wire was scraped with a cutter blade. Power was 8 X AA, then a switching supply set to 12.6. Thanks again, Kevin AE1EI |
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ajparent1/kb1gmx
MAkes no differece what QCX or what band they are all the came circuit.
Of that point is not 2.5V you have a error or s short maybe just a misplaced part. Make sure R1 and R2 are really 10K. also a short at the output side of IC4 namely possible at C43,44, 45, 46 could cause that. Allison ------------------------------- Please reply on list so we can share. No private email, it goes to a bit bucket due address harvesting |
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Kevin Keppler
Allison,
R1 and R2 are each 9.97K. In circuit, C43, c44, c45, c46, and C6 show no continuity. I will reconnect everything and test the voltage one connection at a time. Thank you, Kevin AE1EI |
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