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Re: Problems with QCX build, guidance needed please

 

Mark. On 8.7 there should also be a number associated with the displayed deflection level. The reading increases on the scale until the scan number goes up to its highest value. This is typically 7 or 8 on the 8.7 adjustment. If that is the case then audio is good all the way to the IQ balance pot. If not, the problem can be anywhere including the lowpass filter.?

8.8, 8.9 and 8.10 are dependent on the setting of the volume control. On those measurements you are looking for a null so set the volume to get a reading of 8 or 9 to start with and adjust till those numbers drop to the lowest values. If you get good numbers on 8.7 above but minimal deflection at all volume levels on those three it means there is a problem in the audio chain somewhere after the IQ balance pot.?

The problem with no power output is usually associated with not getting all the enamel off L1,2, 3 or 4. And problems with L1-L3 can also affect the test signals used in the adjustments in the above paragraphs.?

73¡­ Ron

On Thu, Jan 26, 2023 at 18:42 Mark, WD4ELG <wd4elg@...> wrote:

Gary and Ron, thanks for the help; I greatly appreciate it.?

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Made some progress tonight:

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Took another look with DVM and magnifier at T1, and noted that several of the wires on T1 did not have solid contact due to enamel ¨C fixed!

Counted the turns on T1 and confirmed that I wired it for 40 meters, which matches the capacitors in the filter.

Powered up the unit and went into menu 8.7 for Peak BPF, and saw ? deflection/level.? C1 adjustment had no impact on the level, but I thought that since I had good indication that everything should be OK.

Went to menu 8.8 ?I-Q bal and saw a minimal deflection.

Went to menu 8.9 for Phase Lo and saw no deflection.

Went to menu 8.10 and saw no deflection.

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So everything should be good for initial alignment (according to my understanding).

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Hooked up the 40 meter dipole antenna and plugged in some earbuds¡­..nothing heard.? ARGH!

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Pressed down on the CW microswitch and listened on a separate receiver, no output signal heard.? ARGH!

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Went to menu #9 to use some of the test equipment.

Menu 9.3, value is 0 regardless of the RF gain knob setting.? Same with value for 9.4,? Not good.

Looking at page 104, section 5.1 of the Block diagram ¨C doesn¡¯t really help me much with further investigation.

Looking at page 105, the complete schematic looks impressive, but it also doesn¡¯t help me much with further investigation.

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So I am dealing with two separate issues:? CW microswitch is not activating transmit, and bigger issue is no audio output to the headphones.

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Ron, before I replace IC5 (because I am still seeing the same voltage values as before), I don¡¯t understand how this voltage would cause the issues I am seeing now.??

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(Not sure if Hans provides IC5 or if I should just order a new kit (is the QCX+ made with the same IC5?)

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Mark Lunday, WD4ELG
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