Re: [help] Only noise being seen while IQ balance / phase lo / phase hi.

dl8lrz
 

Hi Jose,
i think:
first: IC10
PIN4 - connected to ground, must be 0V. Check why no 0V (bad solder joint, conductor path interrupted, measured correctly ??)
IC9:
PIN3 is 5V over 750k (r35). If PIN1 is roughly 5V, everything is ok.
IC9B, IC8, IC7, IC6, IC5:
The voltages depend on the voltage of the FST3153 (IC4, PIN7,9). It is best to measure whether IC5/IC7 PIN1 and IC9/PIN7 are ok. I think 2.5V is ok.
Conclusion:
The QCX noises, the volume can be adjusted with volume - So IC8-10 works first.
The voltages at IC6.7 suggest that IC5.6.7 also work (2,5V).
Align 8.1: Here about 7030kHz 8.2: 700Hz 8.3: 600Hz 8.4: 800Hz
8.7 Peak BPF: Press Select - loud tone must be generated. If only noise, then the path SI5351 - IC3C - filter T1 - FST3253 or CLK0 / CLK1 is disturbed
(many have faults on the connections T1). Only if a maximum is found with C1, then:
IQ balance: adjust with R27. If there is no minimum, the path BPF (T1) - FST3253 - IC5,6,7 or CLK0 / CLK1 is strongly asymmetrical or defective

If no balance tone is produced, check:
- Is the transmitter working? (use dummy!) -> test for IC1 and IC3
- Connect antenna, change frequency. Is some (weak) reception or just noise?

vy 73 Reiner DL8LRZ

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