Electronics > Repair
CMU200 Rx level issue / failed loop test
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_Wim_:

--- Quote from: Sas on January 21, 2022, 09:33:36 am ---Congratulations on the repair :-+. Can you do the 1-> 4 and 3-> 2 loop test with a positive result?

--- End quote ---

A single frequency fails on the TX1 => RX4. But this is related to CH1 of the frontend, which was a separate issue as reported in the first post (and as far as I remember, CH1 has always been a less good performer since I have the CMU). I typically do not use CH1, so I never looked into this.

There does seem to be a small jump (+-0.6dbm) when switching IF-frequencies, but will try to fix that with the frequency dependent attenuation settings
_Wim_:

--- Quote from: _Wim_ on January 21, 2022, 07:05:42 pm ---There does seem to be a small jump (+-0.6dbm) when switching IF-frequencies, but will try to fix that with the frequency dependent attenuation settings

--- End quote ---

A little better
_Wim_:
Meaured spectrum of a BG7TBL RF noise source (https://www.epanorama.net/blog/2017/08/29/bg7tbl-rf-noise-source/)

No strange jumps or peaks, so I expect most is working fine, certainly sufficient for my modest needs in RF (my low cost China RF cables and connectors are probably creating at least as much deviations...)
Sas:
I fixed the CMU.. The CMU passes all tests without errors, including the 1-> 4 / 3-> 2 loop test. Adds the RF3 OUT -> RF2 loop test image from FreRes after repairing the RF3 output and replacing the 836 MHz BHD filter  :)
_Wim_:

--- Quote from: Sas on January 24, 2022, 09:30:50 pm ---I fixed the CMU.. The CMU passes all tests without errors, including the 1-> 4 / 3-> 2 loop test. Adds the RF3 OUT -> RF2 loop test image from FreRes after repairing the RF3 output and replacing the 836 MHz BHD filter  :)

--- End quote ---

Congratulations. Looks very good! Can you post a picture how you installed the BHD filter?
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