CMU200 erratic levels outside 1200-2200 MHz

[digitalrubbish]

Dear friends

I acquired a CMU200 for my HAM radio lab.  The unit however has an issue.  The generator works fine but the spectrum analyser shows about 16 dB too low from 0 till 1200 MHz and above 2200 MHz.  Between 1200 and 2200 all is fine.

Can anybody give me a hint what component could cause this.  I am not afraid of digging into the boards as R&S repair service is way beyond my budget.

Thanks for all help and schematics of the input boards or mixer boards where obviously this fault is located.


Pedro Wyns  ON7WP-AA9HX

direct mail to pedro.wyns@  the famous gmail dot com

[_Wim_]

Hi,

Just send you the service manual. A few questions:
- do you have the same results on both inputs?
- did you do a factory reset off all settings to be sure no correction table is loaded for the inputs (you can see this under "Connect Control" => "Ext. Att. Input" => "RX Connection Table"

[digitalrubbish]

I have this on all 3 inputs.

no correction table