| Electronics > Repair |
| CMU200 Rx level issue / failed loop test |
| << < (13/15) > >> |
| Ringmodulator:
Hi, my unit seems to have the same poblems. Can someone point me to a source for these filters, which delivers to Germany? Chris |
| _Wim_:
--- Quote from: Ringmodulator on February 12, 2023, 03:07:46 pm ---Hi, my unit seems to have the same poblems. Can someone point me to a source for these filters, which delivers to Germany? Chris --- End quote --- For the 836MHz part, Arrow electronics as listed above: https://www.arrow.de/products/search?q=B39841B4147U410++&r=true |
| DavidAzulay5000:
progress report The filter 1842.5MHZ Works perfectly B39182-B4139-U410 1842.5MHz SAW Filter 50 Ohm SMD In addition there was a problem with the 9DB attenuation filter So I made a filter from three size 0402 resistors t filter 2 24 ohms 1 47ohm In addition the RF SPDT SWITCH UPG2179TB was broken So I looked for a replacement in other devices I found the component on the WIFI board of XBOX 360 E I removed it and replaced it The problem remained in the 836.5MHZ filter from the Data Sheet I think the problem is that the attenuation is too high at frequencies from 1200 MHz to 2000 MHz The TYP attenuation It is over 50DB And that's why there is a failed internal loop test Frequency 1200 to 2200 All other frequencies with an accuracy of 0.3 dB the 1842.5mhz filter of epcos is perfect B39182-B4139-U410 1842.5MHz SAW Filter 50 Ohm SMD I do not recommend purchasing the EPCOS 836.5MHZ filter model B39841-B4122-U410 836MHz SAW Filter SMD I tried to replace about 4 units with the input and output polarity changed Exactly the same results in all the tested filters regardless of the polarity of the filter I thought the minimum attenuation . Maybe you will fall on one of the filters being tested But they were all measured the same. |
| _Wim_:
--- Quote from: DavidAzulay5000 on February 16, 2023, 07:17:24 am ---The problem remained in the 836.5MHZ filter from the Data Sheet I think the problem is that the attenuation is too high at frequencies from 1200 MHz to 2000 MHz The TYP attenuation It is over 50DB And that's why there is a failed internal loop test Frequency 1200 to 2200 --- End quote --- Not sure if I misunderstood you, but the goal of this filter is to ONLY allow 836.5MHz to get through (the fixed frequency filter in the attached block diagram), all other frequencies must be attenuated as much as possible. So attenuation can only be too high at 836.5MHz, at other frequencies, it must be as high as possible. (block diagram copied from here: https://electricalworkbook.com/spectrum-analyzer/) |
| _Wim_:
--- Quote from: DavidAzulay5000 on February 16, 2023, 07:17:24 am ---progress report --- End quote --- Do you have an SDR dongle (or other spectrum analyzer) to check if something arrives at the filter (like I have done here: https://www.eevblog.com/forum/repair/cmu200-rx-level-issue-failed-loop-test/msg3917207/#msg3917207)? My best guess is some RF-amplifier or RF-switch if broken upstream, certainly as you already had to replace another switch in the unit. |
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