The SLP-50 filters which were on the 55 MHz lines have been replaced with the SBP-60. Their respective characteristics are given below:
| at 55MHz |
Insertion loss (dB) |
Return Loss (dB) |
| SLP-50 |
4.65 |
1.5 |
| SBP-60 |
1.36 |
23 |
SBP-60 has lower insertion loss and higher return loss.
This may however change the phase of I and Q in the demod boards and they will therefore need to be readjusted. Currently the output power level of 55 MHz demod is at 2dBm, whereas it ought to be at 6dBm. I have not yet corrected that. Once that is completed Kiwamu will adjust the phases.
I shifted the temperature sensor to a new location. See the photograph below. I noticed that the higher temperature is reached on the side where there are two RF Amps. So it would be better to check the temperature of that area and make sure that it remains well below 65 deg. The operating maxium is 65deg C
Here is a picture of the new RF source layout.
And here is a photograph of it
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