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erikkaashoek
Negative value in NF measurement
Hi Erik, When I measure the NF of a wideband RF amplifier by the ULTRA , strictly according the procedure mentioned in the WIKI, I get negetive NF's as a result. First I measured the amplification per frequency by uing the LiteVNA. Please what could be wrong ? Jos
How much negative? NF measurement accuracy is for sure not better than +/- 0.5dB
Hello Erik, This is what I did :
- Measured the Amplifier usng the LiteVNA @ 100 MHz (gain 25.72dB) I used NanoVNA-App with a 20 db adaptor normalized.
- Connected 50 Ohms resistor to the RF connector of the TinySA-Ultra.
- Measured the NF of the Ultra (4.2dB)
- Stored that NF (result 0dB).
- Connected the amplifier between the 50 ohms resistor and th RF input.
- Measured the amplifiers NF (Result -5.2dB !!).
Am I doing somthing wrong ?
Best regards, Jos
This is weird, no, you are not doing anything wrong Let me try to replicate Erik
On Mon, Mar 20, 2023, 20:50 PA3CCE @.***> wrote:
Hello Erik, This is what I did :
- Measured the Amplifier usng the LiteVNA @ 100 MHz (gain 25.72dB) I used NanoVNA-App with a 20 db adaptor normalized.
- Connected 50 Ohms resistor to the RF connector of the TinySA-Ultra.
- Measured the NF of the Ultra (4.2dB)
- Stored that NF (result 0dB).
- Connected the amplifier between the 50 ohms resistor and th RF input.
- Measured the amplifiers NF (Result -5.2dB !!).
Am I doing somthing wrong ?
Best regards, Jos
— Reply to this email directly, view it on GitHub https://github.com/erikkaashoek/tinySA/issues/58#issuecomment-1476840462, or unsubscribe https://github.com/notifications/unsubscribe-auth/ABDIMRA5K3EBM6FDVQMLO4DW5CYHTANCNFSM6AAAAAAVPXFJ7U . You are receiving this because you commented.Message ID: @.***>