On Wed, Sep 18, 2019 at 04:34 PM, Andy G0FTD wrote:
If we also consider a previous statement that the input amp is best measure
with the correct load,why was there no difference between
doing a calibration routine with a SHORT or an OPEN with regards to the noise
floor ?
Just performed test. I disconnected PC to avoid interference and performed measurement from the battery.
SHORT load on CH1: noise floor almost -50 dB above 600 MHz
OPEN load on CH1: noise floor -55..-60 dB
No load on CH1: almost the same as OPEN load
50 ohm load on CH1: noise floor below -70 dB up to 900 MHz
So, the SHORT terminator has most worse case
OPEN terminator is better than SHORT, but worse than 50 ohm.
The best result acheived with 50 ohm terminator on CH1.
It is 10 dB betten than OPEN load and 20 dB better than SHORT load.
