Antenna gain works as expected on 20m but when using the Flex 6700 in 630m to try to decode JT9 I ran into an odd behavior. +30dB Gain increases noise and artifacts on the band, then +40dB goes down again. I recorded it on a video, maybe someone can explain. Is this normal?
RF gain is not effective on the lower frequencies where the noise is higher and you are noise limited at the antenna. At those frequencies, you should never have to use the preamp. At +40 dB you are adversely affecting the ADC.
I understand that Tim, but I am surprised by the behavior. At +20dB it goes up considerably to then go down at +30 and +40dB. Also, while I will never use gain on those frequencies with a dipole or any antenna with any gain, I am testing different settings with a magnetic loop and I have seen some interesting improvements in 160m with +10dB vs 0dB.
Anyway, I just didn't expect the behavior... can you confirm it is the natural one? Maybe my 6700 is due a factory reset.