Home |
Search |
Today's Posts |
|
#1
![]() |
|||
|
|||
![]()
Do you realize that 100dBm means o power output capability 10 10
MegaWatts? Even backing up 20 dB for improved linearity, not even the Voice of Ameirca will be able to compete with your LNA! I suggest you reformulate the question. then we'll be able to give you some answers. Saandy 4Z5KS |
#2
![]() |
|||
|
|||
![]()
Hi Saandy,
"+100dBm second order intercept" means that second order distortion products, following a simple small-signal second order model, would become equal to the input if extrapolated up to +100dBm. Second order products increase in dB amplitude exactly twice as fast as the fundamental, so that means that, say, a -10dBm input would produce an input-referred second harmonic of -120dBm, or -110dBc. If you decrease the input to -20dBm, the second harmonic drops to -140dBm, or -120dBc. If you increase the input to 0dBm, the second harmonic increases to -100dBm, which is also -100dBc. Extrapolating those numbers, you get a +100dBm second order intercept. In no way does it imply that the preamp (not all that low noise at a 10dB noise figure) can put out +100dBm, or can handle even +10dBm input without clipping or serious compression (though it would be nice in this case to get to close to that input level before clipping). Of course, distortion rises very quickly as you go into compression/clipping. Similarly, a +55dBm third order intercept implies third harmonic at -110dBm for a 0dBm signal. In other words, I'm looking for an amplifier that has about equally good second and third order distortion products for inputs near full scale. I don't want super-good TOI without also having second order products low. Cheers, Tom |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
![]() |
||||
Thread | Forum | |||
Preamp | Homebrew | |||
Need help installing internal preamp | CB | |||
5.070 distortion | Shortwave | |||
Antenna Preamp | Homebrew | |||
Optimod 8200 distortion problem | Broadcasting |