What the first?

[michaelscoofield]

Hello,

I would like to ask kindly for your opinion.

If the Air band monitoring setup needs amplifying ...what do you prefer at first after the antenna > Amp then Bandpass filter or filtering first and then amplifying it?

Thanks for comments and experiences.

-m

 

[dispatchgeek]

I've always filtered before the amp. That way the filter doesn't have to knock down amplified noise.

 

[michaelscoofield]

I've always filtered before the amp. That way the filter doesn't have to knock down amplified noise.

Many thanks. I have the same idea. Just wanted to ask and learn more about it.
-m

 

[dlwtrunked]

I've always filtered before the amp. That way the filter doesn't have to knock down amplified noise.

More precisely ... "That way the filter does not have to knock down amplified signals out of the desired band." (Those are not noise in the technical sense.)

 

[michaelscoofield]

Many thanks, understand.

Also, could you recommend where I should (at best) insert the VHF FM band stop filter, please?
Current config is: Antenna at 11m on the roof > Airband BPF at its feed point > Switchable pre-amp then after > LMR400 coax down to shack.

-m

 

[michaelscoofield]

Could be ok to put the FM band stop filter in line with the Airband filter at the antenna feed point?
Maybe the way is to put this band stop filter in front of receiver to eliminate also some unwanted signals from FM band
coming to the coaxial cable due to its imperfect shielding penetration...?