Re: LF: Pre amp *after* BPF??

[Chris Wilson <dead.fets@gmail.com>]

Hello Andy,

OK,  thanks  for that Andy.  I can see one future snag though, if I use both
"aerial"  ports  on  the  Red  Pitaya and an antenna splitter so I can
receive  LF  and MF at the same time, I will need two pre amps, one on
each  port,  as  putting a single one between aerial and input port of
splitter  will mean any BPF is AFTER the pre amp... Not a huge deal as
I have two pre amps, but I am guessing that's what i will have to do?


Friday, March 16, 2018, 11:54:09 AM, you wrote:

> After, definitely


> Before is applicable to VHF and up where equipment noise figure
> dominates sensitivity and a filter in the antenna side wold add loss and 
> degrade overall NF


> At HF and certainly LF, atmos noise dominates to noise figure is
> unimportant.   That way you get the benefit of rejecting strong OOB
> signals that may stress even the preamplifier


> 'jnt





-- 
Best regards,
 Chris                            mailto:dead.fets@gmail.com