Yes, after asking the question I tried the experiment and found no
difference. My concern was common mode pick up before the pre-amp not
so much insertion loss. If noise was going to be inserted in the
path, it would be much better for this to happen after the LNA for
obvious reasons.
Chris KQ6UP
On Wed, Jan 19, 2022 at 10:12 AM ko7i <ko7i@comcast.net> wrote:
>
> I manage a EMC test lab in the Seattle area. Typically we place a LNA pre-amp
> at the DRG Horn we use for Radiated RF Emissions measurements above 1GHz.
> Below 1Ghz, we place a pre-amp at our measurement receiver - not the antenna.
> Assuming a ham is using properly terminated double shielded CATV 75 ohm coax
> for the RX antenna, the insertion loss of the coax should be less than 2db
> for a 200 ft run. I find it hard to believe a ham would be able to "hear" the
> difference between pre-amp locations during real live operating conditions.
> If a ham wants to further improve the noise figure of their LNA, they would
> be well served by placing a bandpass filter, for the band of interest, at the
> front end of the pre-amp. Vy 73 de KO7I Sent from my Galaxy
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