[hpsdr] NOISE FLOOR

[Jim Sanford]

This is my experience.

I just ran a test:  My noise floor on 10 meters went up 20db when I 
connected an antenna.

I do NOT think that I am receiver noise-figure limited.

Remember that too much gain ahead of the front end degrades third-order 
intercept, etc.

73,

Jim

wb4gcs at amsat.org


On 1/17/2019 10:27 PM, Byron Engler wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
>
> Hi All,
> I was under the impression that the effective received noise from a 
> real antenna in average conditions (on HF bands) contributes  more 
> noise than the front end amplifier, so installing fancier preamps, in 
> general, wont have much of a performance gain.
>
> 73
> Byron
> ZL3DXT
>
> On Fri, Jan 18, 2019 at 4:10 PM Bob Stricklin <bstrick at n5brg.com 
> <mailto:bstrick at n5brg.com>> wrote:
>
>     ***** High Performance Software Defined Radio Discussion List *****
>
>     Take a look at these: https://www.sv1afn.com/j310preamp.html,
>     http://advancedreceiver.com/page5.html for 28 MHz and up.
>     Bob N5BRG
>
>>     On Jan 17, 2019, at 8:33 PM, Scott Traurig
>>     <scott.traurig at gmail.com <mailto:scott.traurig at gmail.com>> wrote:
>>
>>     Bob,
>>
>>     Do you have a suggestion for an HF preamp with better NF performance?
>>
>>     73,
>>
>>     Scott/w-u-2-o
>>
>>
>>     On Thu, Jan 17, 2019 at 9:12 PM Bob Stricklin <bstrick at n5brg.com
>>     <mailto:bstrick at n5brg.com>> wrote:
>>
>>
>>         DC6NY’s comment about the first amp setting the NF is correct
>>         and the reason people add their own external preamp with
>>         better specs to improve performance. The NF of 6dB reported
>>         by W-U-2-O is high and can be improved adding a preamp which
>>         will become the first amp.
>>
>>         Bob N5BRG
>>
>
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