[Lowfer] WSPR Weak Sig vs. QRP

[Pat Bunn]

I fully understand that the R75 is not a strong performer with regard to IMD. That is the main reason I am only using it as an IF . With a Clifton Labs probe as an antenna with its excellent  IMD performance followed by a strong up converter the R75 is not significant in the system with regard to front end IMD performance as long as it is properly adjusted.

Pat

Pat

Eric NO3M <no3m at no3m.net> wrote:

>Regarding receiver specs, a few examples for Third-order dynamic range 
>of some receivers cited by LF/MF ops and a couple additional for comparison:
>
>R-75 67 dB @ 5 KHz
>TR-4C 68 dB @ 2 KHz
>JRC-525 72 dB @ 5KHz
>IC-706MK2G 74 db @ 2 KHz
>Collins R-390A 79 dB @ 2 KHz
>Elecraft K2 80 dB @ 2 KHz
>Flex1500 88 dB @ 2 KHz
>Flex3000 90 dB @ 2 KHz
>Elecraft K3 95 dB @ 2KHz
>Flex 5000 96 dB @ 2 KHz
>Perseus 99 dB @ 2 KHz
>Elecraft KX3 104 dB @ 2 KHz (w/ roofing filter)
>
>While the R-75 may have good "sensitivity" at LF/MF, it is rather poor 
>for in-band strong signal handling, on par with a Drake TR-4C (my first 
>HF rig).
>
>Full list: http://www.sherweng.com/table.html
>
>And of course, upconverter quality will effect the performance of those 
>rigs that need one.
>
>73 - Eric NO3M, WG2XJM
>
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