[hpsdr] QSD gain and noise.

[Ramakrishnan Muthukrishnan]

On 9/23/07, Phil Harman <phil at pharman.org> wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
>
> In reply to Ahti and Frank,
>
> Ahti, from memory the NF measurements you suggest are a little high but in
> the right ball park. The problem of connecting the Janus balanced inputs

Hi Phil and the group,

Sometime back I created a spreadsheet, mainly for me to learn about
the cascaded analysis for designing the Phoenix gain. I am attaching
the spreadsheet. I found an NF of 19.44 for the Janus ADC. Also the
spreadsheet shows that for 6m, we need a min gain of around 7 dB. But
this analysis ignores the effects of QSD switch switch on/off timing
issues etc associated with operating them on higher frequencies.

Please have a look at the attached (gzipped) spreadsheet. I still
haven't completely understood a way to
create a noise figure calculations for an Opamp differential
amplifier. Marco has a spreadsheet to do that.

73
Ramakrishnan, vu3rdd
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