[Premium-Rx] Freds Book

[Nick Vafiadis]

Gents

Receiver IP3 should be quoted along with the receiver `noise figure

As the figure of merit is the difference between the noise and the IP3  
figure

You can increase a receiver IP3 performance by adding a pad to the input

for every 1dB of pad you increase the noise figure by 1dB and the ip3  
by 2dB

so you need to look for low noise and high 3IP

Even the latest DRS receivers struggle with this!


Definitions

Noise figure

Noise figure should be specified  across the band 2 MHz to 30 MHz.
The bandwidth used for calculating noise figure shall be 1 kHz, and
the noise figure calculation shall include internally generated noise
from all sources

LO Phase noise should be specified as below

-113  dBc/Hz SSB at and above 100 Hz offset.
-118 dBc/Hz SSB at and above 1 KHz offset.
-120 dBc/Hz SSB at and above 3 KHz offset.
-125 dBc/Hz SSB at and above 10 KHz offset.
-135 dBc/Hz SSB at and above 30 KHz offset.
-143 dBc/Hz SSB at and above 100 KHz offset
-157dBc/Hz SSB  at and above 1 MHz offset.
The minimum value of –154 dBc/Hz SSB shall be maintained for all  
offsets greater than 1 MHz.



Best regards
Nicolas Vafiadis
Director
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On 23 Mar 2010, at 00:10, Michael O'Beirne wrote:

>
> Gents,
>
> How does one actually measure an IP3 of +50dBm?  I haven't done the  
> sums but
> I suspect you'd need two power signal generators pushing out 10V PD  
> or so.
> At that sort of level how do you know that your combiner is linear?
>
> How do you prevent leakage?   Perhaps using LDF coax since ordinary  
> braided
> coax leaks too much.  How do you achieve decent isolation between the
> sources given that few combiners provide more than 40dB port to port
> isolation?
>
> You'd need a pretty robust attenuator as well.  I blew up two pi  
> sections in
> my Marconi TF2163S step attenuator by stupidly pushing through 10V  
> from an
> old R&S power genie.
>
> What would a receiver actually do with such inputs?  On most the  
> protective
> circuitry would kick in and provide about 50dB of isolation.
>
> I have tested IP3 to +33dBm with an 8640B and an R&S genie and it  
> was hard
> work to get reasonably accurate measurements in my amateur  
> unscreened "lab".
>
> What exactly is a "composite dynamic range"?  What are the elements  
> that
> form the "composite"?  It strikes me as being a pretty meaningless and
> undefined term.
>
> 73s
> Michael
> G8MOB
>
>
> ----- Original Message -----
> From: "dave shwarz" <n0sya at yahoo.com>
> To: <premium-rx at mailman.qth.net>
> Sent: Monday, March 22, 2010 11:23 PM
> Subject: Re: [Premium-Rx] Freds Book
>
>
>> Re Dentrea:
>>
>> High intercepts (+ 50 dBm), high composite spurious free dynamic  
>> range
>> (>150 dB), low phase noise (-186 dBc/Hz at 1KHz).
>>
>> That must be some fine rig.
>
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