[Premium-Rx] Freds Book

[Michael O'Beirne]

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.