[Premium-Rx] Freds Book

[Jack Smith]

I can measure IP3 at the +45 dBm level and IP2 not too far from +90 dBm. 
It requires a decent combiner, some attenuators, 1 watt power amplifiers 
and judicious use of attenuation in the spectrum analyzer input, 
combined with narrow bandwidth. I had to do this when developing my 
Z1501D active antenna, which has performance in this range.

I've written about the test setup I use to measure these levels of 
IP2/IP3 at:
http://www.cliftonlaboratories.com/Documents/Measuring%20%202nd%20and%203rd%20Order%20Intercepts%20of%20the.pdf

If you have trouble with that link, try:
http://www.cliftonlaboratories.com/z1501_active_antenna.htm

My Z1501D measurements have been verified by two independent reviewers 
and we all agree within a dB or two.

Jack


On 3/22/2010 7:10 PM, 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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