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4tone*25W IMD3 testing for circulator? - RF Cafe Forums
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| gangsway
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Post subject: 4tone*25W IMD3 testing for circulator?
Posted: Sat Jun 27, 2009 10:24 am
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Joined: Tue Nov 11, 2008
5:03 am
Posts: 16
Location: Shanghai, China
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I have a new design project for a circulator,which
request 4tone *25W IMD3. I can not understand it,
need your help regarding how to understnd, how to
set-up the testing bench, what's the testing solution
or idea? Appreciate!
_________________
glad to learn from you
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bhawkins |
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Post subject: Re: 4tone*25W IMD3 testing for circulator?
Posted: Wed Jul 22, 2009 4:26 pm
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Joined: Sun Feb 15, 2009
9:54 pm
Posts: 9 |
i doubt if there's any off the shelf solution, like
there is for 2-tones. i'd guess you would
use 3 2-way combiners; 3 low im circulators; several
low im bpf's; a spectrum analyzer all these components
have to have better im performance than what you're
designing i'm curious; why 4-tones? what
frequency? how low an im do you need?
bob hawkins
www.fairviewmicrowave.com
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nubbage |
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Post subject: Re: 4tone*25W IMD3 testing for circulator?
Posted: Fri Jul 24, 2009 3:25 am
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| General |
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Joined: Fri Feb 17, 2006
12:07 pm
Posts: 268
Location: London UK
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Hi gangsway
Bob is right: we need more info.
Just to give an example: If you have a situation
with 4 unmodulated carriers on fairly widely different
frequencies, such as across the UHF PMR radio band,
it is fairly straight forward to predict the third
order and 5th order IM frequencies that result when
all 4 pass through a non-linear system.
The fiendishly
difficult thing is to predict accurately what the
relative levels will be.
Pragmatically, I approached
this once by predicting the frequencies of the products
using simple software, and then used a Tuneable
Band Pass Filter to pick off each one. I then measured
each level with a calibrated high dynamic range
receiver, calibrated against an Agilent signal generator.
It was more laborious than using a Spectrum Analyzer,
but frankly the analyzer is more likely to generate
as much IMPs as the process you are studying.
Give us more data to work with.
_________________
At bottom, life is all
about
Sucking in and blowing out.
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gangsway |
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Post subject: Re: 4tone*25W IMD3 testing for circulator?
Posted: Tue Aug 11, 2009 10:34 pm
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Joined: Tue Nov 11, 2008
5:03 am
Posts: 16
Location: Shanghai, China
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Thanks very much.
I used four 8648C, plus 3 combiners,
NF and 8561E Spectrum analyzer to have the testing
done.
_________________
glad to learn from you
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