Thank you for visiting RF Cafe! Electronics World Cover,TOC,and list of posted Popular Electronics articles QST Radio & TV News Radio-Craft Radio-Electronics Short Wave Craft Wireless World About RF Cafe RF Cafe Homepage RF Cafe in Morse Code Google Search of RF Cafe website Sitemap Electronics Equations Mathematics Equations Equations physics Manufacturers & distributors Engineer Jobs Twitter LinkedIn Crosswords Engineering Humor Kirt's Cogitations Engineering Event Calendar RF Engineering Quizzes AN/MPN-14 Radar 5CCG Notable Quotes App Notes Calculators Education Magazines Software,T-Shirts,Coffee Mugs Articles - submitted by RF Cafe visitors Simulators Technical Writings RF Cafe Archives Test Notes Wireless System Designer RF Stencils for Visio Shapes for Word Search RF Cafe Sitemap Advertising Facebook RF Cafe Forums RF Cafe Homepage Thank you for visiting RF Cafe!

4Tone*25W IMD3 Testing for Circulator? - RF Cafe Forums

The original RF Cafe Forums were shut down in late 2012 due to maintenance issues. Original posts:

Amateur Radio | Antennas | Circuits & Components | Systems | Test & Measurement

 Post subject: 4tone*25W IMD3 testing for circulator?
Posted: Sat Jun 27, 2009 10:24 am 

Joined: Tue Nov 11, 2008 5:03 am
Posts: 16
Location: Shanghai, China
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

 Post subject: Re: 4tone*25W IMD3 testing for circulator?
Posted: Wed Jul 22, 2009 4:26 pm 

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

 Post subject: Re: 4tone*25W IMD3 testing for circulator?
Posted: Fri Jul 24, 2009 3:25 am 
User avatar

Joined: Fri Feb 17, 2006 12:07 pm
Posts: 268
Location: London UK
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.

 Post subject: Re: 4tone*25W IMD3 testing for circulator?
Posted: Tue Aug 11, 2009 10:34 pm 

Joined: Tue Nov 11, 2008 5:03 am
Posts: 16
Location: Shanghai, China
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

Posted  11/12/2012

RF Cafe Software

   Wireless System Designer - RF Cafe
Wireless System Designer

RF & EE Symbols Word
RF Stencils for Visio
Calculator Workbook
RF Workbench
Smith Chartâ„¢ for Visio
Smith Chartâ„¢ for Excel

About RF Cafe

Kirt Blattenberger - RF Cafe WebmasterCopyright
1996 - 2022
Kirt Blattenberger,

RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The Internet was still largely an unknown entity at the time and not much was available in the form of WYSIWYG ...

All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.

My Hobby Website:

Try Using SEARCH
to Find What You Need. 
There are 1,000s of Pages Indexed on RF Cafe !