Formulas & Data:
- Electronics
- Mathematics
- Physics
- RF & Microwaves

Parts Vendors:
- all hand-selected

- Amateur Radio
- Vintage Articles:
- Electronics World
- Popular Electronics
- QST
- Radio & TV News
- Radio Craft
- Short Wave Craft
- Wireless World

- Events Calendar
RF Cafe Homepage
Copyright 1999-2015   •−•  ••−•    −•−•  •−  ••−•  •   "RF Cafe" in Morse Code  >> Listen to It <<
- EW & Radar Handbook
- Quizzes       - Software
- App Notes
- Calculators
- Advertise on RF Cafe
- About RF Cafe™
- RF Cafe Shirts & Mugs
- RF Cafe Archives
RF Cafe Book Contest
- RF Cafe on Visit RF Cafe on Facebook Visit RF Cafe on Twitter Visit RF Cafe on LinkedIn
- Tech Humor
- Forums Archive
- Job Board
- Donate to RF Cafe
- Kirt's Cogitations
Custom Search
More than 10,000 searchable pages indexed.
Greetings: There is so much good stuff on RF Cafe that there is no way to list or link to all of it here. Please use the Search box or the Site Map to find what you want - there is a good chance I have it here. Thanks!

Image anf IF rejection - RF Cafe Forums

Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views. It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if you would like to post something on RF Cafe's Facebook page, please do.

Below are all of the forum threads, including all the responses to the original posts.


jab
Post subject: Image anf IF rejection Posted: Thu Mar 23, 2006 1:24 pm

Lieutenant

Joined: Wed Mar 08, 2006 8:18 am
Posts: 3
Guys - any idea on how to measure the image frequency and IF rejection ratio say your in band is 98MHz.

Thanks.
JAB


Top

yendori
Post subject: Posted: Thu Mar 23, 2006 5:05 pm

General


Joined: Thu Sep 25, 2003 1:19 am
Posts: 50
Location: texarcana
Measure your desired IF signal. Apply the image frequency at the input and then measure the image IF.

RK


Top

nubbage
Post subject: Image anf IF RejectionPosted: Fri Mar 24, 2006 11:18 am

General


Joined: Fri Feb 17, 2006 12:07 pm
Posts: 218
Location: London UK
More specifically if the IF is 10.7MHz, then set the sig gen to 98MHz and note a reference level immediately after the IF filter stage. Avoid taking a level any further down the IF chain, as the presumably FM receiver will have a nonlinear limiter.

Set the generator frequency to 21.4 MHz above or below the 98MHz channel, eg 76.6MHz and increase the level of the generator until it reaches the previous level. Note the attenuator level setting difference. This is the Image Rejection ratio in dB

Set the generator to 10.7MHz and repeat the measurement. The attenuator difference is the IF rejection.

All best
Trev


Top

jab
Post subject: Posted: Tue Apr 04, 2006 8:54 am

Lieutenant

Joined: Wed Mar 08, 2006 8:18 am
Posts: 3
Thank you Guys.
I dont have the attenuator so this is what I did.
First measure the direct inject sensitivity at operating freq. and inject the image - the difference is my ratio. same thing on 10.7MHz for IF.

Thanks again.
JAB



Posted  11/12/2012

Your RF Cafe
Progenitor & Webmaster

Click here to read about RF CafeKirt Blattenberger… single-handedly redefining what an engineering website should be.

View the YouTube RF Cafe Intro Video Carpe Diem!
(Seize the Day!)

5th MOB: My USAF radar shop

Airplanes and Rockets: My personal hobby website

Equine Kingdom: My daughter Sally's horse riding website