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!

Ampifier Test Setup Procedure - 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: ampifier test setup procedure
Posted: Mon Oct 22, 2007 7:41 am 
User avatar

Joined: Thu Oct 11, 2007 7:58 pm
Posts: 4

When testing an amplifier I was told to connect dc, turn dc on and then connect testing cables. Is this the right procedure?


 Post subject:
Posted: Tue Oct 23, 2007 3:22 pm 
User avatar

Joined: Sun Mar 19, 2006 5:25 pm
Posts: 23
Location: Burnaby
I don't think this procedure fits for all the amplifiers such a high power one. You may check the specification of your instrument to ensure it.

 Post subject:
Posted: Wed Oct 24, 2007 7:33 am 
User avatar

Joined: Fri Feb 17, 2006 12:07 pm
Posts: 268
Location: London UK
Feng is right: many medium to high power amps have a stability margin that is both source and load sensitive: that is they become unstable at certain load and source combinations of Reflection Coefficient magnitude and phase. I think a dude called Linvill first did the analysis of this for soldstate amps.
If the test cables are long and/or have extremely good dielectric insulation, it is possible that static charge can build up between the centre and outer. It therefore good practice to short the test cable between inner and outer before connecting the cables to the amp. Having connected them without risk of static damage, I would next turn the DC power on having ensured the source and load have a reasonably good match.

 Post subject:
Posted: Sun Jan 27, 2008 3:36 am 
Site Admin
User avatar

Joined: Mon Jun 27, 2005 2:02 pm
Posts: 406
Location: Germany
Hello Asaf,

Since I also come from Israel and have worked in several RF companies,
I know the root of the fairy tale instruction you were told:

It is the fear that there might be an input power applied to the amplifier before power supply is applied, namely when the amplifier is connected as part of a cascade. When several amplifiers are connected in cascade that is the right thing to do but NOT when testing an amplifier as a stand alone unit.

What the other posts mentioned is 100% correct.

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 !