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 Thank you for visiting RF Cafe!

Module: My Reflection Sucks - 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


Who Are We Afraid Of?
God 0% [ 0 ]
Evil 0% [ 0 ]
Bin Laden 0% [ 0 ]
Ourselves 100% [ 1 ]
Total votes : 1
Author Message
Kirt Blattenberger
Post subject: module: My Reflection Sucks Posted: Tue Mar 21, 2006 8:33 pm

Site Admin


Joined: Sun Aug 03, 2003 2:02 pm
Posts: 308
Location: Erie, PA
NOTICE: I replicated the post of user "module" while moving it to the database on the new server. - Kirt Blattenberger

Posted: 21 Mar 2006 06:28 pm Post subject: My Reflection Sucks

--------------------------------------------------------------------------------

Hello Everyone,

I have been a good person and tried to design my PA around my load line. Our establishment has this bad habit of "just dropping transformers in". I would actually like to try to match my input impedance using that stuff called math. I have calculated my loadline and designed my transformer using UT-34-50 semi rigid coax. Can someone do a quick check on my equations? I hooked it up to my network analyzer and I get nasty reflection. I am trying to match the input of a Polyfet SQ721 to a 50Ohm source. I am using Amawave's UT-34-50 50Ohm semi-rigid coax with a Amidaon BN-61-2402 with an AL=150. My math is here done in Mathcad. Any feedback would be greatly appreciated.

http://www.geocities.com/ldmosvsvdmos/Mathcadsq721.pdf
http://www.geocities.com/ldmosvsvdmos/Mathcadsq721.

_________________
- Kirt Blattenberger
RF Cafe Progenitor & Webmaster


Top

fred47
Post subject: ReflectionPosted: Wed Mar 22, 2006 8:53 pm

General


Joined: Wed Feb 22, 2006 3:51 pm
Posts: 104
Hi!

I guess I'm not clear on what you're doing.

A quick trip to a Smith chart, matching 50 Ohms to 10-j65 Ohms at 88 MHz, yielded a two-inductor matching solution. One inductor of 45 nH from the amplifier input to ground, and a 83 nH inductor from the amplifier input to the power FET gate. I'm assuming the source is grounded.

In 45nH
o--UUUU-----------| gate
`````````````|
o----------UUUU-
Gnd ``` 83 nH

(ignore the ` characters - PHPBB doesn't let me use spaces for ascii art - which I'm not good at anyway!)

Maybe that's not what you meant. Maybe you meant something like the series 45 nH inductor, with a shorted stub of about VF*10 inches of 50 Ohm coax in parallel (in place of the 83 nH inductor)?

Or did you mean a 1:5 transformer, with approximately 517 nH inductor in series with the input winding?

It doesn't look like I'm "getting it". What configuration is your input matching network? Are we even "on the same page"?

Thanks!
Fred



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
Webmaster:
Kirt Blattenberger,
 BSEE - KB3UON

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:
 AirplanesAndRockets.com

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

height-line