RIGOL Technologies (test equipment) - RF Cafe
LadyBug Technologies LB480A RF Power Sensor Connectors - RF Cafe
 

About RF Cafe

Kirt Blattenberger - RF Cafe Webmaster

Copyright: 1996 - 2024
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 World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

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

Electronics World articles Popular Electronics articles QST articles Radio & TV News articles Radio-Craft articles Radio-Electronics articles Short Wave Craft articles Wireless World articles Google Search of RF Cafe website Sitemap Electronics Equations Mathematics Equations Equations physics Manufacturers & distributors Engineer Jobs LinkedIn Crosswords Engineering Humor Kirt's Cogitations RF Engineering Quizzes Notable Quotes App Notes Calculators Education Engineering magazine articles Engineering software Engineering smorgasbord RF Cafe Archives RF Cascade Workbook 2018 RF Symbols for Visio - Word Advertising RF Cafe Homepage Thank you for visiting RF Cafe!
Anatech Electronics (RF Filters) - RF Cafe

Freescale MRF transistor - RF Cafe Forums

RF Cafe Forums closed its virtual doors in 2012 mainly due to other social media platforms dominating public commenting venues. RF Cafe Forums began sometime around August of 2003 and was quite well-attended for many years. By 2010, Facebook and Twitter were overwhelmingly dominating online personal interaction, and RF Cafe Forums activity dropped off precipitously. If the folks at phpBB would release a version with integrated sign-in from the major social media platforms, I would resurrect the RF Cafe Forums, but until then it is probably not worth the effort. Regardless, there are still lots of great posts in the archive that ware worth looking at.

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

-- Amateur Radio
-- Anecdotes, Gripes & Humor
-- Antennas
-- CAE, CAD, & Software
-- Circuits & Components
-- Employment & Interviews
-- Miscellany
-- Swap Shop
-- Systems
-- Test & Measurement
-- Webmaster

Corvus
Post subject: Freescale MRF transistor Posted: Fri Oct 05, 2007 9:19 am

Captain


Joined: Mon Jul 18, 2005 12:55 pm
Posts: 8
Geetings!

I am experiencing the sudden death of lots of PA pallets mounted with MRF377 transistors. Anyone else with the same problem? I am just wondering if its my own problem or in fact is an inherent problem with this kind of transistor. People said is better to change to NXP. Why? Any solution finded with MRF?

Cheers!


Top

IR
Post subject: Posted: Fri Oct 05, 2007 3:04 pm

Site Admin


Joined: Mon Jun 27, 2005 2:02 pm
Posts: 373
Location: Germany
Greetings Corvus!

You are not the only one!

A while ago I was working on a PA design which was made of MRF374, and MRF377. I had the same problem with this series of transistors. Although, as far as I recall, the problem was with the MRF374.

In my case the problem was that MRF374 was used to drive another MRF374 and the amount of input power to the second MRF374 was too high. This series of transistors doesn't have a device with an intermediate output power level in the range of 60-80W in contrast to the UMTS line where the variety of devices is much larger: MRF21010, MRF21030, MRF21045, MRF21060, MRF21090....

The problem in essence has to do with a protection diode that is located between the Gate and Source. This diode is meant to protect against reverse voltages. The malfunction happens during a high voltage RF swing, which causes the diode to clamp the negative part of the cycle, as a result, a short-circuit is caused between the Gate and Source. I had to change a lot of transistors until I switched to another manufacturer.


Top

Corvus
Post subject: Posted: Mon Oct 08, 2007 5:56 am

Captain


Joined: Mon Jul 18, 2005 12:55 pm
Posts: 8
Hi IR!

I appreciate your help!I want to change the manufacturer of my transitors but I can not find another PA pallet implemented with other transistor.Do you know any manufacturer that implements pallets of powers of 50Wrms or 100Wrms but without Freescale transitors?


Top

IR
Post subject: Posted: Mon Oct 08, 2007 6:16 am

Site Admin


Joined: Mon Jun 27, 2005 2:02 pm
Posts: 373
Location: Germany
I think that NXP do that.

I will also check other manufacturers for you. Unforutnately, I am already long time out of the PA arena.


Top

Corvus
Post subject: Posted: Mon Oct 08, 2007 11:30 am

Captain


Joined: Mon Jul 18, 2005 12:55 pm
Posts: 8
Hi again,

Anybody knows how to avoid or short circuit the diode protection in the MRF transistor? Is it possible?

thanks


Top

IR
Post subject: Posted: Mon Oct 08, 2007 1:51 pm

Site Admin


Joined: Mon Jun 27, 2005 2:02 pm
Posts: 373
Location: Germany
As far as I know, the only way is to provide the required input power so that the diode will not go into operation. Once the diode is clamped it is too late.

Look in the device data sheet what is the allowed input power level and don't go over it.

I hope this helps.







Posted  11/12/2012
Copper Mountain Technologies - RF Cafe
Werbel Microwave - RF Cafe
RF Cascade Workbook 2018 by RF CafeCafe
 

Please Support RF Cafe by purchasing my  ridiculously low−priced products, all of which I created.

These Are Available for Free