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dbostrom
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U.FL versus MMCX connectors (or, why go microscopic?)

Mon Dec 05, 2005 5:43 pm

Rant about connectors here.

U.FL connectors are touted as "the world's smallest" coaxial connectors. This is just fine for teeny-weeny applications such as the guts of a cell phone or when packed into a laptop but not so great for applications on a more normal physical scale and especially those that may require multiple insertions/removals in possibly less-than-ideal circumstances, such as 80' up a tower.

The insertion/removal problem is exacerbated when vendors of equipment offering the option of field changeouts do not also offer the manufacturer-specified connector removal tool. For instance, Hirose specifies that removal tool U.FL-LP-N-2 be used when disconnecting their U.FL connectors in order to avoid damaging either the plug or (worse) jack. Any damage will result in erratic performance of the connector. It is indeed extremely easy to damage these connectors when the removal tool is not used.

Casual removal and insertions of U.FL connectors should be avoided even with the proper tool as the manufacturer's stated total insertion/removal life is only 30 cycles.

When it comes to maneuvering the cable attached to a mated U.FL connector, extreme caution should be used. Acceptable torsion and bending forces on U.FL connectors are just as microscopic as their size, on the order of 2 N.

Shorter version: U.FL connectors are misapplied in the situation of equipment that is routinely accessed and disassembled.

We read on this forum many instances of mysteriously underperforming links, "defective" pigtails, etc. when in fact if we believe the specifications and application notes of U.FL connector manufacturers we're instead seeing exactly what may be expected in a misapplication context. Put another way, the statistical chance of a population of U.FL connectors surviving fully intact the results of the field realities we face is about zero.

Sadly, in the case of CM9 cards we're stuck with a connector that's inappropriate for the applications in which most readers of this forum are using these cards. CM9 cards are supplied only with the wrong connector.

Minipci wlan cards designed and offered for the WISP market and in particular base station equipment can and should offer better connector options.

For instance, the electrical performance of MMCX connectors is slightly better than that of U.FL, the insertion/removal lifetime is over ten times (500) that of U.FL and the mechanical strength is described by Hirose as "rugged", with no precautionary application notes about torsion and bending forces. The simple fact that Hirose does not offer a removal tool for MMCX connectors is a powerful clue about their relative durability.

SMA connectors are even better in this regard, being as they are "real" connectors w/threaded mating surfaces and mechanical strength far above that of U.FL or MMCX connectors.

So, Mikrotik and anybody else with enough oomph to perhaps influence manufacturers of wlan cards, please suggest that CM9 and equivalent cards be offered with connectors appropriate for our application. If you sell a router equipped w/cards better suited for our market, such as the SR5, please send them equipped with MMCX pigtails so we can remove and throw away the useless U.FL connectors now in our RB products. Also, you might consider offering the U.FL removal tool U.FL-LP-N-2 as an accessory. :D

Thank You and this concludes my rant. :shock:

References:

MMCX
http://www.hirose.co.jp/cataloge_hp/e33900017.pdf

U.FL
http://www.hirose.co.jp/cataloge_hp/e32119372.pdf

Edit:

The proper removal tool for U.FL connectors can be ordered from Digikey as Digikey part number H9159-ND, $24.11 US.
 
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jp
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Mon Dec 05, 2005 6:23 pm

I second that. Almost any connector is nicer than U.FL. I like MMCX as well.
 
vlatko
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Tue Dec 06, 2005 3:44 am

its all about manufacturing costs :)
 
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stephenpatrick
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Tue Dec 06, 2005 11:25 am

Suggestion:

MT, consider this for one of the 2 connectors on the next run of your own-brand R52 cards -

I'm sure a lot of people would pay if there is a performance or reliability increase. U.FL is really not suited to the job.

Regards
CableFree - Wireless Excellence - Microwave, E-band Radios, Free Space Optics, High performance Radios & Routers
http://www.cablefree.net
 
NZLamb
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Tue Dec 06, 2005 10:00 pm

Agreed, this is one reason why I like the SR cards with their MMCX connectors. They also have RP-SMA as an option but sadly I haven't any suppliers offering these yet.
 
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Sun Dec 11, 2005 2:45 am

Hi, if i use an mmcx conector on SR cards, should i change antenna-mode to b?
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cibernet
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Sun Dec 11, 2005 5:49 am

uFn sucks... i have test them, and I have much more streght with MMCX...
José Ignacio Acosta
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NZLamb
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Sun Dec 11, 2005 9:06 pm

Hi, if i use an mmcx conector on SR cards, should i change antenna-mode to b?
Yes
 
Hellbound
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Sun Dec 11, 2005 10:31 pm

Hi, if i use an mmcx conector on SR cards, should i change antenna-mode to b?
Yes

then sr2 also sucks in that matter, 11b is outdated and stupid.
 
NZLamb
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Sun Dec 11, 2005 10:35 pm

Not at all; RouterOS refers to the two antenna connectors on wireless cards as A and B. All he asked is which antenna needed to be enabled in RouterOS to use the MMCX connector, which is antenna B. This has nothing to do with the speed the card operates at.
 
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macsrwe
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Re: U.FL versus MMCX connectors (or, why go microscopic?)

Sun Mar 06, 2011 12:15 am

U.FL connectors are... not so great for applications on a more normal physical scale and especially those that may require multiple insertions/removals in possibly less-than-ideal circumstances, such as 80' up a tower...

The simple fact that Hirose does not offer a removal tool for MMCX connectors is a powerful clue about their relative durability.
I'm a big fan of MMCX connectors over U.FL myself, no question. HOWEVER, I can regale you with the joys of trying to disconnect a long-installed MMCX connector while 80' up a tower. :( I for one would gladly pay a few bucks for a custom tool that would enable me to pop one of these beauties without damaging it as the need strikes.

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