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New Member

Connecting a 100 Base FX transceiver to single mode fiber

I'm looking to connect to an ISP circuit. The fiber run is single mode and they have a 100 Base FX transceiver on their end.

I've looked up the specifications on that transceiver and it say's it should only be run on SMF. 

Anyone had any success with this?

 

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Accepted Solutions
Hall of Fame Super Silver

You're welcome.For a VERY

You're welcome.

For a VERY short run your MIGHT be able to get a SM transceiver to work over MM fiber.

The coherent light ("single mode") from the laser that launches into much larger core of the multimode fiber (usually 50 or 62.5 microns vs 9 micron for SM and having different propagation and dispersion characteristics) may "punch through" over short distances.

I wouldn't do it in any production environment though as it would likely be unstable in the long term (and is definitely not how the equipment is designed to work). 

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Hall of Fame Super Silver

The 100BASE-FX is designed

The 100BASE-FX is designed for and only works with multimode fiber. This is noted in the product data sheet.

The singlemode variants of the product line are listed on the same data sheet.

Whatever variation is being used should match at both ends and use the proper fiber (MM or SM).

New Member

thank you for your response

thank you for your response Marvin.

I'm just wondering if anyone has actually tried this. The ISP i'm working with claims that it works on both, though I highly doubt it.

Hall of Fame Super Silver

You're welcome.For a VERY

You're welcome.

For a VERY short run your MIGHT be able to get a SM transceiver to work over MM fiber.

The coherent light ("single mode") from the laser that launches into much larger core of the multimode fiber (usually 50 or 62.5 microns vs 9 micron for SM and having different propagation and dispersion characteristics) may "punch through" over short distances.

I wouldn't do it in any production environment though as it would likely be unstable in the long term (and is definitely not how the equipment is designed to work). 

New Member

Understood.. thanks again.

Understood.. thanks again.

New Member

Hello George,

Hello George,

I know you posted this question two years ago but I have a provider now that's doing the same thing:  They're using a 100Base-FX SFP over singlemode fiber.  Like you, we're thinking this shouldn't work.  

Did you try it?  And did it work?

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