# TC1-1-13MA+ RF Transformer

**URL:** <https://discourse.myriadrf.org/t/tc1-1-13ma-rf-transformer/1099>\
**Category:** Component Libraries\
**Created:** [11 April 2017 09:22 UTC](https://discourse.myriadrf.org/t/tc1-1-13ma-rf-transformer/1099 "2017-04-11T09:22:08Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![Ronald](https://avatars.discourse-cdn.com/v4/letter/r/ea666f/32.png) [@Ronald](https://discourse.myriadrf.org/u/Ronald)\
**Post date:** [11 April 2017 09:22 UTC](https://discourse.myriadrf.org/t/tc1-1-13ma-rf-transformer/1099/1 "2017-04-11T09:22:09Z")

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Could someone please let me know what transformers are actually on the board. If you compare the datasheets from Minicircuit with the LimeSDR schematics it doesn’t make sense:

TCM1-63AX+ Has a winding connecting the primary and secondary. How is that going to work? For sure there is no isolation.

TC1-1-13MA+ Part does not have a center-tap. How is that going to work?

Please explain. I’m doing my own LMS7002-based design and need to get this fixed ASAP.

Ronald

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**Author:** ![Kc7noa](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/kc7noa/32/144_2.png) [@Kc7noa](https://discourse.myriadrf.org/u/Kc7noa)\
**Post date:** [11 April 2017 16:53 UTC](https://discourse.myriadrf.org/t/tc1-1-13ma-rf-transformer/1099/2 "2017-04-11T16:53:06Z")

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Well the isolation is done more with the capacitor than transformer …

and when dealing with a 1:1 transformer as long as the input and output are not in series or parallel … it will work, but keeping primary separate from secondary always helps with ESD/loop isolation …

I didn’t look hard at the board placement of the 1.4V board …

Id say place the transformers as you see fit …

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**Author:** ![JMG](https://avatars.discourse-cdn.com/v4/letter/j/e68b1a/32.png) [@JMG](https://discourse.myriadrf.org/u/JMG)\
**Post date:** [11 April 2017 18:39 UTC](https://discourse.myriadrf.org/t/tc1-1-13ma-rf-transformer/1099/3 "2017-04-11T18:39:57Z")

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It is not a transformer. It is a balun!

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**Author:** ![Kc7noa](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/kc7noa/32/144_2.png) [@Kc7noa](https://discourse.myriadrf.org/u/Kc7noa)\
**Post date:** [12 April 2017 20:19 UTC](https://discourse.myriadrf.org/t/tc1-1-13ma-rf-transformer/1099/4 "2017-04-12T20:19:02Z")

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> [@JMG](#):
>
> It is not a transformer. It is a balun!

Wires around a form …

Balanced to unbalanced …

Same device used in different ways … some times doing both , impedance transformation AND balToUnBal …

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**Author:** ![Kryan92](https://avatars.discourse-cdn.com/v4/letter/k/e480ec/32.png) [@Kryan92](https://discourse.myriadrf.org/u/Kryan92)\
**Post date:** [13 April 2017 00:49 UTC](https://discourse.myriadrf.org/t/tc1-1-13ma-rf-transformer/1099/5 "2017-04-13T00:49:26Z")

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It’s a transformer with characterized RF performance and a specific turns ratio.

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**Author:** ![Kryan92](https://avatars.discourse-cdn.com/v4/letter/k/e480ec/32.png) [@Kryan92](https://discourse.myriadrf.org/u/Kryan92)\
**Post date:** [13 April 2017 00:54 UTC](https://discourse.myriadrf.org/t/tc1-1-13ma-rf-transformer/1099/6 "2017-04-13T00:54:00Z")

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You’re going to shoot yourself in the foot if you’re doing an RF design without any requisite RF knowledge. As good of an all-in-one the Lime Transceivers are, they’re still dealing with RF signals.

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**Author:** ![JMG](https://avatars.discourse-cdn.com/v4/letter/j/e68b1a/32.png) [@JMG](https://discourse.myriadrf.org/u/JMG)\
**Post date:** [13 April 2017 07:54 UTC](https://discourse.myriadrf.org/t/tc1-1-13ma-rf-transformer/1099/7 "2017-04-13T07:54:29Z")

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To be more specific:  
It is a balun. Acting as a “common mode choke” aka “current balun”.  
No impedance transformation.  
Below its cutoff frequency the output signal is not symmetrical any more.