Electronics > RF, Microwave, Ham Radio

RF transformer confused schematic

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kendalll:
I'm confused by the schematic symbol for this RF transformer drawn as a choke. But if you look at the pin names, and the location of the dots, it looks like it's actually a 'standard' configuration transformer. Anyone know why this is? I posted in the RF section figuring maybe you guys might have run into this before.

Does anyone know why it's shown this way in the schematic for the ETC1-1-13? http://cdn.macom.com/datasheets/ETC1-1-13.pdf

rfeecs:
It's a transmission line transformer balun they are spec'ing like a power splitter.  Pin 1 is the input.  Pins 3 and 5 are the outputs.

Refer to figure 3a:
https://www.minicircuits.com/pages/BalunApplicationNote.htm

G0HZU:
Google for 1:1 "current balun"   :)

German_EE:
The schematic is incorrect anyway because a dot is normally used to indicate the start of a winding. One coil has two starts and the other coil never starts at all.

rfeecs:
In this case, the dot indicates the polarity.  They are calling pins 1 and 2 the primary and pins 3 and 5 the secondary.  Secondary dot pin 5 is in phase with primary dot pin 1.  Pin 3 is 180 degrees out of phase.

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