Thread: 91XG or DB8e
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Old 11-Aug-2017, 5:28 PM   #17
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Join Date: Jan 2010
Posts: 2,932
I wonder what is inside and how much current it will pass?
There's a reference circuit design in this MiniCircuits app note that is pretty much similar to almost every two port splitter I've opened. Ignore the "external" references in the diagram, those are for the design engineer's use who is using the device for his design. In the collection of splitters I have on hand and have opened, I see one or more differences in capacitors as well as some splitters that don't' bother with the isolation network between the two outputs (two coils and resistor).

Add to the list of potential splitters that include direct pass-through of DC the basic Ideal cable/TV splitter that anyone can pick up from Home Depot for $4 (85-132).

The basic splitters that do not pass DC power simply have a low-value blocking capacitor in series with the output port. For "satellite" splitters, they simply put a diode in parallel with the blocking cap to allow power to pass from either output back to the input. The sat-rated splitters also appear to use higher quality transformers and much better layout and construction techniques so as to extend their bandwidth.

As far as maximum current carrying capability, it's hard to say. It appears the transformers through which power must pass are all wound with a wire somewhere around 28-32 gauge.

Several of the samples I have include DC pass on one port only. All of these simply have a coil connected directly from the input to one of the outputs and include the blocking cap on both output legs.

I believe you are proposing something like this?
Pretty much along those lines although I wouldn't specify use the RCA amps due to my experience with them (poor reliability) plus the need for a different power source in order to run two of them off one source. If you do decide use them, you shouldn't need the HLSJ as a high-pass filter for FM.
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