[HomeBrew] 50 ohm receive splitter

[To Possibilities]

[[Does anyone have info on building a 50 ohm receive splitter for 3 to 
30 mhz?
Like what core and how many turns and I believe 1 resistor.]

Loren

You can make a 50 ohm splitter by winding a bifilar winding on a ferrite 
core and adding a 100 ohm resistor.

Refer to figure 3 at the following web page.

http://www.minicircuits.com/pages/pdfs/tran14-2.pdf

This shows how to wind a bifilar winding. Basically, cut two equal 
lengths of magnetic wire (26 ga. would be fairly easy to work with) , 
anchor one end and put the other end in a hand drill and twist together.

If you use a FT-37-43 ferrite core with 15 bifilar turns the splitter 
would be good from 1.6Mhz to 30MHz. For 3Mhz and up 11 or 12 turns would 
be good.

The turns should be identified with an ohm meter (or by using two 
different colors of magnetic wire). If #1 is one end, #2 is the other  
(likewise for # 3 and #4).

Now connect #1 to #4, This will be your primary winding and referenced 
to ground, your 50 ohm input.

#2 referenced to ground and #3 referenced to ground provide your two 
output ports.

Note that you have an auto- transformer with a 2:1 turns ratio. 
Therefore the voltage at each of your output ports will be half of the 
input voltage and each output will be 3dB less then than the input.. The 
impedance transformation is the turns ratio squared, or 4:1. The 2 
outputs appear in series across the transformer (i.e.100 ohms) So in a 
50 ohm system, you will also need to connect a 100 ohm resistor between 
#2 and #3. The transformer now has 200 ohms across it and transforms 
back to the input port as 50 ohms (for maximum power transfer).

Ed, W1AAZ

Lots of books, parts and kits for sale at:

http://mysite.verizon.net/topossibilities/