EMRFD Message Archive 7112
Message Date From Subject 7112 2011-12-26 12:21:07 ha5rxz Regarding The Problem Of Impedance Happy Christmas everyone!
You may remember the problem I had with dual low-pass filters and a pair of balanced fifty ohm ports. Well, with the girlfriend safely planted in front of the TV watching the DVD I bought her for Christmas I was able to retire to the shack and work this out.
50 ohm VNA > 1:1 balun > 2 x Low-Pass Filters > 50 ohm resistor
With the two filter grounds tied together and the dummy load floating I tried this with 25 ohm, 50 ohm and 100 ohm low-pass filters and got an almost 1:1 match with the two 25 ohm networks. By halving the values of the capacitors I was then able to join the two filters together to make a balanced 50 ohm filter.
Sorted. Back to the mince pies.