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. Peter HA5RXZ

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.

Peter HA5RXZ