75 or 50 ohm system

13/10/2021

 

Some test's.

I made a new RX9 only for testing.

Because it is a 75 ohm system on the RX port I had to transform it to 50 ohm external to fit it to the preamp (50ohm).

On the T1 transformer they are (manual YCCC) saying that you have to wind a 10turn transformer tapped at 5 to get the impedance that is coming from T2 18.75 Ohm transformed up to 75 ohm.

As you see below I am very close to the 75 ohm as the manuals says. The little deviation is because I am using the wrong resistors.

 

Because I am always trying to make it easier I adjusted T1 to a different winding than that is listed on the manual of YCCC.

I am using in this test 8 turns tapped at 5. 

As you see below I am getting very close to my needed 50 ohm for my preamp.

Also I don't use 75ohm coaxial Kable to my shack but 50 Ohm.

Its not my invention not at all but never thought about it to do it this way.

I learned it from the video of Steve VE6WZ on you tube with his design of the 9 RX board. 

It's working so later on I will adjust the old 9RX  to this system.

With this I can delete the old external transformation I made.