[R-390] UnBal for R-390A

[Flowertime01 at wmconnect.com]

Tisha,

One of the things you can do is move swap one of the balanced leads over to 
the unbalanced input on the inside of the antenna relay. 

Move P207to J105 and then ground P206. Put J207 to J105 if you want.

This just lets you use the C connector as an input. you still are routing the 
signals through the first stage of the RF filter sections.

The input is still in the 200 ohm balanced input range.

A 4 : 1 balun will get the input down to 50 - 75 ohms. The match is close 
enough. The input to the receiver is not really 200 Ohms. It varies over 
frequency and is mostly higher.

The TV 75 ohm to 300 ohm things work OK. some do not get down to the AM band. 

I use a short length of twin Ax coax from the receiver into a shielded box 4 
x 4 x 4.

Inside the box I have run several different balun's depending on what antenna 
I happen to have. I use a lot of end feed long wires with real high Z. so 
take the balanced and go 4:1 to get up to 1600 ohm. for the long wire.

I have also used a 360 PF var cap in the box to peak, trim, filter, The 
signal match.

The twin ax to remote box, with the shield grounded at the box and the box 
grounded, has really helped me to get a bunch of neighbor hood signals out of 
the mix going into the receiver. I also put my receiver into a cabinet and 
grounded the cabinet.

I was living in San Diego and LA for 20 years. You need all the edge you can 
get in the big cities.

Roger AI4NI
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