Topband: question about RX splitter

[ZR]

By seperating the primary and secondary windings and using a hi mu ferrite 
such as the BLN73-202 the capacitance is minimized and common mode isolation 
is in excess of 35dB in the transformers measured here.

The resistor used for the splitter core is not 25 Ohms but rather 100 for a 
50 Ohm output. The input IMPEDANCE to that core is 25 Ohms.

Carl
KM1H


----- Original Message ----- 
From: "shristov" <shristov at ptt.rs>
To: <topband at contesting.com>
Sent: Monday, October 17, 2011 11:25 PM
Subject: Re: Topband: question about RX splitter


> VE2TZT wrote:
>
>> Additionally the primary of the splitter transformer is symmetric and 
>> isolated from the
>> secondary so, it seems that this splitter can at the same time provide 
>> common
>> mode isolation.
>
> Capacitance from primary to secondary will degrade common mode isolation
> on higher frequencies. Depending on your needs, it may still be 
> sufficient.
>
> The splitting and matching function is fine.
> The nominal value of the resistor is 25 Ohm.
> For 75 Ohm to 2 x 50 Ohm transformation
> the turns ratio should be (1 + 1) : 1.732.
>
>
> 73,
>
> Sinisa YT1NT, VE3EA
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