Topband: 10 to 1 Ferrite Balun

[Richard (Rick) Karlquist]

Correction ADT8-1T+ transformer

Rick N6RK

On 3/19/2019 12:01 PM, Richard (Rick) Karlquist wrote:
> 
> On 3/19/2019 8:47 AM, Herbert Schoenbohm wrote:
>> I am working on an RX antenna that requires about balanced 800 match 
>> to 75
>> ohm RG-6.  I have some type 43 and 73 ferrite binocular cores but since
>> this is just an experimental RX antenna I wanted to use an easier 
>> approach.
>> I have two commercial baluns that are unmarked but bridge out to a 75-ohm
>> to 200- ohm match.  What would be the problem if I connected them with 
>> the
>> first balun output feeding the 75-ohm input of the second one with the
>> 200-ohm output of the first one? Anyone ever tried this. Would this also
>> give me excellent ground loop decoupling between the RG-6 and the 
>> antenna?
> 
> What you have proposed (cascading transformers) would not work well.
> What I have done that does work is to connect two MiniCircuits
> ADT8-1+ transformers in series to form a 100 ohm to 800 ohm transformer. 
>   "Connect in series" means to connect the two primaries in series, and 
> connect the two secondaries in series.  This is different from cascading 
> transformers.
> 
> This is an amazing transformer, much better specs than similar models
> from MCL.  I dissected one of these in an attempt to reverse engineer
> it but was unsuccessful.  So you can't make your own with binocular
> cores.  At least not with the same performance.
> 
> 73
> Rick N6RK
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