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Re: Topband: 10 to 1 Ferrite Balun

To: Herbert Schoenbohm <>, TopBand List <>
Subject: Re: Topband: 10 to 1 Ferrite Balun
From: "Richard (Rick) Karlquist" <>
Date: Tue, 19 Mar 2019 12:01:54 -0700
List-post: <>

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.

Rick N6RK
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