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Subject: Wind Your Own RF Matching/Isolation Transformer
Date: Thu, 30 Apr 2015 11:00:00 -0700
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Wind Your Own RF Matching/Isolation Transformer =20
Wind Your Own RF Matching/Isolation Transformer
The simple DIY project for a broadband loop =
antenna =20
=A9 2013 Bruce A. Conti DIY =
- do it=20
yourself .DIY Option #1: The Mini-Circuits =
Shortcut Option=20
number one : Order an RF transformer from Mini-Circuits (or an eBay =
seller),=20
then complete the assembly by installing the Mini-Circuits trasformer in =
a=20
plastic chassis with appropriate antenna and lead-in connectors. This is =
the=20
easiest of the two DIY projects. However the Mini-Circuits transformers =
are so=20
tiny that they can be blown up by static electricity or a nearby =
lightning=20
strike. Although I've had relatively good experience with Mini-Circuits=20
transformers, even I've lost a few over the years. However, if the =
antenna is in=20
a location where the risk of lightning is low, then you could probably =
get away=20
with the Mini-Circuits DIY shortcut. The Mini-Circuits transformer comes =
in a=20
6-pin DIP (X65 package) like an integrated circuit. If the transformer =
is=20
mounted on a DIP socket, then at least it can be easily replaced if =
damaged.=20
When placing a Mini-Circuits order, it's a good idea to buy a couple =
extras just=20
in case.http://www.minicircuits.com/ DIY Option #2: Wind Your Own Option number two : Winding =
your own=20
RF matching/isolation transformers for broadband loop antennas is super =
easy,=20
especially if a binocular ferrite core is used. Wire is threaded through =
one=20
hole and then back through the other hole of the binocular core to =
complete one=20
turn of a transformer winding. The number of turns is determined by the =
square=20
root of the impedance ratio. For a 16-to-1 (16:1) impedance ratio, the =
actual=20
transformer winding ratio is 4:1. (The square root of 16 is 4.) In other =
words,=20
for for every four high impedance turns/windings, you'll need one low =
impedance=20
turn/winding. 20 turns for the high impedance and 5 turns for the low =
impedance=20
works well and maintains the desired 4:1 ratio. First wind 20 turns for =
the high=20
impedance on the ferrite core (photo below - left), then 5 turns for the =
low=20
impedance. Mark the high imedance end (photo below - right) so you don't =
forget=20
which is which during final assembly.Newark Electronics online =
catalog)Binocular=20
ferrite core with high impedance windings (left), and the completed =
transformer=20
with a dot marking the high impedance end (right). Final=20
Assembly The=20
completed assembly in a plastic chassis with binding posts and coax =
connector=20
(left), and a completed assembly using a food storage container for a =
chassis=20
(right). =A1BAMLog! =
home. =20