50-300Ohm balun
 

I have a car antenne with 50 Ohm coax that I want to
connect to an old radio
with a 300 Ohm balanced input so I need a balun and
impedance converter. Any
info about how to build one will be welcome. (Being
an amateur I don't want
to buy one.)
=================================

Dear Pieter, pleased to meet you.

The first thing to say is that the impedance of the
short length of coax line between antenna and receiver
has very little to do with the unbalanced-to-balanced
transformer between coax and receiver input. The coax
is just a short length of wire between antenna and
receiver with a relatively small capacitance between
the the wire and ground.

To design a transformer more information is needed. But
whatever it is it will be a very easy to make. All you
will need is a small ferrite ring and a length of thin
enamelled copper wire.

What range of frequencies would you like your receiver
to cover? Long-waves, medium-waves, short-waves or VHF
FM

What sort of antenna are you using? Is it a simple
vertical whip connected directly to the coax.?

Is anything connected betwen the antenna and coax? How
high is the whip. Is the height of the whip
adjustable.

Please provide more information and the number of turns
of wire on what size ring can then be decided.
----
Reg, G4FGQ

You probably got one laying around.
you know that thing betweence the vcr and tv or cable box and tv?
75^ to 300^ close enough

Not in Europe - we use all-coaxial systems for TV over here (and are
thankful for it).


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
Editor, 'The VHF/UHF DX Book'
http://www.ifwtech.co.uk/g3sek
======================================
Too bad, I have a hard time walking around the block without seeing
at least 1 of these laying around on the ground.
Sell at the store sometimes .69USD
Love your website Ian,bookmarked it a while back,good info.
73
KC8VIF
Greg Z
to thine own sound be true

greg z wrote:
You probably got one laying around.
you know that thing betweence the vcr and tv or cable box and tv?
75^ to 300^ close enough
73

Is the old radio an AM, FM, or both? I'm not sure the 75/300 TV
balun is rated for 1 MHz operation.
--
73, Cecil http://www.qsl.net/w5dxp



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