What do you mean by a single core Tom? Do you mean that this type of
balun requires 2 cores stacked on top of one another? Or 2 cores making
up 2 actual transformers?
Could you please explain that?
Thanks!
73
Jim W7RY
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Tom Rauch
Sent: Wednesday, August 31, 2005 4:58 PM
To: Tod - ID
Cc: towertalk@contesting.com
Subject: Re: [TowerTalk] Needed: Balun and Unun text by W2FMI
I concur with Tom's evaluation -- the later editions are
better technically
-- I have both the original and later editions.>>
The edition I kept was third printing 2002 by CQ
Communications.
The only real snafu's I've found in that printing are with
the evaluation of a dipole and why it needs or doesn't need
a balun (the theory is incorrect and the test of a dipole
isn't a valid test) and some statements that a single core
can be used to make a 4:1 current balun using a pair of
transmission line mode transformers. MFJ actually built a
4:1 balun that way and the balance is very poor. As a matter
of fact it really doesn't act like a balun, let alone a
current balun.
The exception is a conventional primary-secondary mode
transformer. That type of system CAN be wound on a single
core in any ratio, since it is in effect just an isolation
transformer. True transmission line mode transformers like
Sevik describes, other than a 1:1 ratio, cannot be placed on
a single core without screwing up balance.
73 Tom
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with
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_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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