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[TowerTalk] 75 ohm coax matching

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Subject: [TowerTalk] 75 ohm coax matching
From: (Chuck Dietz)
Date: Mon, 07 Jul 1997 21:59:02 -0500
Larry A. Crim wrote:
> On Mon, 7 Jul 1997 wrote:
> > A little known and used method of matching 50 ohm loads and sources to 75 
> > ohm
> > coax is the "series transformer". They are by their very nature single band
> > devices but there are applications as they allow the 75 ohm line to be any
> > desired length.

> Has anyone actually used this idea in practice?

I have used it and it works great even if you don't use an antenna
bridge to get the lengths exactly right.  I have used this for stacked
antennas to return the impedence to 50 ohms after combining the two
stacked beams in parallel (which yields 25 ohms).  The great thing about
it is that you can have an upper/lower/both beams switch and use the 50
ohm section of the transformer to connect to a second relay box which
switches the length of 75 ohm cable in/out accordind to when there is
one or two beams in the circuit.  It works great!

Anyone trying to stack two monoband beams who needs more info on this,
please e-mail me.

Chuck, KE5FI

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