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Re: [Amps] how to wind an HF broadband 10:1 transformer

To: "'AMPS'" <>
Subject: Re: [Amps] how to wind an HF broadband 10:1 transformer
From: "Peter Voelpel" <>
Date: Sun, 2 Mar 2008 23:51:06 +0100
List-post: <">>
Manfred, total wire lenghts must have been 6-7m.
I fully agree to all your comments.

Powered iron core baluns are only suitable for tuned circuits, not for
wideband use.
A good example is the 1:4 balun behind a LC tuner to drive an open wire
feeder for multiband use, there ferrit cores will overheat quickly


-----Original Message-----
From: [] On
Behalf Of Manfred Mornhinweg


> I did that when I got my copy of V.O.Stokes book many years ago,
> where I found his wideband transformer concept. Using the largest
> ferrit toroids I could get, they were similar to Amidon #61, I
> sandwiched them between 5mm thick aluminum plates 20x10cm for 
> cooling, used 2x12 toroids and wound a 50:600 transformer with 3mm
> teflon covered wire to feed my terminated V-Beam from 160-10m. That
> worked perfectly well with all the power my modified L4B (3.5KV)
> could deliver.

The fact that you needed heat sinks makes me think that you ran those 
ferrites at pretty high flux density. That was probably necessary to get 
an acceptable wire length. How much wire did you have to wind on these 

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