Yes Steve, you are correct.
You have two windings (transmission lines) with the 4:1 Guanella.
Usually the bifilar windings are about 100 Ohms.
Their inputs are in parallel and their outputs are in series.
This gives us 50 Ohms on the input and 200 Ohms on the output.
But if we re-wire the outputs to also be in parallel, then the two 100 Ohm
transmissions lines in parallel give us 50 Ohms on both ends.
Unfortunately the reverse does not always work.
Most 1:1 Guanella baluns simply run a coax cable around a single toroid so
you don't have the two transmission lines to play with.
But, if you build your own 1:1 Balun using two 100 Ohm bifilar transmission
lines rather than coax, THEN you have the possibility to switch it to a 4:1
or 1:1.
Having a switchable balun is a big help when you are trying to cover the
entire HF spectrum with a single antenna and you only have a marginal
antenna tuner, like the built-in tuners in transceivers. This can come in
handy when traveling light on portable expeditions.
73
Rick, DJ0IP
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Steve Hunt
Sent: Thursday, October 31, 2013 10:57 PM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] 160 meters, ten ted 238 tuner, part two
Rick,
Doesn't that halve the CM impedance?
Steve G3TXQ
On 31/10/2013 21:45, Rick - DJ0IP / NJ0IP wrote:
> Andy,
>
> If you have a 4:1 Current Balun, then you can easily re-wire it as a
> 1:1 current balun. You just swap two connections inside. IN FACT...
> if you have a big heavy duty switch, you can even make it switchable
> between 1:1 and 4:1.
>
> 73
> Rick, DJ0IP
>
>
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