[Antennas] Johnson Tuners

Mon, 09 Jun 2003 19:52:31 -0700

This has proven not to be the case. Moving the balun to the input side of a=
=20
"floating" unbalanced tuner does not help the situation. Roy Lewallen has a=
=20
very good paper on the subject at ftp://eznec.com/pub/ibalbrf.txt

73
Danny, K6MHE

At 03:28 PM 6/9/2003 -0700, you wrote:
>
>    One variation in the tuner design is to use the balun on the input to=
=20
> the tuner, and then use a conventional unbalanced tuner modified to have=
=20
> floating inputs, and outputs. The balun sees no reactance when the tuner=
=20
> is matching the load, and this works well 160 -80 - 40 meters. Above that=
=20
> the circuit is not well balanced. I have used this arrangement for a long=
=20
> time with excellent results.
>
>Jim Candela
>WD5JKO
>
>
>Brian Carling <[email protected]> wrote:On 9 Jun 2003 at 0:25, Les=20
>Severson wrote:
>
> > With all the renewed interest in balanced fed all band dipoles I am
> > wondering why some manufacturer hasn't resurrected the link coupled,
> > Johnson design for a tuner. It sure beats cranking a rotary inductor
> > and a 4:1 balun for feeding a balanced line. Just look at what Johnson
> > tuners are going for on Ebay.. hi
> >
> > 73 to all, Les, W=D8OJH
>
>Probably because they are sometimes not as efficient. Link coupling in=
 final
>amplifiers can tend to be inefficient unless you get all the values right=
=20
>on each
>band. I had an Eldico transmitter with an 807 final and link-coupled out=20
>put. I never
>could get more than a few watts out of it. I changed the tank to a pi=20
>network, and
>immediately the output soared to over 30 watts.
>
>I can't say what those 4:1 baluns will do to the efficiency, but as you=20
>say, they
>have to be a weak link in the chain for a matching network too.
>
>
>
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