Posted by
David A. Belsley on
May 13, 2005; 6:02pm
URL: http://elecraft.85.s1.nabble.com/Balanced-tuners-tp378283p378288.html
Vic: You are right. The URL for the "brief" version of W7EL's paper is
<
http://eznec.com/misc/ibalbrf.txt>
and a more detailed version is at
<
http://eznec.com/misc/ibalun.txt>.
It's not clear to me why one would want to hang on to a balun in a
balanced tuner. A simple L-C network on the input is very effective
(or a movable link). Someone just posted that their best bet was a
homebrewed transmatch, and I agree with this. A balanced homebrewed
transmatch is a simple project. To be sure, it can be made very
complex if one wants, but that is really unnecessary. I have used my
Italian homebrew with great success for decades. I call it my Italian
tuner because it looks like a plate of spaghetti, but boy does it work.
best wishes,
dave belsley, w1euy
On May 13, 2005, at 11:13 AM, Vic Rosenthal wrote:
> David Honey wrote:
>
>> A true balanced tuner has the balun at the input where, once the ATU
>> is propery adjusted, will always be at 1:1 and hence no reactive
>> elements.
>
> This is not correct. As you suggest, placing the balun at the input
> of an unbalanced tuner is an attempt to solve the problem posed by
> operating a balun in the output of the tuner, where the impedance is
> uncontrolled. However, W7EL (I can't find the reference just now) has
> shown that this method is actually no better than the balun in the
> output!
>
> A true balanced tuner does not have a balun at all. For example, the
> Johnson matchboxes make the unbalanced to balanced transition by using
> an unbalanced link coupled to a symmetrical parallel-tuned tank
> circuit that is connected to the feedline. There are several true
> balanced tuners available: MFJ makes one, and I've seen others. Just
> Google 'balanced tuner'.
>
> --
> 73,
> Vic, K2VCO
> Fresno CA
>
http://www.qsl.net/k2vco> _______________________________________________
> Elecraft mailing list
> Post to:
[hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
>
http://mailman.qth.net/mailman/listinfo/elecraft> Help:
http://mailman.qth.net/subscribers.htm> Elecraft web page:
http://www.elecraft.com>
_______________________________________________
Elecraft mailing list
Post to:
[hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft
Help:
http://mailman.qth.net/subscribers.htmElecraft web page:
http://www.elecraft.com