A balun on the output side of an unbalanced tuner is a compromise that allows
a tuner to be built cheaper and work with both balanced and unbalanced
antennas.
A balun will always have some loss, and more reactive loads will tend to
increase the loss. The loss shows up as heat, but the amount of heat noticed
is also related to the size of the balun. A physically larger balun will
distribute the heat across it's larger surface area and therefore will appear
to be cooler than a smaller balun dissipating the same amount of heat. So a
large balun may indeed be just as lossy as a smaller balun, but still feel
cooler.
So, be sure to compare apples to apples. The only real way to test the
efficiency of a balun in to measure power in and out, or measure the
temperature change in the air in a controlled chamber. The efficiency will
also vary with the resistance and reactance of the load.
73,
Darrell
VA7TO
On Thursday 21 May 2009 07:38, Walter Hopper wrote:
> Hi Chris..
> In this particular case, I suggest that you would be better served in not
> comparing "brands"... but designs. Any tuner which matches balanced
> feedlines with a balun, generates heat in the balun. As W5TJ once told me:
> " the receiving station can not hear heat". So, the problem is solved by
> using a balun which employs two coordinated matching coils. I won't
> mention brands, but I am using one with 600ohm feedline, and the heat
> problem is eliminated. Do a little investigating.
> 73
> Walt K5VV
>
> On Thu, May 21, 2009 at 9:17 AM, Chris Hinson
<chinson1@mindspring.com>wrote:
> > Sorry I mean the 238B just a error
> > 73s Chris K4osk
> >
> > > [Original Message]
> > > From: JT Croteau <jt.n1ese@gmail.com>
> > > To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
> > > Date: 5/21/2009 10:11:09 AM
> > > Subject: Re: [TenTec] Re(Ten TEC) Palstar Tuner
> > >
> > > On Thu, May 21, 2009 at 10:04 AM, Chris Hinson
> > > <chinson1@mindspring.com>
> >
> > wrote:
> > > > Out of all three The Ten-Tec 138B performs the best. The TT 138B
> >
> > matches my
> >
> > > > antennas the best giving me the lowest SWR. on 160-10 meters
> > >
> > > Lowest SWR doesn't always equate to the best match. Also, do you mean
> > > to say 238B? There's no such thing as a 138B.
> > >
> > > --
> > > JT Croteau, N1ESE
> > > _______________________________________________
> > > TenTec mailing list
> > > TenTec@contesting.com
> > > http://lists.contesting.com/mailman/listinfo/tentec
> >
> > _______________________________________________
> > TenTec mailing list
> > TenTec@contesting.com
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>
> _______________________________________________
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--
Darrell Bellerive
Amateur Radio Stations VA7TO and VE7CLA
Grand Forks, British Columbia, Canada
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