Sherrill, the 238 is basicly a L tunner. It can be reversed to match either
high impedance or low impedance. There is a extra coil to extend the range
that make a limited T tunner at higher frequencies. The T network in the
ARRL antenna tunner has a very narrow bandwidth especially at low frequencies.
The 238 far superior for unbalanced loads. To have the balan on the input
would compromise the unbalanced preformance, since the power would have to
got through the balan even when driving an unbalanced load. I use T-200-2
powered iron toroids for baluns. They will not saturate and waste power.
I do not use the balun built in the 238.
Best regards, Jim FitzSimons W7ANF
Sherrill WATKINS wrote:
>
> While I am a devoted fan of Ten Tec gear, I will not recommend their tuners
> as being the "best" design for use with open wire
> transmission lines. This is because it is my understanding that the design
> is a basic T type L C network. This is fine for
> unbalanced line but not balanced. The solution the factory uses is to place
> a balun in the output of the tuner. While this may
> work just fine into a perfect impediance match, it defeats the purpose of
> using open wire line. That is to obtain tremendous
> bandwith and very high efficiency by using a properly designed antenna tuner
> that has true balanced output. An example of this
> design is the old Johnson Matchbox and many examples of this type are shown
> in the ARRL Antenna Book and Handbook. It is common
> knowledge that high reflected power will cause an iron core balun to
> "saturate" and generate heat from the precious reflected power,
> thereby wasting power. A much better method for feeding open wire line is to
> place the ba!
> lun on the input side of the T type tuner. Why this simple solution never
> occured to the factory seems odd? However, I understand
> that there is one company that does make an antenna tuner with the balun on
> the input side, specifically for feeding open wire line.
> Seems like Ten Tec could do the same for very small, if any cost. -
> Sherrill W. k4own
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