isolated from ground. That part of the design problem seems non-trivial.
> the tuner input. It's just a matter of whether you think the lower
>
> Alan N1AL
>
>
> On Thu, 2011-12-08 at 18:59 -0500, Don Wilhelm wrote:
>> This is of interest to me, because in my first experiences with antenna
>> forums (or was it newsgroups at the time), I recall a lot of exchanges
>> with Tom W8JI on exactly the "balun at the tuner input and isolated
>> unbalanced tuner". I concur with Tom - it does not work -- both from a
>> theoretical basis, and also from Tom's measurements.
>>
>> This was "way back when" - as I recall my situation when all this was
>> going on, I was running Windows 95 and the year was between 1997 and 1998.
>>
>> In the timeframe of this discussion, Zack Lau (ARRL engineer) who had
>> first published the "balun at the tuner input" concept as a QRP tuner,
>> had retracted that design because it did not maintain balance, but Dean
>> Straw (ARRL engineer, editor, etc.) published his design of a high power
>> tuner using the same concepts, and that design can still be seen in the
>> ARRL publications.
>>
>> Apologies for the comments into the politics of the ARRL decisions on
>> what is to be published, but that is both a bit of the history as I know
>> it as well as my view of the technical side of this issue.
>>
>> If anyone can tell me how you can run a signal through a balun - and
>> have equal and opposite currents at its output, and then run it through
>> an unbalanced network with unequal elements in the two series legs and
>> still maintain equal and opposite currents and phase, and I will then
>> concede that an isolated unbalanced tuner with a balun at the input will
>> work, but until that is presented to me along with detailed engineering
>> level test data (not just "it works"), I will continue to believe that
>> using a balun on the input of an isolated unbalanced tuner is a "pipe
>> dream" that does not mesh with reality.
>>
>> 73,
>> Don W3FPR
>>
>> aOn 12/8/2011 6:28 PM, Eric Swartz - WA6HHQ, Elecraft wrote:
>>> Hi Ignacy,
>>>
>>> This is a common misconception. (One which I held until recently. :-) It
>>> turns out there is no advantage to placing the balun at the input of the
>>> L-Network tuner. Since one end of the balun is grounded by the input to
>>> the tuner, it is still presented with the same stresses under high SWR
>>> situations. Baluns at the input and output both drive balanced loads
>>> equally well.
>>>
>>> We've now put together a web page describing the impact of placing the
>>> balun at the input or at the output of a L-Network tuner. See:
>>>
>>>
http://www.elecraft.com/KAT500/input_versus_output_balun.htm>>>
>>> At the bottom of that page are several links providing detailed
>>> technical analysis of these configurations. The first two, by W8JI and
>>> W7EL are very clear discussions of this issue.
>>>
>>> 73, Eric WA6HHQ
>>>
>>> www.elecraft.com
>>>
>>>
>>> On 12/8/2011 3:17 PM, Ignacy wrote:
>>>> It seems to me that the story is more complex than it sounds.
>>>>
>>>> The input balun always works at low SWR and at 50 Ohm. It is very easy to
>>>> have such balun. A small balun would easily handle a KW without heating.
>>> ______________________________________________________________
>
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