Right. I was answering your question, "Why not move the balun 200 feet away,
right up to the feed point?" At high SWR coax is lossy compared to OWL.
I believe an 80 meter dipole used on 40 has an impedance of something like 2400
+ j1700 for an SWR of about 75:1.
The 4:1 vs 1:1 balun question I'll leave to others.
Jon
On Jul 11, 2013, at 6:50 PM, Mike Bryce wrote:
> I quite aware that open line is generally considered lost less feed line.
>
> What threw me was the use of a 1:1 balun instead of a 4:1.
>
> That's the head scratcher.
>
> Mike wb8vge
>
> Sent from my iPhone
>
> On Jul 11, 2013, at 9:32 PM, k6jek <k6jek@comcast.net> wrote:
>
>> Mike,
>>
>> You're matching the antenna system, the antenna and the feed line. You just
>> can't separate the two. When the antenna impedance at a particular frequency
>> is different from the feed line characteristic impedance, the impedance on
>> the line is different every place on the line. You're matching whatever it
>> happens to be at the shack end of the feed line.
>>
>> Losses are the reason to put the balun near the station instead of near the
>> antenna. Open wire line has much lower losses than coax under conditions of
>> very high SWR. That's the reason we put up with the stuff which is a royal
>> pain in the arse, just so we can have a ridiculous SWR and not care about
>> it. And very high SWR is exactly what we have at almost all frequencies when
>> using a doublet as a multi-band antenna. The only reason we can get away
>> with such a thing is the low loss of open wire line. So you want to run that
>> stuff as far as you can before switching to coax. As long as you can is
>> ideally right into a balanced tuner, no balun at all.
>>
>> Jon
>>
>>
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