[TenTec] OCF antennas evolution

[Bob McGraw - K4TAX]

Then explain why a 4:1 balun is needed.  Heck I might learn something.

73
Bob K4tAX


----- Original Message ----- 
From: "Mike Bryce" <prosolar at sssnet.com>
To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Sent: Thursday, July 11, 2013 8:50 PM
Subject: Re: [TenTec] OCF antennas evolution


>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 at 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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