That's right almost like a dead short to RF in many cases I expect.
Best regards - Brian Carling
AF4K Crystals Co.
117 Sterling Pine St.
Sanford, FL 32773
Tel: +USA 321-262-5471
> On Sep 15, 2014, at 10:11 AM, "Rick - DJ0IP / NJ0IP" <Rick@DJ0IP.de> wrote:
>
> In addition, if the antenna (i.e. dipole) has a balun using a ferrite toroid
> and we try to match the antenna on a band for which it was not designed,
> with help of a matchbox, then there is additional loss in the balun, which
> often can be significant.
>
> 73 - Rick, DJ0IP
> (Nr. Frankfurt am Main)
>
>
> -----Original Message-----
> From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Bob McGraw
> - K4TAX
> Sent: Monday, September 15, 2014 4:01 PM
> To: k9yc@arrl.net; Discussion of Ten-Tec Equipment
> Subject: Re: [TenTec] SWR is a DUMB Indicator of Antenna Performance
>
> It seems that here we fall largely to the victim of verbal semantics.
> Almost every radio I've owned, as well as the related printed manual, gives
> the indication there is a place to connect "the antenna". In fact, we don't
> actually connect the antenna but more correctly we connect the "feed line"
> or "transmission line" to the equipment and it is that feed line or
> transmission line that is actually connected to the antenna.
>
> In general the generic description we use, the antenna, has to do with the
> radiating part of our station, via various interconnect means, being
> described as "the antenna" and thus any tuning, more correctly matching, is
> then stated as "tuning the antenna".
>
> Yes, feed line loss due to SWR is a concern in many instances. Many
> feedline materials or choices have very low loss when operating at a matched
> condition. However we find the loss goes up rather dramatically when the
> feedline is operated at other than its design impedance. One needs to
> consult the published charts and tables to determine the matched loss for a
> given type of feedline and then an additional table to add the loss value
> when the feedline is operated with some value of SWR other than a 1:1
> condition or matched condition.
>
> What is frequently overlooked, we take a given feedline having a loss of 1
> dB per hundred feet in a matched condition and use that feedline in a
> condition where the SWR on the line is 10:1. We then find the total loss is
> 1.0 dB plus the added loss due to SWR of 2.5 dB for a total loss of 3.5 dB.
>
>
> 73
> Bob, K4TAX
>
>
> ----- Original Message -----
> From: "Jim Brown" <k9yc@audiosystemsgroup.com>
> To: <tentec@contesting.com>
> Sent: Monday, September 15, 2014 1:53 AM
> Subject: [TenTec] SWR is a DUMB Indicator of Antenna Performance
>
>
>>
>>> My Ten-Tec 238 tune my 80 double ext.zepp on all bands 160-10 with a 4-1
>>> balun 182 ft of 400 ladder line then the 4-1 with 20ft of coax.
>>
>> No, it doesn't "tune" your 80 double ext.zepp, it creates a match between
>> the transmitter and the FEEDLINE that allows the transmitter to dump power
>
>> into the FEEDLINE. How much of that power gets to the antenna depends on
>> the mismatch between the feedline and the antenna. It's pretty common to
>> lose 10 dB between the transmitter and an "all band" dipole. 10 dB is 90%
>> of the transmitter power.
>>
>> I can make my 80M dipole look like 1:1 on 30M to my 200W amplifier, but
>> mismatch loss is determined by the match between the ANTENNA and the
>> FEEDLINE, and I would be burning 180 of those 200W in the feedline.
>>
>> Bottom line -- SWR is DUMB, STUPID, and USELESS as a measure of antenna
>> performance. I can LOAD a lightbulb, but it's a lousy antenna.
>>
>> 73, Jim K9YC
>> _______________________________________________
>> TenTec mailing list
>> TenTec@contesting.com
>> http://lists.contesting.com/mailman/listinfo/tentec
>
>
>
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