On 11/29/2010 09:25 AM, jimlux wrote:
> Rik van Riel wrote:
>> On 11/28/2010 10:56 PM, DJ7WW wrote:
>>> A tuner working into a 5:1 mismatch would not improve the antenna and
>>> feed
>>> line loss anyway.
>>> A tuner is the wrong approach to compensate a bad antenna design.
>>
>> A 5:1 mismatch can be entirely reasonable depending on the band,
>> the antenna, etc...
>>
>> For example on 160m and 80m it is common to have high impedances
>> at the band edges, because these bands are just so wide (as a
>> percentage of the center freq).
>>
>> However, a 5:1 mismatch at 2 MHz with 100' of LMR-400 coax only
>> results in an SWR loss of 0.4 dB.
>
> It's too early in the morning for me to run the numbers, but in a
> mismatch situation, the coax loss could be much higher:
Go to the URL below, then type in the numbers:
>> http://www.saarsham.net/coax.html
0.17 dB matched loss
0.26 dB SWR loss
0.43 dB total loss
That is 100' of LMR-400 at 2 MHz with a 5:1 SWR.
Just how much trouble should one go through to avoid that
0.26 dB SWR loss?
--
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