(Araucaria) Fwd: [CQ-Contest] Coax Stubs for SO2R

[Fernando Cordoba]

Bom dia pessoal,

Textos importantes sobre stubs e filtros.

73's

Fernando Cordoba | PY2LED | PX2B
São Caetano do Sul | SP | Brasil 
Alto da Serra Contest Station | GG66RJ
py2led em fuertesind.com.br



Início da mensagem encaminhada

> De: Jim Brown <k9yc em audiosystemsgroup.com>
> Data: 18 de julho de 2016 02:08:57 BRT
> Para: cq-contest em contesting.com
> Assunto: Re: [CQ-Contest] Coax Stubs for SO2R
> Responder A: k9yc em arrl.net
> 
>> On Sun,7/17/2016 11:08 AM, Rudy Bakalov via CQ-Contest wrote:
>> Just wondering, why use stubs at first place?
> 
> Properly done, they can kill second harmonics of the power amp. That's a big deal when you're operating SO2R CW on 80, 40, and 20.
> 
>> What's the advantage compared to LPF or BPFs?
> 
> Most of these filters are designed to run at the 100-200W level, so must be between the transceiver and the power amp, so they do NOTHING for power amp harmonics, which can be quite strong, depending on antenna spacing.
> 
> Here's an applications note I wrote for NCJ. http://k9yc.com/LocatingStubs.pdf
> 
> 4O3A makes bandpass filters rated for high power, and can be put on the output of a power amp. They're not cheap. :)  5B4AGN measured some of them and sent me the plots. They're part of this report. They look very good.
> 
> http://k9yc.com/BandpassFilterSurvey.pdf
> 
> http://www.4o3a.com/index.php/products/high-power-filters/
> 
> 73, Jim K9YC
> 
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