Re: Gamma-matching antenna tuner

hirosmb <hirosmb@...>
 

Allison-san,

Thanks a lot for your info.

I am checking those presented URLs and a bit surprised with a huge filter using PC case. :)

In my understanding, because uBitx uses DDS and so is not likely to produce lower harmonics such as by frequency multiplier, but higher harmonics may occur in most cases.

Also I am afraid that the fixed BPF or LPF (such as until 30MHz) may not suppress the second harmonics (14MHz) when emitting 7MHz CW, but hoping that the pi-match antenna tuner may work for this case.

// hiro, JJ1FXF



2018/07/31 0:07、ajparent1/KB1GMX <kb1gmx@...>のメール:

Hiro san,

A pi type tuner is generally in the same form as Low pass filters.  As such it can help with harmonics
but lower frequency spurious outputs it will be less helpful.

What you likely want is a transmitting band pass filter then an antenna matcher after that.
Two sites that may be more helpful.  

https://www.n1nc.org/Filters/

http://orarc.net/RF-Filters-2.pdf

Allison

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