John Devoldere (ON4UN) wrote:
>> Your tuner probably has worse than a 16 dB input match
>> when tuned. In industry anything better than 15 dB return loss is
>> generally considered a 50 Ohm load!
>>
>NOT ON VHF / UHF !!!!
Say, John, did you have to yell (caps) in your entire post?
Ok, that aside, for precision weak signal ham work in the VHF/UHF range,
I'll agree that a 15 dB return loss isn't great. However, there have
been all sorts of commercial designs that I have done and have seen where
a 15 dB or greater return loss is deemed sufficient. And that has been
at 800 MHz and above. That's all I was saying.
When I worked in the University of Illinois Electromagnetics Laboratory,
we generally had a rule of thumb for impedance plots on a Smith Chart.
If you could put a quarter dollar over the center of the plot and have
your entire S11 plot covered by the quarter, it was a good match. I
forget what the return loss would be at the outer edge of the quarter and
don't have time to look it up now.
Anyhow, my point again is that you don't have to get completely to 50
Ohms in order to have a sufficient match.
73,
Jon
KE9NA
--------------------------------------------------------------------------
The Second Amendment is NOT about duck hunting!
Jon Ogden
jono@enteract.com
www.qsl.net/ke9na
"A life lived in fear is a life half lived."
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