Posted by
Hisashi T Fujinaka on
Apr 26, 2012; 4:16pm
URL: http://elecraft.85.s1.nabble.com/New-KAT500-pics-from-the-Visalia-DX-convention-tp7500313p7503419.html
Just a quick question:
> On 4/25/12 7:09 PM, Alan Bloom wrote:
> Since two N or UHF adapters were used, I assume the loss per connector
> is half the total. The vertical scale was .1 dB/division, so I estimated
> the insertion loss to the nearest .01 dB or so:
>
> --------- Type N -------- ---------- UHF ----------
> FREQ (MHz) TOTAL LOSS PER CONNECTOR TOTAL LOSS PER CONNECTOR
> 1.8 0 dB 0 dB 0 dB 0 dB
> 30 0 0 0 0
What are the measurements below this? I'm not sure I can work any
DX at those frequencies. I always tell my microwave experimenter buddies
that if I can walk there and talk to the guy, I'll do that and not worry
about my radio. :)
> 100 0 0 0 0
> 150 0 0 0.02 0.01
> 200 0 0 0.03 0.015
> 450 0 0 0.18 0.09
> 600 0 0 0.26 0.13
> 900 0 0 0.66 0.33
> 1000 0.05 0.025 0.8 0.4
> 1300 0.1 0.05 0.86 0.43
> 1600 0.05 0.025 0.5 0.25
> 2000 0.05 0.025 0.02 0.01
Oh, and for technical content: even though you get an impedance
mismatch, at the frequencies I care about the mismatch is so short that
you don't make it far around the Smith chart (easier than doing the
calculations). It doesn't really matter that a UHF connector isn't
exactly 50 ohms when it's << a wavelength, 1/10 the wavelength.
So if a UHF connector is about an inch, 10 times that is about 10
inches, or about what I think is a nanosecond is (about a foot) which is
10^9Hz or about a gigahertz.
So back-of-the-envelope, UHF connectors impedance mismatch only matters
around a gigahertz. This would horrify my engineering profs because
MIT back-of-the-envelope calculations would require Maxwell's equations.
--
Hisashi T Fujinaka -
[hidden email]
BSEE(6/86) + BSChem(3/95) + BAEnglish(8/95) + MSCS(8/03) + $2.50 = latte
______________________________________________________________
Elecraft mailing list
Home:
http://mailman.qth.net/mailman/listinfo/elecraftHelp:
http://mailman.qth.net/mmfaq.htmPost: mailto:
[hidden email]
This list hosted by:
http://www.qsl.netPlease help support this email list:
http://www.qsl.net/donate.html