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Re: www.amsat.org/amsat-new/echo/ModeJ.php



Keith N6ORS said...

>>www.amsat.org/amsat-new/echo/ModeJ.php
>
> That page, in particular lacks accuracy. Don't ask where those numbers
> come from...
Snip!

Hey Keith,

   They come from inexperience and no actual testing, since from around 1977
harmonic suppression on a vhf/uhf transmitter needs to be > or = to 60db,
1.2ghz needs to be > or = to 50db . so there is no way a properly working 2m
radio is putting out 1.56 watts on 432. Besides if you put 1.5 watts into
the front end of a gasfet preamp you can kiss it good bye...

quoting from the article..
"I used a small 50 ohm load of the type typically used to terminate the old
coaxial style local area networks, one I had lying around in my junk box. I
have no idea of the power handling capacity of the load, but since this was
receive only it seemed reasonable."

10-base-T  loads were usually a 1/4 watt or maybe a 1/2 watt, if
you really were putting 1.5watts into them they wouldn't last long
before they smoked,since the load doesn't smoke this should be a clue,and
the last statement makes no sense, receive only? how would that even apply?
isn't 1.5 watts 1.5 watts no matter what? If you really think you had 1.5 
watts
flowing around you could easily put a watt meter in circuit and see it and
check your theory.

The idea is sound, and it has been proven to work but the math in the
article is painfully wrong.

There really should be some sort of peer review before things gets posted as
gospel on the Amsat website.

73
wa6fwf
Kevin
#19623
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