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Old January 29th 08, 04:55 PM posted to rec.radio.amateur.antenna
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Default 70cm reflectometer?



K7ITM wrote:
On Jan 28, 1:52 pm, "Suzy" not@valid wrote:
Can anyone point me to a website where a home built 70 cm reflectometer or
70 cm field strength meter can be built -- not using surface mount
components. Thanks.


Are you willing to use a printed circuit board? If so, a directional
coupler is pretty easy to make, microstrip style. You can even use a
knife to score the copper and then peel away the unwanted copper.
It's common to have one through-line and two coupled lines, one for
"forward" and one for "reverse" measurements. You terminate each
coupled line with Z0 (50 ohms, commonly) at one end and put a diode
rectifier (or other power measuring device) at the other end.
Although it's probably easiest to get a pretty good 50 ohm termination
at 450MHz using surface mount parts, you can do OK with a couple 1/4
watt metal-film axial resistors. If you used 1206 size surface mount
resistors, you should be able to solder them down with a decent
standard iron -- they aren't all that small.

If you really can't find any construction articles on making one,
maybe I could put something together and post it somewhere. They're
far easier to make than many people seem to think.

Cheers,
Tom


Don't let the surface mount parts intimidate you. Its not that
difficult especially when you are doing just a few componets. I must
admit that I had a heck of a headache after building a little
microphone preamp. I glue the part I am going to install to a
toothpick to give me something to hold it with.

Jimmie
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