View Single Post
  #2   Report Post  
Old January 29th 08, 12:22 AM posted to rec.radio.amateur.antenna
K7ITM K7ITM is offline
external usenet poster
 
First recorded activity by RadioBanter: Jul 2006
Posts: 644
Default 70cm reflectometer?

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