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Old July 24th 07, 12:12 AM posted to rec.radio.amateur.antenna
amdx amdx is offline
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First recorded activity by RadioBanter: Jul 2006
Posts: 349
Default Malfunctioning homebrew field strength meter


"Jerry Martes" wrote in message
news:Ih5pi.1716$9A6.1649@trnddc01...

"amdx" wrote in message
...
I built the circuit from the page below.

http://www.atvinderby.co.uk/2.4Ghz_SWR_Meter.htm

The I get 0v out when held near my wireless router, if
I put it near the microwave oven, the high input impedance
meter bounces up and down between 7mv and 80mv and
everything in between.
I used a 1N416E diode and a 1500pf filter capacitor. The
tuning cap doesn't have any affect.
Should this circuit work? If so what could I be doing wrong?

Mike


Hi Mike

That device looks so interesting to me that I will build one.
Have you thought about the reason for using the Quad? It seems that
complexity of the Quad+Reflector with the tuning capacitor might be used
for some reason other than gain. A dipole over a piece of copper would
be about the same "gain".
And, since the output of this device never needs to connect to a coax,
why do you suppose the *right angle* BNC is used?
I'll learn something from this project.

Jerry

I skipped the BNC connector altogether, soldered directly to the banana
plug connector.
I thought the Quad+Reflector was just for more gain and he says it is
horiz and vert polarized.
I have got a more stable output now, I tried it on my older microwave
(1988 model) and I got a more stable signal of as high as .8V, yea I had
to switch from the 200mv scale to the 2V scale. I decided to put a glass
of water in the microwave, then I could only get about 350mv. BTW the
measurements were taken on the outside of the oven at the door :-)
I need to go back to my tuning capacitor, I just grabbed a tiny air
variable from a
scrap pcb thinking it would be big enough, I'm questioning that decision
now.
Mike