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2.4 GHZ Antenna Bridge



Good evening to all,

I'd like to compare notes with anyone who has built the antenna bridge
that appeared in the September/October issue of the AMSAT Journal.  I
completed mu unit last week using my own PCB layout and I may have shot
myself in the foot.  I had a hard time keeping the oscillator going when
the meter circuit was terminated with a current meter.   For some reason
the circuit did not like some impeadances and he VCO would stop
oscillating.  Removing the current meter and reseting the power would
cause the oscillator to start again and I could measure voltage out ot
the meter jack but the bridge doesn't work that way.  I finally
discovered this afternoon that if I put my finger on the trace between
the output of the oscillator and the input to the splitter the oscillator
would run.  I tried a 5 pf capacitor to ground but that didn't work.  I
finally decided to widen the track which was a double "L" .05 inch wide
and about 1/2 inch long total.  I used some 1/8 inch copper strips made
for PCB repair and made the connection about 1/4 inch wide and the
problem went away.  Now it really works great.  You can match a helix in
nothing flat!

I used a 1/4 inch wide piece of flashing copper for the matching section.
 I did  not attempt to shape around the PVC boom I just used it straight.
 I also discovered that if I extended the matching section to about 1 5/8
inches the match was very broad.  I haven't found out if that is really
good or not.  I ran into some problems trying to match the grounded feed
unit and had to quit before I figured out the problems.

Has anyone built and used the bridge yet and if so what kind of results
have you gotten?

Thanks and 73's de Jess - W4MVB
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