"Jeff Liebermann" wrote in message
...
On Sun, 12 May 2013 16:34:53 -0400, "Ralph Mowery"
wrote:

"Jeff Liebermann" wrote in message
. ..

Yes, I know. A clean workbench is a sign of a sick mind.
http://802.11junk.com/jeffl/pics/home/slides/chain-saw-repair.html
It's currently not quite as messy, but it's close.

Looks like you have an antenna harness for phasing 2 meter antennas.

I guess you mean the Wilkinson power divider/splitter in the lower
left. It's not for phasing antennas, but for combining the signals
from two receive only 1090MHz antennas for ADS-B reception. The lines
are 3/4 electrical wavelengths long RG-6a/u because I couldn't find
any small diameter 75 ohm coax. That was a prototype I just threw
together to see if I really needed the 100 ohm resistor for receive
only. With low gain antennas, it's not needed. For high gain, where
impedance matching is more important, it's needed.


I know about the Wilkinsson devider. Not sure if it is done now, but the
CBers would put two antennas on their cars and especially the big trucks.
Feed them with a T and 1/4 wavelengths of coax if I recall corectly.
Thought you were going to do that to the chain saw for 2 meters to help out
your handy talkey while sawing wood. As if you could hear it over the
noise.

I have not looked over the power devider in a long time. I was thinking the
100 ohm resistor was mainly to absorbe the unballanced power. If everything
was matched you could leave it out, but as you well know, nothing is perfect
in the RF world.

What are you using for a receiver for the ADS-B ? I have one of the dongles
that plugs into the usb of a computer on order. Should be here Monday. It
tunes from about 25 MHz to over 1 Ghz from the writeups. Off ebay here is
the item number.
310655269457

I don' t see how they can make and ship a device like that for only $ 11.00.