Instrument Enthusiasts,

Here's a few of the links to descriptions of instruments that provided
information cited in the global change discussion.

DOE Atmospheric Radiation Measurement (ARM) Program Instruments

http://www.arm.gov/instruments/

NASA Atmospheric Infrared Sounder (AIRS)

http://daac.gsfc.nasa.gov/AIRS/instruments.shtml

NASA Compact Reconnaissance Imaging Spectrometer for Mars

http://www.nasa.gov/mission_pages/MRO/multimedia/pia10137-caption121107.html

NASA Stratospheric Tracers of Atmospheric Transport (STRAT) instrument
list

http://code916.gsfc.nasa.gov/Public/Analysis/aircraft/strat/strat.html

NOAA Airborne Aerosol Lidar (Light Detection and Ranging)

http://www.etl.noaa.gov/technology/abael/

NOAA Calibrations of CO2 Reference Gases

http://www.esrl.noaa.gov/gmd/ccgg/refgases/manometer.html

NOAA Chemical Sciences Division WP-3D Instrumentation

http://www.esrl.noaa.gov/csd/ARCPAC/p3instruments.html

NOAA Ground-Based and Airborne Microwave Radiometers

All,

I'm seeing posts like the following every couple days on “Six Club.”

“A few minutes ago, worked KG4HOT/mobile in FM07 while I was mobile in
EM57. He was a solid 5-9. FYI, my set up a yeasu FT-857d, 100 watts,
into a whip antenna. Band was crowded with 1's, 2's 3's, and 4's.

“N9LAG Rob
“Grid EM-57”

Any idea why we're seeing sporadic-E activity so early in the cycle?

SixClub mailing list
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Hi,

I have been running many automated NEC2 runs to optimize a 5 band
quad. My criteria included bandwidth and all my runs to date have
been done assuming direct feed with 50 Ohm coax.

I'd like change the criteria and allow the feedpoint impedance to drop
below 50 Ohms now, with the expectation that I would use a gamma match
at the feedpoint. Using a gamma match at the feedpoint, for me, would
be more advantageous because this means the driven elements of the
inactive bands will truly be closed loops (eliminating the need to do
other things to achieve this, relays, specific lengths of coax, etc.).
I would place a choke at the gamma match feedpoint as well.

Since (2.5:1 SWR) bandwidth is still something that is important to
me, I need a way to calculate it. Would it be a mistake to take the
real impedance at the center design frequency, make this the line Zo
and then take the reactance at the center frequency as well and offset
the reactance at all frequencies this amount?