I have secured the special call sign W7O (WHISKEY SEVEN OSCAR)
for use in commemorating the 40th anniversary of the launch of
OSCAR 7 on 15 November 1974. I plan on having this call on the
air between 15 and 24 November 2014, working satellites and
possibly other bands. I will work satellite passes from Arizona,
including AO-7 passes, and hope to recruit a small group of
operators who can work other passes that cover eastern North
America along with other places I can't work from here (Europe,
north Africa, South America). I may also try to get some
operators working HF with this call.
I will handle the QSL requests for W7O during this period. I
am thinking of incorporating the original QSL card design
AMSAT used to confirm AO-7 reception reports from the 1970s
in the W7O card. (Does anyone have a good scan of both sides
of that 1970s QSL card? Not the 30th anniversary AO-7 card -
I have those, and there is a copyright on that design I do not
wish to violate.) The QSL cards will be printed after the
W7O activity wraps up. I will also upload W7O QSOs to ARRL's
Logbook of the World system.
Please contact me directly if you have any questions related
to this operation, or if you are willing to operate on satellites
and/or HF as W7O during this 10-day period.
Thanks in advance, and 73!
>From Via Satellite:
NASA Completes First Review of Wallops Launch Site Damage
By Caleb Henry | October 30, 2014 | Satellite TODAY News Feed
[Via Satellite 10-30-2014] NASA's Wallops Incident Response Team has
concluded its preliminary assessment of the launch pad at Wallops Island,
Va. following Orbital Sciences' Oct. 28 Antares launch vehicle explosion.
Initial findings show the damage was largely contained to the southern
third of the island. The team discovered imploded doors and shattered
windows at many nearby support buildings. The closest buildings and a
sounding rocket launcher adjacent to the pad were the most affected
infrastructure. The transporter erector launcher and lightning suppression
rods at Pad 0A were also damaged.
Several environmental tests are currently underway. Air samples from three
different sites detected no hazardous substances, and the U.S. Coast Guard
and Virginia Marine Resources Commission have not observed obvious signs of
water pollution, such as oil sheens. More testing of air, water, and soil
samples are planned for comparative analysis.
The response team will take several weeks to continue evaluating the extent
and influence of the damage. Local authorities such as the Virginia
Department of Environmental Quality, the Virginia Department of Emergency
Management and the Virginia Marine Police are also involved. NASA cautions
anyone who discovers debris from the explosion to keep distance and report
it to the Incident Response Team at 757-824-1295.
We try to preserve for posterity a list of those who observed or gave presentation to the Board.
While not required, if you would like to be included, let me know. We already have the various
officers and members. Here is our current list:
Bill Tynan, W3XO
Clayton Coleman, W5PFG
Dan Schultz, N8FGV
Dave Taylor, W8AAS
Hector L. Martinez, CO6CBF/KF5XYV
Jennifer Rojowski, N8GZL
Jim Hain, W2IMY
Joe Fitzgerald, KM1P
Keith Pugh, W5IU
Jan King, W3GEY
Nick Pugh, K5QXJ
Pat Kilroy, N8PK
Patrick Stoddard, WD9EWK
Phil Karn, KA9Q
Ray Hoad, WA5QGD
I keep coming up with the number of turns of a torque coil vanishing with
respect to torque (for a given wire size).
Given that Torque = A x B x I x n where A is area, B is field, I is current
and n is number of turns.
But I is inversely proportional to the length of wire (resistance). I = V/R
but R is proportional to n.
Hence the number of turns. So I is proportional to V/n.
But V is fixed in the cubesat, (5v) area is fixed (where we can put the
coil) and so plugging in,
T = A x B x V/n x n and the n’s cancel.
So I can get the same torque with –any- number of turns for a given size
What changes with turns, of course, is the current. So to save spacecraft
power, the more turns, the less current, and thus, the least power for the
We ended up with 600 turns of #34 wire to keep the current at 25 mA so we
can drive it directly from a CPU pin.
I wonder where’s the limit? Infinitie number of turns… Zero current? I
guess you run out of space.
AH HA! Yes, that was it. We started with #30 wire but it took so many
turns to get to below the 25 mA, that there wasn’t room for the coil. So
we went to smaller wire and ended up with the #34 to give us a ¼” thick
coil with 600 turns to give 25 mA.
But I just always found it interesting that once you have chosen the wire
size, the number of turns is only determined by the current you want. The
Torque is constant.
I am no rocket scientist, but wouldn't the earths magnetic fields tend
to bias those diodes on as the satellite cuts through them, creating
__Amen, one has to have kickback diodes to the rails to absorb that energy.
(Else, poof goes the pin)
Leikhim and Associates