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A REWARD OF 500 MICROFARADS IS OFFERED FOR INFORMATION LEADING TO THE ARREST OF THIS DESPERATE CRIMINAL: HOP-A-LONG CAPACITY. THIS UNRECTIFIED CRIMINAL ESCAPED FROM A WESTERN PRIMARY CELL WHERE HE HAD BEEN CLAMPED IN IONS AWAITING THE GAUSS CHAMBER. HE WAS CHARGED WITH THE INDUCTION OF AN 18 TURN COIL NAMED MILLIHENRY WHO WAS FOUND CHOKED AND ROBBED OF VALUABLE JOULES. HE IS ARMED WITH A CARBON ROD AND IS A POTENTIAL KILLER. CAPACITY IS ALSO CHARGED WITH DRIVING DC MOTOR OVER A WHEATSTONE BRIDGE AND REFUSING TO LET THE BAND-PASS. IF ENCOUNTERED, HE MAY OFFER SERIES OF RESISTANCE. THE ELECTROMOTIVE FORCE SPENT THE NIGHT SEARCHING FOR HIM IN A MAGNETIC FIELD, WHERE HE HAD GONE TO EARTH. THEY HAD NO SUCCESS AND BELIEVED HE HAD RETURNED OHM VIA A SHORT CIRCUIT. HE WAS LAST SEEN RIDING A KILOCYCLE WITH HIS FRIEND EDDY CURRENT WHO WAS PLAYING A HARMONIC.
For Those Who Understand, No Explanation Is Necessary. For Those Who Do Not Understand, No Explanation Is Possible. WD5DBC
THE DOCTOR IS IN
Excerpted from: Question -- Ray Fritts, KA8SYX, of Jacksonville,
Florida, asks: If a The Doctor Answers -- Your calculations are right on. That's all there is to it. But do keep in mind just a few potential pitfalls: Published cable loss data is for new cable. If used indoors in a non-hostile environment, it will stay close to new for many years. If the jacket allows moisture or moisture vapor to penetrate, it can degrade from subsequent corrosion. I have been amazed to find that the copper in some old cables that have been used outdoors has turned black from corrosion, and likely is no longer acting like a shield at all. You are correct that the loss increases with an SWR higher than 1:1. For your receive case, keep in mind that the SWR is determined by the input impedance of the receiver -- not the antenna impedance. Sometimes receivers aligned for minimum noise figure do not have an impedance of 50 Ohms. Check your receiver specs. Do you have a question or a problem? Send your questions to or to "The Doctor," ARRL, 225 Main St, Newington, CT 06111 (no phone calls, please). NEXT SOLAR STORM CYCLE
WILL START LATE (excerpted from NOAA’S Space Environment Center release) The next 11-year cycle of solar storms will most likely start next March and peak in late 2011 or mid-2012 – up to a year later than expected – according to a forecast issued today by NOAA’s Space Environment Center in coordination with an international panel of solar experts. Expected to start last fall, the delayed onset of Solar Cycle 24 stymied the panel and left them evenly split on whether a weak or strong period of solar storms lies ahead, but neither group predicts a record-breaker. The Space Environment Center led the prediction panel and issued the forecast at its annual Space Weather Workshop in Boulder. NASA sponsored the panel. “The Space Environment Center’s space weather alerts, warnings, and forecasts are a critical component of NOAA’s seamless stewardship of the Earth’s total environment, from the Sun to the sea,” said retired Vice Adm. Conrad C. Lautenbacher, Ph.D., undersecretary of commerce for oceans and atmosphere and NOAA administrator. During an active solar period, violent eruptions occur more often on the Sun. Solar flares and vast explosions, known as coronal mass ejections, shoot energetic photons and highly charged matter toward Earth, jolting the planet’s ionosphere and geomagnetic field, potentially affecting power grids, critical military and airline communications, satellites, Global Positioning System signals, and even threatening astronauts with harmful radiation. These same storms illuminate night skies with brilliant sheets of red and green known as auroras, or the northern or southern lights. Solar cycle intensity is measured in maximum number of sunspots – dark blotches on the Sun that mark areas of heightened magnetic activity. The more sunspots there are, the more likely it is that major solar storms will occur. In the cycle forecast issued today, half of the panel predicts a moderately strong cycle of 140 sunspots, plus or minus 20, expected to peak in October of 2011. The other half predicts a moderately weak cycle of 90 sunspots, plus or minus 10, peaking in August of 2012. An average solar cycle ranges from 75 to 155 sunspots. The late decline of Cycle 23 has helped shift the panel away from its earlier leaning toward a strong Cycle 24. Now the group is evenly split between strong and weak. “By giving a long-term outlook, we’re advancing a new field—space climate—that’s still in its infancy,” said retired Air Force Brig. Gen. David L. Johnson, director of NOAA’s National Weather Service. “Issuing a cycle prediction of the onset this far in advance lies on the very edge of what we know about the Sun.” On the Web: NOAA: http://www.noaa.gov/ NOAA’s Space Environment Center: http://www.sec.noaa.gov
GOOD TIME TO CHECK With the advent of good weather (I do hope) HAMS usually (should)? check all their antenna installations. The winter weather can and does take a toll on coax, fittings, weather proofing, and antennae. One should be attentive to the “grip” of hose clamps, or whatever you use to secure the sections of the antenna. Likewise, the nuts and bolts of beam antennae can and do become loose and undependable. When we find what seems to be a tight grip of the clamp it’s a good idea to test it by grabbing each side of the clamp to see if we can twist it loose. We should not be able to do so!!!! (If you’re going to do this it’s a good idea to mark the proper place for the joint). Long wires, V-Beams, and vertical antennae, etc., are no less subject to the effects of winter. Neither is the “weather proofing” at the coax connectors. Tape may become loose, dry out, or unravel. So may the “gunk” deteriorate. Any moisture getting into the connection will be very bad for your signal, coming or going. Likewise, moisture creeping it’s way into the coax itself will do very serious damage. In my sad experience wet coax never completely dries out. It is good for nothing but to be stripped of the outer jacket, and to salvage the braided shielding for use as ground straps among the equipment in your shack. As a reminder: the antenna, with it’s feedline, is the most important part of your station. "BACKWARD SUNSPOTS"
MAY HERALD START OF SOLAR CYCLE 24 Excerpted from: The recent appearance on the sun of two
so-called "backward sunspots" may mean solar Cycle 23 is drawing to a
close and Cycle 24 now is under way or soon will be. At least that's the
thinking of some scientists. * * * * * *
BATTERIES Secondary
Type (Rechargeable) Lead
Acid: Variety
of capacities 1 to 500 Amp hours. Voltages
6 or 12 volts. Two
major types: liquid filled or gel. The
best type for use with ham equipment is the gel cells.
There is less of a chance for a acid spill. These
batteries like to be kept fully charged. If
the batteries are stored discharged the plates will passivate and this will
destroy the battery. Easy
to maintain and best buy based on amp hours per dollar. Capacity loss is low in
storage. Nickel
Cadmium: One
of the most commonly used batteries. Voltage
is 1.25 working voltage, end of charge should be 1.45 to 1.40 vdc. These cells
have very good cycle life (>1000 cycles normally). The
only problem with Ni-Cad cells is the memory effect.
This effect can be erased by total discharging the batteries and shorting
them down using resistors, then recharging. Capacity loss is 1% per day of
remaining capacity in storage. Should be stored cold about 40 deg. F. Nickel
Metal Hydride: Very
common cell. Voltage is slightly higher than Ni-Cads.
They have more capacity than a Ni-Cad.
The charge voltage should be 1.55 at the end of charge.
These cells like to be used. They
have a lower depth of discharge capability than Ni-Cads.
The cycle life is very good (>1000 cycles normally). The down side to these cells is the higher cost and the
higher rate of self discharge. Their
self discharge rate is 3% per day of remaining capacity. In other words charge them and then use them. Lithium
Ion: One
of the new battery types. The
working voltage is 3.00 to 4.2 vdc. These cells need
a special charger to charge them properly.
This type of cell should not be totally discharged.
The lowest cell voltage should not go below 2.5 volts under load. If you short the cells or try and charge them backwards the
cell has a protection device built in. If
the protection device is a fuse or the fuseable separator is tripped the cell is
destroyed. The cycle life of these
cells is limited (<1000 cycles). The
self discharge rate is very low. These
cells can be disposed of by throwing them away. The chemicals are very low in toxicity. Lithium
Polymer: New type of battery. The battery is made of two types of plastic plates that are pressed together. There is no electrolyte in the pack. They are very flat and light weight. The working voltage is 3.00 to 4.200 vdc. These also need a special charger to charge properly. They are normally used for low current applications. They have a very low self discharge rate. The cycle life is limited on these cells (<1000cycles). ED
NOTE: Mike has 20 years experience in the battery lab (Power Sources Lab) at
Lockheed Martin. He knows whereof he writes. This information is very valuable
to Hams when selecting HTs and batteries. |
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