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In this video Dave Tadlock KG0ZZ describes a $4 amateur radio dual band 145 / 435 MHz satellite antenna.
Watch the $4.00 Ham Radio Satellite Antenna video: http://www.youtube.com/watch?v=Hy_XwvMmIro
Details of the antenna are at: http://www.amateurradio.bz/4_dollar_satellite_antenna.html
ust a reminder that Wednesday 23rd April is
St George's Day and some Essex Hams will
be on the bands with the callsign GB1STG operating from Chelmsford in Essex.
Event organiser, Charlie M0PZT says: "We'll take any excuse to play radio and what better reason than the Patron Saint of England?.
We'll have a 40m station running for much of the day plus some CW/SSB and Digimode activity on the higher bands subject to conditions. We'll also have 2m FM."
Operating from Galleywood Common, 2km south of Chelmsford, the team are braving not only the outdoors but their supply of batteries.
"Most of us use 7Ah batteries for our solo portable efforts so we'll be dragging an 86Ah one to the site! Around 16 degrees is forecast with a little cloud, so we're hoping for a rain-free day." says Charlie.
There'll be updates on Twitter via Charlie's feed: http://twitter.com/M0PZT and Pete M0PSX from Essex Ham will be operating and covering the event via http://www.essexham.co.uk
More details via Charlie M0PZT : http://www.m0pzt.com?gb1stg
Bet you didn't know this! Mobile maven Alan K0BG notes, "Most automotive fuses are ATO. The difference is that the ATC (the C stands for 'closed') fuse element is completely sealed in plastic and the ATO (open) is not. Since [most radio] power cable fuse holders are not waterproof, only an ATC fuse should be used. If an ATO is used, and water gets into the fuse, the fuse element corrodes over time with predictable results." See: http://en.wikipedia.org/wiki/Fuse_(automotive)
Element sections getting stuck together are one thing but what about boom-sized pieces? Roger K8RI makes some suggestions about getting the pieces apart. "Clamp to each end of the boom. Hook one end to something solid and use a block and tackle or come-along off the other end to carefully pull the sections apart. The pull needs to be balanced so it pulls straight. There are many ways to clamp to the boom ends, such as using two [boom-to-mast] mounting plates each held with a pair of U-bolts...anything to allow a straight pull. The sections should easily pull apart although you might have to use some PB Blaster ( http://www.blastercorporation.com/ ) or similar product and let it soak...the clamps should not take much force. Just a cable loop anchored on opposite sides with the pull from the middle of the loop. Keep it simple and if it appears to look like it's going to take much force, stop and reevaluate. You might need to tap on opposite sides with rubber mallets to loosen things up. Do not use metal hammers. Apply hits to opposite sides at the same time. Do not hit hard.
How do you grab on to large-diameter tubing, anyway? Steve K7LXC says "I've found that a chain wrench is real handy when dealing with round objects like booms and masts." Be careful not to let the chain bear on a corner or edge - that will create a permanent dimple. https://www.ridgid.com/us/en/chain-wrenches
Tim K3HX sent a couple of good links to technical articles that may be of interest. The first is an EDN magazine article about measuring large currents ( http://edn.com/design/analog/4429901/Achieving-accurate-measurements-of-large-DC-currents- ) - perhaps like we need to do in the bigger solid-state power amplifiers or in mobile installations. Another Electronic Design article explains the difference between watts and volt-amperes, a key specification of large transformers - http://electronicdesign.com/energy/what-s-difference-between-watts-and-volt-amperes
Monday, 21 April, 2014
1056 The supernova in the Crab nebula was last seen by the naked eye.
1507 M. Waldseemuller, Germany, names 'Amerige' to the part of the globe, America.
1703 Edinburgh Fire Brigade, one of the first in Scotland, was formed.
1791 Samuel Morse born, Charlestown, Mass. USA.
1792 In Paris, at the place de Greve, the guillotine was used for the first time on a human.
1827 W R Hamilton presented his wave Theory of Systems of Rays at the Royal Irish Academy in Dublin
1865 SS Sultana exploded, 1450 - 2000 die. Worst in US history.
1900 Marconi International Marine Communication Company Ltd. formed
1900 Marconi Patent 7777 for tuned coupled circuits.
1915 Gallipoli Landings - an ill-fated but heroic campaign commenced.
1986 At 1:23 a.m. Ukraine, the Chernobyl atomic power station exploded.
Our thanks to John Alcorn, VK2JWA of the Summerland Amateur Radio Club