background preloader

eHam.net

eHam.net
Related:  Amateur Radio II

How to Use Your Antenna Tuner Just a few comments and corrections. "Say the antenna tuner is rated at 300 watts. OK, 300 watts at what impedance and reactance? Nope, that's not in the manual!" Well, it is in SOME manuals. "If you try and match very low impedance of say 15 ohms with that so called 300-watt antenna tuner with 100 watts the capacitors and switches will arc over from the several thousand volts developed across/through them. That a little bit of an exaggeration. Using about 200pF and the full capacitance at at power of 100 watts, we have 1600V on 3.5 MHz and 224V on 28 MHz. Now here is what is interesting. In a conventional T network the less capacitance used, the higher the voltage and loss. The worse place for using tuners is with a LOW impedance on low frequencies, and you should ALWAYS tune for maximum capacitance. "some type of Balun. Tuners are wisely getting away from 4:1 baluns now and using 1:1 baluns. "Simply connect the meter to the Balun. Not really. " What you need is an external 1:1 Balun. ".

About Us - National Capital Radio & Television Museum The National Capital Radio & Television Museum operates in Bowie, Maryland, and also curates continuing exhibits elsewhere. Opened in 1999, the museum is open to visitors three days a week. Explore radio from Marconi’s earliest wireless telegraph to the primitive crystal sets of the 1920s, from Depression-era cathedrals and post-War plastic portables to the development of radio with pictures (a.k.a. television). This website details what we do, the services we offer, and the extensive benefits of museum membership.

Building the baseplate The baseplate is made of a 12 inch square type 6061 T6 aluminum plate that is 3/16 inch thick. This particular type aluminum is harder than pure aluminum and less likely to bend while being resistant to weather. U-bolts attach the spreaders to the baseplate.Two square base floor flanges normally used for handrails are used to mount the center post to the base plate. One is on the top for mounting the center post and the other is on the bottom for insertion of the mast. These flanges are made of aluminum-magnesium alloy.Stainless steel hardware can be used to minimize corrosion especially in saltwater environments although it is more expensive. Hexagonal Beam by K4KIO Building the G3TXQ Broad Band Hexagonal Beam Buy or build a hex beam Six Steps to build it - The Base plate The plate can be cut with a hacksaw by hand or by a reciprocating saw with a metal cutting blade. Measuring and marking the hexagon. A metal hole saw and a hand operated drill can be used to cut out the center hole.

A homemade 5-band Hexbeam antenna J-F. Zürcher, HB9MCZ updated April 7, 2009: new broadband hexbeam After reviewing dozens of antennas, I was convinced that the hexbeam represents the best compromize in terms of performance, dimensions, weight and wind load. So I decided to make my own one ... if possible with some original contributions! [1] the excellent commercial version of Mike Traffie [2] a very detailed description of the construction of a hexbeam [3] a lot of informations by a "hexbeam fan" [4] understanding the hexbeam, with a lot of informations and simulations My main source of inspiration has been reference [2]. As I have access to various machines (lathe, milling machine, ...), I decided to make a "semi-professional" realization: a rigid central baseplate made of two aluminium plates (6 mm thick!) TDR measurement of the square feeding line (central post)

W8WWV Experimentation Antenna and Other Experimentation Greg Ordy, W8WWV In the early days of amateur radio, most amateurs built, and often designed, all aspects of their station. The transmitter, the receiver, and the antennas. While some amateurs still enjoy designing and building transmitters and receivers, most just buy a commercially-built radio. Antennas, however, still remain an area of active experimental design and homebrew construction. With the introduction of antenna modeling software, it is now possible to investigate antenna designs without resorting to their construction. The following links take you to antenna designs that have caught my interest. EZNEC. Search this site, or, the entire Internet! Notes: General:

Simple, Inexpensive Coax Connector Tool Simple, Inexpensive Coax Connector Tool from Joseph Lawrence, K9RFZ on March 14, 2013 View comments about this article! "Editor's Note: Due to the popularity of some of eHam's older articles, many of which you may not have read, the eHam.net team has decided to rerun some of the best articles that we have received since eHam's inception. These articles will be reprinted to add to the quality of eHam's content and in a show of appreciation to the authors of these articles." This article was originally published on: 11/30/2009 Simple, Inexpensive Coax Connector ToolBy Joseph Lawrence, K9RFZ I use a lot of PL-259 connectors to build feedline cables for friends and recent Technician hams that need some help getting on the air. I reused a PL-259 barrel and glued it inside a PVC T-connector with the threads pointed outward. Prep the coax as usual, but then thread the PL-259 connector into the new tool. Line up the connector on the coax and twist away. Member Comments: This article has expired.

HDSDR Homepage TAPR SolderSmoke Daily News XTAL Set Society W6SDO

Related: