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KB6NU's Ham Radio Blog
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Three from Twitter: OCF dipole covers 40-6 meters, generate your own
azimuthal map, build an all-band receiver with an Arduino
Posted: 04 Jul 2021 07:17 AM PDT
http://feedproxy.google.com/~r/kb6nu/tVpu/~3/kxb6bV7nzqI/?utm_source=feedburner&utm_medium=email
OCF dipole covers 40 6 meters
Dimensions are in meters. The balun at the feedpoint is a 4:1 balun.
I dont usually plug products here, but I thought that this M0CVO off-center
fed dipole was a clever design. Not only that, it can be easily built by
the homebrewer. According to M0CVO,
The HW-42HP is an Off Centre Fed Dipole with a difference. Designed to operate on all bands from 40m (7MHz) 6m (50MHz). It will operate on 40,
30, 20, 17, 15, 12 and 10m without an ATU (SWR <3) plus 6m with an ATU. It is also possible to operate on both 80m (3.5MHz) and 60m (5MHz) via a good ATU. This will handle 400W key down or 500W PEP.
Having a feedpoint 1/3 of the way along gives a feedpoint impedance of 200ohms. This is not ideal for modern day transceivers requiring an
antenna with a 50ohm impedance. Therefore, a 4:1 balun is added at the feedpoint to alter the impedance to something closer to the 50ohms
required. This then allows the antenna to be fed using standard 50ohm
coaxial cable such as RG8 or RG213.
The overall length of the antenna is 20.28m or 66ft. It may be mounted horizontally, as a sloper or as an inverted vee. If space is at a premium
it may also be bent to fit in with no loss in performance.
Generate your own azimuthal map
NS6T has made available an online azimuthal map generator, and its very
cool. Heres an azimuthal map centered on my location in Ann Arbor, MI.
To generate a map, all you have to do is to input your grid square or
latitude and longitude, but wait, theres more! You can also specify a
distance from your location to get a smaller map, and have it include grid squares.
Build an all-band receiver with an Arduino (and an Si4735)
Heres an interesting project that looks relatively simple to build. It uses
an Arduino to control an Si4735, which is a fully-integrated, 100% CMOS AM/FM/SW/LW radio receiver on a chip. DigiKey has them for $18. You could probably build a complete receiver for less than $50.
This video shows some enhancements that Mirko has added to the software,
but there are links to oprevious videos describing the original project.
The post Three from Twitter: OCF dipole covers 40-6 meters, generate your
own azimuthal map, build an all-band receiver with an Arduino appeared
first on KB6NUs Ham Radio Blog.
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