[ARC5] AN/ARC-5 on MF 630 Meters

[Hubert Miller]

This assumes the station is the traditional setup where there is a radio shack or radio room and the antenna leadin drops right to that location.
I would guess that this is no longer the predominant situation. If the antenna is a vertical or mostly vertical and the base is for example out in the
backyard, you will have to use coax to there and dispense with antenna loading inductance in the transmitter and also correct for the low impedance
output system of the transmitter to its load coil.
The only thing I have read about LF antennas in the last few years that really piqued my interest was an article in QST, where the writer found that
connecting the load coil right to the ground system, and feeding the antenna between this top of the load coil and the antenna. Instead of the traditional
connection where the coax goes to ground and the bottom of the load coil. The article reported this resulted in a noteworthy increase in radiated signal.
As I write this I am now wondering if maybe the feedline had to be balanced, open wire or twinlead, but I don't want to look up that article right now.
I'll remind myself to look at that article again.
-Hue Miller


>Something to bear in mind as one works on transmitting gear for 630 meters:

Much surplus and vintage gear was not intended for a 50-ohm load.  They originally worked into short-for-the-wavelength antennas, and most of us will be using just that sort of antenna for our ham operations.  So there may not be any good reason to convert the transmitter's output to drive 50 ohm loads, just to then have to build a matching network to raise the antenna resistance to 50 ohms.

You can read and see some of my experiences on my website at

http://www.wd8das.net/630m.html

I also wrote an article for QST, which can be read here...

http://www.wd8das.net/630mPractical.pdf

And I have a video presentation posted here...

http://www.wd8das.net/HamExpo/630mPractical.mp4


Steve WD8DAS


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