A 40m Vertical

Let me first say I make no claims of originality for this item. It is intended as a simple, inexpensive solution for the newcomer to experiment across the 40m band (7.0–7.2MHz) when only restricted space is available. “A picture speaks a thousand words” so by including a couple I’ll keep it as short as possible!

With the rally season upon us, it is an ideal time to pick up those bits and pieces with which to experiment. The antenna described here consists of a 50R coax fed, inductor loaded 5.44m vertical section mounted on a 1m alloy tube driven into the ground and requires no radials although this may well depend on the local soil structure.

The vertical itself is a salvaged unit (probably ex. CB) consisting of 4 telescoping aluminium sections with an extended length of 5.44m and its mounting bracket.

The thick wire in the picture is the coax centre connection from the bracket mounted SO239 connector to the coil.

The coil is of open air construction, 19 turns of 18 gauge copper wire equally spaced over a length of 72mm with an inside diameter of 63mm and with the coax centre connected 9 turns from the antenna end of the coil and to the opposite end of the coil. I know this may seem strange but it works.

Connect to a transceiver, check the SWR and if necessary adjust the antenna length or coil tap slightly and away you go, it’s that simple!

With the antenna set to resonate at 7.1MHz I found there was little need for adjustment by the internal ATU of my TS2000 or FT1000MP-MkV to cover the entire band.

Copyright David Barber G8OQW

c. G8OQW (06/03/06)

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