[TowerTalk] 80m DX special dipole

[Herbert Schoenbohm]

Interesting approach and more reasonable than RG-213 hanging in the air
across the yard. My XYL loves the fact that my towers are placed at the
opposite ends of the property so our living room has a clear and
unobstructed view of the azure blue waters of the Caribbean.,  From tower
to tower there is a support for a classic 3.5 Mhz Marconi T which works
against a groud system.  It really works well for DX as long as I use
Beverages for RX. The only problem is that when the station is used in
contests by NP2P remotely and in contests that require both phone and CW,
This must be automatic and a remote tuner that will do 2KW is very costly.
There is no way to cover both CW and at least the low-end phone portion of
80/75 meters. Unlike dipole that can be broadbanded, I have yet to find a
way a suitable way to broadband a Marconi "T" vertical.  I do recall many
years ago that there was an antenna like this in a Military Antenna
Manual.  That manual has gone the way of Hurricane Hugo in 1989.  If I
recall it had a flat top with three instead of one vertical drop wire. One
drop wire was in the exact center and the other drop wires were each side
of the center by about, I think, 30%. All were fed together at the bottom
against a gound system. This was a through back antenna design from the
Marconi trans- Atlantic communications days, long before anyone had decided
to model antennas.

If there is anyone who can send me info on this I would appreciate it.  I
have never seen this in any amateur publications.

Herb Schoenbohm, KV4FZ


On Wed, Sep 12, 2018 at 6:58 AM Dan Maguire <danac6la at gmail.com> wrote:

> Jim Brown wrote:
> >>> There is, by the way, another very good way to broadband the match to
> a dipole to cover 3500 - 3900 and keep the SWR below 2:1. EE prof W6NL says
> the idea goes back at least 80 years.
>
> >>> Cut the antenna to about 3675 kHz and verify that it resonates there.
> Connect a half-wave of any good 50 ohm coax to the antenna, then add a
> quarter-wave of a good 75 ohm coax. If the combined length is too long,
> coil up the excess. If you need more coax to get to the rig, add any length
> of 50 ohm coax.
>
> AutoEZ users:  If you'd like to experiment with modeling this
> broad-band 80m dipole see the 4th section on this page:
>
> https://ac6la.com/aecollection5.html
>
> There is a link to download an AutoEZ format (.weq) model at the end
> of the section.
>
> Dan, AC6LA
> https://ac6la.com
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