Topband: Topband Digest, Vol 165, Issue 3

[Warren Merkel]

Gale,

I believe the BOG would appear to be bi-directional without termination,
however you lose most of the benefits (RDF) of the BOG using it that way.

As with the Beverage, the BOG has maximum reception in the direction of
the end having the resistive termination.

See my QRZ page for details in construction of modules that are easy to
build that allow you to make a reversible end-fed system with RG6.

https://www.qrz.com/db/KD4Z

Clicking on each diagram will open a larger detailed version

In particular, you need to build one of these End-Fed modules:
https://dl.dropboxusercontent.com/u/24789865/BOG/BOG_KD4Z_Feedpoint%20Endfed_%28ver4.0%29.png

and a reflection transformer module as shown in the left side of this
graphic:
https://dl.dropboxusercontent.com/u/24789865/BOG/BOG_KD4Z_Reflection_%28ver3.0%29.png

In the feedpoint module, I used a Bias-T type arrangement to send the DC
reversing voltage out to the relays in the feedpoint module.  You can
simplify it by not using the RG-6 feedline itself for relay control,
eliminate the capacitors and choke, and just run a separate pair of
wires to actuate the reversing relay.

Since you are only interested in one direction with the feedpoint at the
NE end, you could remove both of the relays and one termination resistor
(the upper one in the diagram). However, you would need to wire it as if
the relays are energized and you must use a reflection transformer at
the SW end.

In your case, the BOG would be permanently reversed, with the captured
signal exciting the RG6 shield as the wave travels from NE to SW.

At the SW end, the reflection transformer transfers the captured signal
to the center conductor, where it is sent back towards the feedpoint at
the NE end, to be detected by the 1:1 transformer between the RG6 center
conductor and shield.

For 160m, you need at least 180-200 feet or more of RG6 for the BOG itself.

Don't forget about Common Mode rejection, a must for this type of antenna.

ON4UN's book, "Low-Band DXing" is a must-read for further details.

73 de KD4Z
Warren

On 9/7/2016 12:00 PM, GALE STEWARD <k3nd at yahoo.com> wrote:

> Date: Wed, 7 Sep 2016 15:18:28 +0000 (UTC)
> From: GALE STEWARD <k3nd at yahoo.com>
> To: TopBand List <topband at contesting.com>
> Subject: Topband: BOG Question

> I'm thinking of trying a BOG as I could run it across the corner of my neighbor's field (after he's finished mowing for the season.)
> My questions are:
> Can a BOG be used un-terminated and is it then bi-directional, as is a conventional beverage?
> In a terminated BOG, is the maximum received signal direction into the terminated end or into the feed transformer end?
> The reason for these questions is that I could easily position the BOG to the EU direction but the feed point end needs to be at the NE end (toward EU). It's not possible to run a feed line across the end of the field to the "far" end of the BOG.
> I didn't see these issues addressed in anything that I could find online.
> Any info appreciated...
> 73, Stew K3ND