I have been asked how I arrived at the 290 foot BOG length.
My original 200 foot BOG had a good F/B on 80m but showed almost no
directivity on 160m, so this indicated to me that the BOG needed to be
longer to improve the 160m performance with my particular soil conditions
and environment.
A search on the Internet produced recommendations for 160m BOG lengths of
247 to 290 feet. Knowing that I could always shorten the wire, I went with
the longer number as a starting point. That produced a greatly improved 15
to 20 dB Front-to-Back ratio.
The 290 foot length was not chosen for a good match, but that length just
happened to result in a good match.
Unfortunately, I did not measure the match on my 200 ft BOG before it was
dismantled.
The optimum 160m BOG length in your environment might be much different from
what I found at my QTH.
- - - I think the group would benefit from hearing what others have found to
be their optimum BOG lengths - - -
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Lloyd -
N9LB
Sent: Sunday, October 16, 2016 11:06 PM
To: 'Topband' <topband@contesting.com>
Subject: Re: Topband: BOG
My Reversible Bog uses the KD9SV transformer set. It was originally 200
feet long, just increased to 290 feet and that made a very significant
improvement on 160m front-to-back ratio, but hurt 80m performance.
Conditions here are:
Wire run across a weedy field, as close to ground as possible (weeds
trampled down to allow the wire to be close to ground - mostly 2-4 inches
above the actual ground). Soil is a few inches of decent dirt, about one to
two feet of clay, about one to two feet of sand, and then bedrock. Tops of
the five foot ground rods can't be driven completely below the ground's
surface.
WX - a wetter than normal Summer and Fall here in Southern Wisconsin.
My Antenna Analyzer shows a 1.45 : 1 match at 1825 KHz ( 75 ohm system ).
I can send the analyzer plots to anyone that is interested.
73
Lloyd - N9LB
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Charles
Moizeau
Sent: Sunday, October 16, 2016 10:20 PM
To: Lloyd - N9LB <lloydberg@charter.net>; Topband <topband@contesting.com>
Subject: Re: Topband: BOG
Thanks Lloyd,
But pls tell us your wire height and approximate description of gnd condx
for your otherwise well-described bog.
73,
Charles W2SH
________________________________
From: Topband <topband-bounces@contesting.com> on behalf of Lloyd - N9LB
<lloydberg@charter.net>
Sent: Sunday, October 16, 2016 7:15 PM
To: topband@contesting.com
Subject: Re: Topband: BOG
Hello Tony!
Ground conditions and wire height above ground make a huge difference in
best length.
I found the optimum for my BOG, using WD-1A wire and operating at 1825 KHz,
at my QTH is 290 feet.
73
Lloyd - N9LB
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of N2TK,
Tony
Sent: Sunday, October 16, 2016 5:15 PM
To: topband@contesting.com
Subject: Topband: BOG
Stretched out 200' of WD-1A along a stone wall. Kept it about 2" above the
ground and right up against the stones. Fed it with a 300 ohm secondary
transformer and left the far end unterminated.
Used the MFJ-259 to sweep the bands starting at 1.67 MHZ. Saw on K1FZ notes
that to find the best single wire length for 160M is to sweep the bands and
check where the SWR goes to a low value and stays there.
I couldn't find that frequency. I get dips at
2.58 MHZ 4.3:1
3.36 MHZ 1.5:1
4.39 MHZ 1.4:1
6.033 MHZ 1.3:1
9.807 MHZ 1.2:1
I didn't check any higher in freq. I only care about listening on 160M with
it.
I twisted both wires together at the feedpoint.
Want to check it out first as a single ended BOG to see how it works before
I go to the trouble of making it a two direction BOG.
At one point the BOG is only 35' from my tower.
Is it too high and does it need to be against the ground?
Any feedback appreciated.
N2TK, Tony
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