Mike
I have taken the liberty of changing to subject line to more accurately
reflect the content of your reply on the Waller Flag thread
After much reading and a lot of personal experience and experimentation
I am of the opinion that BOG front-to-back is a function not only the
length but the soil type as well.
I experimented with 350', 300', 250', and 200' long bogs all in the
same direction, In my case the shorter 200' long BOG, over very dry ,
well drained, sandy soil clearly had better F/B than the 250' , 300',
350' ( F/B on the 350' was the worst of all of them..anyone want some
50' pieces of RG6?) . When I run out of other things to do I plan on
trying a 175' and 150' but not in the next year.
A friend of mine living in another part of the country compared his 200'
BOG on laid top of rich Midwest farm loam to mine and was very
surprised that my front to back was so much better than his. What the
optimal length is for his particular soil is still TBD. Another friend
with sandy soil but in a very near salt water environment ( he lives
along a canal with ocean access, i.e salt water) also reported poor
front to back , for sure we surmise his soil is much more conductive
than mine) .
The moral I guess is I would start shortening your BOG and see if the
front to back improves
Dave
PS: I too use RG6 for all my BOGS and the feedlines and a dozen or more
turns on a #31 torroid at each end of a 125' feed lines significantly
reduces broadcast band induced signals
On 9/12/2020 8:26 AM, Mikek wrote:
My Technical knowledge is limited but, I have built directional AMBCB
antennas. Feed line isolation is critical to make a directional
antenna, directional! I have been criticized and been told, coax cable
does not pick up signal. Must be I don't use the right coax.
This from a previous post I made after I ran out and tested a 230ft
Coax and a 230ft 18ga twisted speaker wire, to see what BCB stations
they received.
"I found I received 13 stations with up to 5.5 S units on the
properly terminated coax. I tried many things to reduce signal pickup,
chokes, transformers, grounds, several chokes and transformers, but
could never get it to be quiet. So after reading some info about
phased antennas using speaker wire, I ran a twisted speaker wire out
to where my antenna was to start.
After terminating that, I found I only received 4 stations, 3 were
audible but at zero on my S meter and one that was almost 1 S unit.
Do I think the speaker wire has more loss than the coax probably, but,
I seem to have plenty of signal and it doesn't have much
signal ingress compared to the coax."
I have since went to Cat5 cable for my receive antenna. I started in
my haste just connecting Cat5 to my radio, terrible idea, but I
learned from it.
I tried several things to quiet the Cat5 and came up with something
that works very well for quieting the Cat5 in_MY_ situation.
I have the 235ft of Cat5 connected to a 260ft (property limited) BOG
that I use mostly for the AMBCB. The BOG points N/S, it seems to have
attenuated side lobes but not much front to back.
After reading a Laird Cat5 common mode article, I used their info to
help me build my signal ingress reduction box. If you're interested in
seeing what
worked for me, click here.
https://www.dropbox.com/s/e1lq7fxv0kggi5d/bog%20final%20design%20may%2030%202020%20common%20mode%20attenuator.jpg?dl=0
KF4ITA Mike Knowlton
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Dave Manuals@ArtekManuals.com www.ArtekManuals.com
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