Tree, I would be out of luck without my noise canceling device, in this case a
DXE NCC-1. Although my QTH is on a hilltop in the middle of 10 acres out in
the country, the property is surrounded by rural power lines in every
direction. I am about 200' above most and can see them from my antennas.
There are 4 or 5 noise sources; fortunately many times only one is active at a
time but there is at least one active a high percentage of the time.
When there is only one source active, the NCC-1 does a great job if both
antennas can hear the noise. My first use of the box was to feed port A of the
NCC-1 with the main tx antenna, via antenna feedthrough during receive on the
FT5K. Port B, or the noise antenna, was my Hi Z Triangle array. This combo
worked on all bands except 6 meters and frequently noise that was wiping out
the band could be nulled completely out. There were a few cases where my Hi Z
did not hear the noise well enough so I was out of luck.
Recently I installed some additional low band receive antennas for testing and
reconfigured my NCC-1 setup. There is a 600' standard beverage NE and a JK
BevFlex4 configured at the moment as a bog, running NE/SW bidirectional. There
are 5 KD9SV single direction bogs deployed in various other directions. Bogs
are used because my rugged terrain and driveway layout are just not suited to
beverages. These are my first bog attempts and they work much better than I
expected. I am still configuring the antenna switching system but the way it
is now allows the following combos:
Hi Z Triangle alone
600' NE beverage alone
350' south bog alone
250' west bog alone
350' NW bog alone
230' east bog alone
270' SE bog alone
NE/SW JK BevFlex4 alone
NCC-1 combination of the Hi Z triangle with one of the last 3 bogs listed.
The manual for the NCC-1 says best results in combining antennas for signal
enhancement occurs with similar antennas on both ports but I am finding many
occasions where combining the triangle with one of the bogs results in a signal
enhancement compared to either antenna alone. Not just a signal to noise ratio
improvement, but an actual increase in signal S meter reading. In the cases
where this works it is possible to adjust the NCC-1 for a null in the signal
and then flip the B Phase switch for a peak.
In the current configuration, the system still functions for nulling power line
noise if there is only one noise source active. Sometimes my noise and the
signal direction is the same; in this case nulling the noise also knocks down
the signal. Most of the time I can find some combination of antennas.
My next move is to add another Hi Z rx antenna relay switchbox to the mix,
which will allow phasing the Hi Z triangle with all the other receive antennas
which currently are stand alone.
Another option I would like to pursue is configuring a few of these bogs
running in the same direction but spaced/staggered to allow phasing through the
NCC-1. I suspect, based on results so far, this would be a worthwhile
improvement.
No attempt has been made yet to optimize the bog lengths. I did the on-ground
wire measurements with my SARK to calculate the shortening factor due to ground
proximity, and studied IV3PRK, K1FZ, K9YC, K2AV online literature. My ground
conductivity is poor, being on a rock cliff. The present lengths all show good
directivity on 80 and 160 plus seem to work on 40 to some extent.
I really need two of these NCC boxes in the shack, one configured as the first
was originally to allow phasing a noise antenna with the main tx antennas on
the upper bands, with the second dedicated to the current low band rx antenna
phasing for signal enhancement and noise reduction.
What is needed most of all is for AEP to fix my power line issues, which are at
times severe. This is a very quiet location when the power lines are not
singing. I invested in a two band VHF/UHF portable yagi and a Kenwood TH-F6
all band/mode receiver and can stand in my front yard and point to each noise
source when it is active. I can see the noise source poles. The AEP engineer
spent most of a day with me, and I pointed out where the noise locations were.
Apparently, he was never able to get a field crew assigned to do the work and
due to personal issues, I was unable to follow up with him or push for a
resolution. I am about to revisit the issue with AEP and hopefully can get
some satisfaction this time.
My Hi Z triangle is a great antenna but these bogs supplement it nicely. Wish
I would have tried bogs a few years ago.
73 Charlie N8RR
From: Topband <topband-bounces@contesting.com> on behalf of Tree <tree@kkn.net>
Sent: Saturday, December 3, 2016 8:01 AM
To: 160
Subject: Topband: New use for Noise Canceling box
Last night - around 8 PM or so - this HUGE noise signal showed up on 160 -
sweeping up the band slowly. Probably a DC power supply with signals every
80 kHz or something. But - it has some energy all over the ban - thus
rasing my noise floor. Sorry if I was an alligator last night.
I put a Beverage up to the East just before the contest started - so I had
two RX antennas - the other being a Hi-Z 4 square. The Hi-Z said the noise
signal was East - perhaps a bit stronger in the South direction than North
- so call it just South of East. The Beverage picked it up very well - so
it agreed. A feeble attempt at DFing last night was unsuccessful - but
will be tried again if it stays on during the daytime. It is still on this
morning before Sunrise.
The nasty part of the noise is about the same signal strength as most good
signals coming in that are not local (looking at the band scope). It has a
10 kHz or so wide peak.
I was able to put the two RX antennas into a MFJ-1026 - with the output
going to the RX input of my K3 - and adjusted the controls to null out the
noise. With a local signal - I have been able to obtain deep nulls and
this proved to be true with this noise. I was actually running guys on the
East coast right in the middle of the worst part of the noise after doing
this.
This technique would likely be useful for those who have a similar noise
situation - so I wanted to share. You obviously don't need a beverage for
the "noise" antenna - just something that is good at picking up the noise
and perhaps nothing much else. If you have a neighbor that has a noisy
device - just put something that is close to their house.
It's a battle out there to keep your noise sources under control. I'll
report back if I am successful in finding this one.
73 Tree N6TR / K7RAT
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