Topband: 40m array as RX antenna

[n4is at n4is.com]

Lee

I agree with you, a vertical array in a quiet place works very well, I
remember our friend Dale. The 8 circle array has almost 13 db RDF and can
hear better than the WF with 11.5db RDF.

The issue is city lot with tons of noise from everywhere. Small back yard
with all cables tower and other wires nothing vertical works there.  Several
contest stations have problems with beverages due to much towers.

Unfortunately situation is getting wroth every year, I am not using my
vertical WF anymore, the noise level with LED and Variable speed motor
drives, is becoming unbearable on the city. Friday and Saturday people here
charge the battery of their boats to enjoy the weekends at the sea, what a
mess, noise from everywhere. The noise on my vertical antenna is s9 during
the week and s9+10 during weekends.

EWE, loops and flags need low NF and good shield. I am just reporting what I
see helping people to install WF's. Most station have serious problem with
common mode noise.

I would suggest a metal box to protect any RX system, it does help.  

You never know what you are missing if you have nothing to compare with. I
understand price point is always an issue.

Regards
JC    
N4IS



-----Original Message-----
From: Topband <topband-bounces at contesting.com> On Behalf Of lee at k7tjr.com
Sent: Wednesday, November 14, 2018 6:28 PM
To: 'topband' <topband at contesting.com>
Subject: Re: Topband: 40m array as RX antenna

 JC thanks for helping Jamie,
I agree with most things you have pointed out however I must take issue with
you on never use plastic boxes. I have used plastic boxes on my arrays for
many years now and it has been very successful. The decision to use a
plastic box or not depends mostly on the signal levels expected in the
circuitry. My take on this is that the Waller flags have a very low signal
output which requires extreme low noise and high gain amplification. The
phased vertical arrays such as I make have a much greater signal output
level and have never shown any ill affects using plastic. There is no need
for my customers to go on a mission to change all their arrays to metal
boxes.
   As far as DX is concerned I wish my very good friend Dale N4NN from
Florida was still around because he and I would compare what you were
hearing and what he was hearing. He always reported to me he would hear
everything you did with his Hi-Z 8 array. I suspect the difference as you
say was he was in the country without a lot of vertically polarized noise
where your recording clearly indicate considerable power line noise on your
VWF compared to your HWF.
   Eliminating local noise is quite a process of peeling back the layers one
at a time. Without any other tools your best noise finding friend is a small
transistorized BC band radio. It is amazing what you hear when you place one
near different powered objects in your area. Put one next to your TX antenna
and you will find noises and signals that are reradiated. Put one next to
your computer monitor and you are likely to faint.
   The biggest problem we see is RG-6 coaxial cable that has been
contaminated and the shield connection is damaged. To a great degree that
causes all directivity to be compromised as the array then electrically
looks just like a bunch of wire laying on the ground. Interesting that you
indicate some  say front to back does not affect RDF but this I will assure
you, if you have an array that does not show significant front to back you
can be rest assured the array will not have much RDF.
    The writings of Jim K9YC are very valuable for knocking down local noise
in any RX antenna. He has addressed this many times.
 Keep us posted Jamie if you need more information.


Lee   K7TJR
Hi-Z Antennas



Hi Jaime

The only way to really improve signal to noise ratio is with directivity.
Better directivity better signal to noise ratio. Everything else is just
less deterioration or more deterioration. The only thing that makes a
difference is how narrow the front lobe really is.

Your 40m array plus the integration with your tower and inverted L is giving
you a better directivity. Probably if you try another direction the results
should be very different. 

Things that people believe but does not impact signal to noise ratio.

1- Front back. 
2- Noise canceling  devices , (only help with weak signal it its narrow the
front lobe)
3- Vertical array, if you live downtown, or a city  lot like mine, 150x 100
ft back yard. The manmade noise is only vertical polarized, vertical array
may help you to hear more noise.

If you want your vertical RX array to work, it is necessary to detune your
TX antenna, and any other vertical structure above 1/8 wave high, even it is
300 ft away. 160m one wave length is 480ft long, don't full yourself.

Get common mode out of your RX system input, good shield is a must, never
use plastic box for any RX system part. Open frame relay is also a big
problem, DC bringing noise to the amplifier, another thing. Choke and shield
is your friend, but only works with a good ground.


RDF measure directivity, more RDF better reception, but every single wire ,
cable, tower can deteriorate RDF, you need to control that.

You can hear my webinar at WWW.WWROF.ORG 

>> https://wwrof.org/webinar-archive/n4is-waller-flag-construction/

>>
https://wwrof.org/webinar-archive/high-performance-rx-antennas-for-a-small-l
ot/

Just an update from that Webinar . NX4D using a Waller Flag from a 1/5 acre
lot is now at #311, confirmed on 160m. 

My Horizontal Waller Flag, HWF, is working very well, I can hear 4K6FO , FR
, VU almost every time they are on the band.. I Heard 316 countries on 160m
since 2006, but the HWF was operational only after 2010. Now I am  at #299
on 160m.

This is a thing people only believe when they see it happening. Almost 100
people is using WHF and VWF around the world, all of them delivering
excellent performance. However it is a huge project, not plug an play at
all, and it works!

73's
JC
N4IS





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