Saw the comments on adding radials, so I had to comment on my
situation this year.
I didnt get around to rolling out the 27 radials ( 30'-130' long
depending on PL) yet, so I entered the ARRL 160 Contest with just my
trusty single ground rod near the base of a walnut tree.
(During lawn mowing season, I coil up my radials and hang them from
the lower limbs of a 40 ft tall walnut tree near the NE corner of a 3
acre yard, all of which needs mowing. ).
This year, due to a family conflict on Sun (today) I had to limit my
operating to Day One
Station: IC-7610 -ACOM 1000+ N1MM Logger + SAL-30 rx antenna.
Conditions were quite good with even a fair bit of EU DX to be had. My
N1MM+ log shows 539 QSOS's and 88 mults on Day One. Things were so
good that among my first hour I had DE and ND in the log. Being an OG
( old goat) a few days away from my 80th birthday, I definitely need
more periodic breaks, naps from the operating position. Those
amounting to 4.5 hours out of the first 13.5 hours, before I pulled
the plug at 3:30am after the rate slowed way down, as did my adrenalin
level. I napped for two hours, then put in another 90 minutes prior to
SR. That was it for me. Never could muster the energy needed for a
second night.
But the 160 contest is good for roaring starts, and this year was no
exception with 131 Q's during the first two hours. As is my wont, I
find a quiet spot usually between 1800-1810khz and CQ away. It never
ceases to amaze, that you can CQ three times in a row with no takers,
but on the 4th you get 3-4-5 replies. :). While the entire contest had
good solid sigs and plenty of them, I found a 2nd peak around
midnight-2 am where things really caught fire, for some reason.
I may forever wonder "What IF" had I mustered the energy for my usual
Day Two, but at least I had a good time of it while I lasted.
And all that with no radials and a single ground rod, on a plot of
land that was former Ohio farm land. SWR was 1.0:1 at 1830, and
remained below 2:1 up to 1890 khz. Now when I DO uncoil my radials, it
definitely shifts resonance and raises SWR. So my soda bottle shunt
inductor gets played like an accordion to bring it back down.
Plus, this year my usual UNUN was also out of the circuit.
Despite all of the above, I really didnt see any significant
difference in performance. So I have to agree, that a couple of extra
radials here and there would be impossible to detect at the other end.
PS My own rule of thumb on radials is to keep adding them until I see
no further change in SWR - which increases as I add radials - compared
to a naked ground rod.
-----------------------------------------From:
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To: topband@contesting.com
Cc:
Sent: Saturday December 4 2021 12:00:57PM
Subject: Topband Digest, Vol 228, Issue 4
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Today's Topics:
1. More radials towards EU (Ignacy Misztal)
2. Ground loop isolator that passes DC (Chuck Hutton)
3. Re: Ground loop isolator that passes DC (Jim Brown)
4. Re: Ground loop isolator that passes DC (Don Kirk)
5. Re: Ground loop isolator that passes DC (Richard Thorne)
6. Re: Ground loop isolator that passes DC (Jim Brown)
7. Re: More radials towards EU (John Kaufmann)
8. Re: Ground loop isolator that passes DC (Andrew Ikin)
9. Re: Ground loop isolator that passes DC (Frank Krozel)
10. Re: Ground loop isolator that passes DC (Jim Brown)
----------------------------------------------------------------------
Message: 1
Date: Fri, 3 Dec 2021 13:15:33 -0500
From: Ignacy Misztal
To: topband@contesting.com
Subject: Topband: More radials towards EU
Message-ID:
Content-Type: text/plain; charset="UTF-8"
My shunt fed tower has 36 radials 70 to 100 ft long. Would adding a
few
longer radials towards EU help to EU?
Eznec says no.
Ignacy NO9E
------------------------------
Message: 2
Date: Fri, 3 Dec 2021 20:32:37 +0000
From: Chuck Hutton
To: "topband@contesting.com"
Subject: Topband: Ground loop isolator that passes DC
Message-ID:
Content-Type: text/plain; charset="iso-8859-1"
Hi -
Many years ago I saw some ground loop isolators that pass DC.
That is exactly what I need so that power can be sent over coax feeds
to preamp at the antenna.
I cant find anything on eBay that mentions passing DC in an isolator.
None of the isolators I have will pass DC.
Does anyone know an isolator that passes DC? I would like to avoid
building one.
Chuck
------------------------------
Message: 3
Date: Fri, 3 Dec 2021 13:14:56 -0800
From: Jim Brown
To: topband@contesting.com
Subject: Re: Topband: Ground loop isolator that passes DC
Message-ID:
Content-Type: text/plain; charset=UTF-8; format=flowed
On 12/3/2021 12:32 PM, Chuck Hutton wrote:
> Many years ago I saw some ground loop isolators that pass DC.
There ain't no such thing as a "ground loop." It's a faulty concept,
and
using it to solve a problem are a bad idea. Most problems blamed on
"ground loops" are the result of a failure to follow proper grounding
and bonding practices.
What problem are you trying to solve?
73, Jim K9YC
------------------------------
Message: 4
Date: Fri, 3 Dec 2021 16:21:25 -0500
From: Don Kirk
To: Chuck Hutton
Cc: "topband@contesting.com"
Subject: Re: Topband: Ground loop isolator that passes DC
Message-ID:
Content-Type: text/plain; charset="UTF-8"
Hi Chuck,
Based on the application you mentioned, I suspect you?re looking for
commercially available bias tees. MFJ sells Bias Tees.
Don (wd8dsb)
On Fri, Dec 3, 2021 at 3:33 PM Chuck Hutton wrote:
> Hi -
>
> Many years ago I saw some ground loop isolators that pass DC.
>
> That is exactly what I need so that power can be sent over coax
feeds to
> preamp at the antenna.
>
> I cant find anything on eBay that mentions passing DC in an
isolator.
> None of the isolators I have will pass DC.
>
> Does anyone know an isolator that passes DC? I would like to avoid
> building one.
>
>
> Chuck
>
>
> _________________
> Searchable Archives: http://www.contesting.com/_topband [1] -
Topband
> Reflector
>
------------------------------
Message: 5
Date: Fri, 3 Dec 2021 15:34:32 -0600
From: Richard Thorne
To: topband@contesting.com
Subject: Re: Topband: Ground loop isolator that passes DC
Message-ID:
Content-Type: text/plain; charset=UTF-8; format=flowed
I 'think' what Chuck is trying to do is install? a lightening
protector
at his coax entrance panel.
The problem with lightening protectors is the blocking of DC and you
can't send voltage to the switch, pre-amp or what ever your trying to
power over the coax.
My solution, good or bad, was to install a box outside my shack that
includes a 12v power supply and the bias T.? I inserted the bias-t on
the antenna side of my lightening protectors.? Inside the box I have
an
aluminum plate which is grounded to my system ground.? If I can I'll
post a picture as it shows how items are attached to the aluminum
plate.
Rich - N5ZC
On 12/3/2021 2:32 PM, Chuck Hutton wrote:
> Hi -
>
> Many years ago I saw some ground loop isolators that pass DC.
>
> That is exactly what I need so that power can be sent over coax
feeds to preamp at the antenna.
>
> I cant find anything on eBay that mentions passing DC in an
isolator. None of the isolators I have will pass DC.
>
> Does anyone know an isolator that passes DC? I would like to avoid
building one.
>
>
> Chuck
>
>
> _________________
> Searchable Archives: http://www.contesting.com/_topband [2] -
Topband Reflector
------------------------------
Message: 6
Date: Fri, 3 Dec 2021 14:49:08 -0800
From: Jim Brown
To: topband@contesting.com
Subject: Re: Topband: Ground loop isolator that passes DC
Message-ID:
Content-Type: text/plain; charset=UTF-8; format=flowed
On 12/3/2021 1:34 PM, Richard Thorne wrote:
> The problem with lightening protectors is the blocking of DC and
you
> can't send voltage to the switch, pre-amp or what ever your trying
to
> power over the coax.
There are protectors that don't block DC. A study of mfr catalogs
will
find them.
73, Jim K9YC
------------------------------
Message: 7
Date: Fri, 3 Dec 2021 18:26:25 -0500
From: "John Kaufmann"
To: "'Ignacy Misztal'" ,
Subject: Re: Topband: More radials towards EU
Message-ID:
Content-Type: text/plain; charset="us-ascii"
EZNEC is correct. Adding more radials, even long ones, in a specific
direction won't preferentially favor the direction in which the
radials are
added. It will help raise the overall efficiency of the antenna to a
degree, depending on how many radials are already in place, but any
improvement will be distributed uniformly over all directions.
73, John W1FV
-----Original Message-----
From: Topband
[mailto:topband-bounces+john.kaufmann=verizon.net@contesting.com] On
Behalf
Of Ignacy Misztal
Sent: Friday, December 3, 2021 1:16 PM
To: topband@contesting.com
Subject: Topband: More radials towards EU
My shunt fed tower has 36 radials 70 to 100 ft long. Would adding a
few
longer radials towards EU help to EU?
Eznec says no.
Ignacy NO9E
_________________
Searchable Archives: http://www.contesting.com/_topband [3] - Topband
Reflector
------------------------------
Message: 8
Date: Fri, 3 Dec 2021 23:53:20 -0000
From: "Andrew Ikin"
To: "Chuck Hutton" ,
Subject: Re: Topband: Ground loop isolator that passes DC
Message-ID:
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
Chuck Hutton,
Wrote on Dec. 3.
I guess what Chuck means, is a Ground loop due to the antenna end of
the
coax. screen being connected to Earth thus causing the feeder shield
to
become a loop antenna with the ground RF return path to Rx. Hence,
resulting
in excess noise pick-up.
Normally common mode choke will be of benefit. But I would guess that
Chuck
has already tried this.
One option could be fit a 1:1 isolation transformer at the Rx input
or into
the Bias T. Then use a floating power supply to the drive antenna
pre-amp..
A bias T that already has a common mode choke on the DC input would
help
too.
The Antenna Interfaces manufactures by Wellbrook have this choke
feature.
73
Andrew Ikin G8LUG
------------------------------
Message: 9
Date: Fri, 3 Dec 2021 18:00:13 -0600
From: Frank Krozel
To: Andrew Ikin
Cc: Chuck Hutton , topband@contesting.com
Subject: Re: Topband: Ground loop isolator that passes DC
Message-ID:
Content-Type: text/plain; charset=us-ascii
Are you thinking of a Bias-T?
MFJ sells them with some of their tuners.
-73- Frank KG9H
kg9hfrank@gmail.com
> On Dec 3, 2021, at 5:53 PM, Andrew Ikin wrote:
>
> Chuck Hutton,
>
> Wrote on Dec. 3.
>
> That is exactly what I need so that power can be sent over coax
feeds to
> preamp at the antenna.
> I cant find anything on eBay that mentions passing DC in an
isolator. None
> of the isolators I have will pass DC.
> Does anyone know an isolator that passes DC? I would like to avoid
building
> one.>
>
> I guess what Chuck means, is a Ground loop due to the antenna end
of the coax. screen being connected to Earth thus causing the feeder
shield to become a loop antenna with the ground RF return path to Rx.
Hence, resulting in excess noise pick-up.
> Normally common mode choke will be of benefit. But I would guess
that Chuck has already tried this.
>
> One option could be fit a 1:1 isolation transformer at the Rx input
or into the Bias T. Then use a floating power supply to the drive
antenna pre-amp.. A bias T that already has a common mode choke on the
DC input would help too.
> The Antenna Interfaces manufactures by Wellbrook have this choke
feature.
>
> 73
>
> Andrew Ikin G8LUG
>
> _________________
> Searchable Archives: http://www.contesting.com/_topband [4] -
Topband Reflector
------------------------------
Message: 10
Date: Fri, 3 Dec 2021 16:29:40 -0800
From: Jim Brown
To: topband@contesting.com
Subject: Re: Topband: Ground loop isolator that passes DC
Message-ID:
Content-Type: text/plain; charset=UTF-8; format=flowed
On 12/3/2021 3:53 PM, Andrew Ikin wrote:
> I guess what Chuck means, is a Ground loop due to the antenna end
of the
> coax. screen being connected to Earth thus causing the feeder
shield to
> become a loop antenna with the ground RF return path to Rx. Hence,
> resulting in excess noise pick-up.
A serious common mode choke at the feedpoint is critical for this,
effectively disconnecting the coax shield from the antenna for common
mode current. But proper grounding and bonding in the shack and
throughout the home are critical -- a primary cause of RF in the
shack
is failure to do that.
There are differences with practice in the UK and EU with respect to
connection of earth electrodes. This set of slides shows proper
implementation in North America, which properly considers both power
and antennas with respect to lightning safety. The laws of physics
don't
change at the water's edge. :)
http://k9yc.com/GroundingAndAudio.pdf
/>
73, Jim K9YC
------------------------------
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