Very helpful comments Tom. Mni tnx.
I have a 52 ft INV-L that I cant get any higher. and was thinking
about converting it to a T.
The current L with 26 radials does great in 160 contests, and pretty
good on the valued DX qsos, but have been tempted to convert it to
what I understand to be a much better T antenna option.
Your experience reinforces those thoughts.
Bob.
-----------------------------------------From:
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To: topband@contesting.com
Cc:
Sent: Thursday March 4 2021 12:01:41PM
Subject: Topband Digest, Vol 219, Issue 4
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Today's Topics:
1. Re: G3YRO heard Tues night/Wed morn (W3HKK@roadrunner.com)
2. Re: Wednesday CW DX Activity Night (List Mail)
----------------------------------------------------------------------
Message: 1
Date: Wed, 03 Mar 2021 18:37:02 +0000
From: W3HKK@roadrunner.com
To: "'topband@contesting.com'"
Subject: Re: Topband: G3YRO heard Tues night/Wed morn
Message-ID:
Content-Type: text/plain; charset=UTF-8
around 559 on peaks here in central Ohio. Also heard a central Euro
stations about the same.
Not great but at least making the haul. Will listen again tonight.
Bob
-----------------------------------------From:
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To: topband@contesting.com
Cc:
Sent: Wednesday March 3 2021 12:01:25PM
Subject: Topband Digest, Vol 219, Issue 3
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When replying, please edit your Subject line so it is more specific
than "Re: Contents of Topband digest..."
Today's Topics:
1. Re: Antenna thoughts (Wes)
2. Re: Antenna thoughts (Dave Cuthbert)
3. Re: Antenna thoughts (Richard (Rick) Karlquist)
4. Wednesday CW DX Activity Night (Roger Kennedy)
5. Re: Antenna thoughts (Guy Olinger K2AV)
6. Re: JA on 160m SSB (Han Higasa)
7. Re: JA on 160m SSB (Han Higasa)
----------------------------------------------------------------------
Message: 1
Date: Tue, 2 Mar 2021 12:01:01 -0700
From: Wes
To: topband@contesting.com
Subject: Re: Topband: Antenna thoughts
Message-ID:
Content-Type: text/plain; charset=utf-8; format=flowed
If the direction turns out to be favorable, the "L" actually provides
a bit of
directivity at the expense of filling in the overhead null.
Wes? N7WS
On 3/2/2021 8:28 AM, Thomas Hoyer via Topband wrote:
> I changed my home built Battle Creek Special over to a "tee" for
160 last fall and I feel it performs much better on 160 then the "L"
of the BCS did. Due to yard restrictions the ends of my tee's slope
down a bit, one more then the other. Overall height is approx 52'
with
the tee wires extending out from there. Had to add a bit of base
loading to get a good match.
> TomW3TA
>
>
> -----Original Message-----
> From: GEORGE WALLNER
> To: John ; topband@contesting.com
> Sent: Tue, Mar 2, 2021 9:28 am
> Subject: Re: Topband: Antenna thoughts
>
> John,
> For DX, the T will be better than the L, especially if part of the
L is
> sloping. (Higher radiation resistance.) Also, if the two loading
wires are
> the same length, the antenna will be good on 3.5 and 7 MHz.
Regarding the
> radials, it all depends on how many and how long you have now, but
the T
> will be better for DX, in any case.
>
> 73 and GL,
> George,
>
> On Tue, 2 Mar 2021 02:20:12 -0600
> ? John wrote:
>> Hello all.I currently have a coaxial inv. L.apex at 50ft and rest
going out at abt 45 degrees.The end is abt 20-30 ft high.It has been
a
very good antenna.I used a l because I did not have the option of 2
masts.I am changing a bit.Doing away from vhf/uhf beams.So I have
another 50 ft mast.They are abt 200ft apart.My question is?Would a
tee
type vertical be better that an L.Yes I could elevate 2 or 3
radials.I
am using? a radial ground on the inv.L.Thoughts on this please.I am
not really concerned about matching.Just effenciency.Is a tee better?
Thanks,john
>>
>> Sent from Mail for Windows 10
>>
>>
>> --
>> This email has been checked for viruses by AVG.
>> https://www.avg.com [1] [1]
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------------------------------
Message: 2
Date: Tue, 2 Mar 2021 09:19:58 -1000
From: Dave Cuthbert
To: w5jmw@towerfarm.net
Cc: "topband@contesting.com"
Subject: Re: Topband: Antenna thoughts
Message-ID:
Content-Type: text/plain; charset="UTF-8"
John, here are EZNEC results for your downward sloping inverted-L and
your
T-vertical.
Inverted-L radiation resistance = 8 ohms
T-vertical radiation resistance = 12 ohms
How the radiation efficiency compares depends on your ground system.
The
efficiencies for 2.5, 5, and 10 ohm ground systems are compared:
*Antenna GND R Rad Eff * *T over L*
L 2.5 76%
T 2.5 83% 0.4dB
L 5.0 62%
T 5.0 71% 0.6dB
L 10 44%
T 10 55% 0.9dB
L 20 29%
T 20 38% 1.2dB
Dave KH6AQ
On Mon, Mar 1, 2021 at 10:20 PM John wrote:
> Hello all.I currently have a coaxial inv. L.apex at 50ft and rest
going
> out at abt 45 degrees.The end is abt 20-30 ft high.It has been a
very good
> antenna.I used a l because I did not have the option of 2 masts.I
am
> changing a bit.Doing away from vhf/uhf beams.So I have another 50
ft
> mast.They are abt 200ft apart.My question is?Would a tee type
vertical be
> better that an L.Yes I could elevate 2 or 3 radials.I am using a
radial
> ground on the inv.L.Thoughts on this please.I am not really
concerned about
> matching.Just effenciency.Is a tee better? Thanks,john
>
> Sent from Mail for Windows 10
>
>
>
> --
> This email has been checked for viruses by AVG.
> https://www.avg.com [5] [5]
> _________________
> Searchable Archives: http://www.contesting.com/_topband [6] [6] -
Topband
> Reflector
>
------------------------------
Message: 3
Date: Tue, 2 Mar 2021 13:45:33 -0800
From: "Richard (Rick) Karlquist"
To: Dave Cuthbert , w5jmw@towerfarm.net
Cc: "topband@contesting.com"
Subject: Re: Topband: Antenna thoughts
Message-ID:
Content-Type: text/plain; charset=utf-8; format=flowed
On 3/2/2021 11:19 AM, Dave Cuthbert wrote:
> John, here are EZNEC results for your downward sloping inverted-L
and your
> T-vertical.
>
> Inverted-L radiation resistance = 8 ohms
> T-vertical radiation resistance = 12 ohms
When doing these comparisons on 160 meters, it is crucial
to use the EZNEC "Desc Options" setting (2nd from the bottom
in the main window) to plot vertical and horizontal
radiation separately. Then count only vertical
polarized radiation as the "money spec" (as
we used to say at Agilent :-). If you use combined
polarizations, it is very easy to be fooled into
thinking that an inverted L with a very long top has fantastic
efficiency, vs a T vertical. Well, I will grant you
that it is very efficient at warming the clouds.
73
Rick N6RK
------------------------------
Message: 4
Date: Tue, 2 Mar 2021 23:48:20 -0000
From: "Roger Kennedy"
To:
Subject: Topband: Wednesday CW DX Activity Night
Message-ID:
Content-Type: text/plain; charset="us-ascii"
Well after a few very poor days, it looks like DX Propagation on 160m
has
now improved . . .
So hopefully we'll see some Activity tomorrow night !
73 Roger G3YRO
------------------------------
Message: 5
Date: Tue, 2 Mar 2021 20:30:25 -0500
From: Guy Olinger K2AV
To: Dave Cuthbert
Cc: w5jmw@towerfarm.net, "topband@contesting.com"
Subject: Re: Topband: Antenna thoughts
Message-ID:
Content-Type: text/plain; charset="UTF-8"
I would have to know just exactly how your "Ground R" was constructed
to
comment. The two EZNEC variables for ground description are
dielectric
constant and conductance. Also there is a lot depending on the T
dimensions
and L dimensions in any comparison that would preclude any simple
answer
that depended only on ground characteristics.
Also to really see what is going on, you would need superimposed
patterns
modeled from a property's real dimensions. The radiation resistance
numbers sound like free space or Mininec ground, both with necessary
interpretation work to navigate.
The answers for an L depend enormously on the ratio of vertical to
horizontal, and also independently on the electrical length of the
horizontal as a top load. The simple comparison does not take account
of a
good practice extending the horizontal to approximately 88 feet
regardless
of vertical height, to make sure the vertical wire has the most
integrated
current, all the way up to the bend, regardless of vertical wire
height.
This venture into non-resonance for the sake of performance, reduces
the
difference between a T and an L.
In a comparison of a T and an L, set the T using X vertical feet,
with say
plus and minus 40 feet for the T wires. For a fair fight, the L must
have
the same X vertical wire with an 80 foot horizontal, with the L's
NVIS
angles and the enhancement on the side opposite the horizontal taken
into
account.
An inverted L with 65 feet vertical and 88 feet horizontal, even over
a
commercial grade counterpoise, certainly does not have 8 ohms
radiation resistance. And it is taking advantage of reduced current
in a
counterpoise with ham grade radials.
Beyond that, first off the counterpoise should have been evaluated.
On 160
antennas requiring a counterpoise, the counterpoise efficiency is the
two
ton elephant in the room, with nothing in 2nd place on an awfulness
scale.
Regardless of T and L particulars, even an accurate difference is
heavily
swamped by any inefficiency in the counterpoise. "A few radials on
the
ground" just to get one on the air, can be remarkably lossy.
A peek at the original poster's photos on QRZ, show he was using a
tower
to support the bend in his L. Add to any counterpoise loss the losses
from
a tower supporting a close vertical wire (either T or L). A tower
supporting the bend of an L or the center of a T should be considered
a
secondary winding in a tightly coupled transformer, with the vertical
wire
as the primary, and the tower base connected to universal ground
through a
big resistor
Those two issues can easily nullify the gain of an amplifier. The
total
loss in the two issues smashingly exceeds the difference between T or
L
aerial wire choice by an order of magnitude.
After one has taken care of the elephant in the room, back to the
question
of T or L, the NVIS-defeating high angle hole in a T or pure vertical
is a
real disadvantage for 160 only contests where same continent QSO's
can
dominate the score. With the T you can have huge skips if the band
goes
longish, losing a lot of Qso's. Worse, you can have your run
frequency
taken because the other guy, in a very deep skip zone close to you,
couldn't hear you were there.
The comparison of a given specific T and L is actually a quite
complex
question, and there are no simple answers. One has to assess the
various
loss issues of the specific implementation and surroundings. No
one-size-fits-all answer. Sometimes one has to model every conductor
on the
property, and often because of buried conductors, antenna and
otherwise,
has to do it in EZNEC Pro/NEC4.
And often a huge improvement will have nothing to do with a T vs. L
aerial
wire.
There are ways to minimize tower current when a tower has to be used
to
support the aerial wires, but I've heard none of that discussed here.
73, Guy K2AV
On Tue, Mar 2, 2021 at 2:20 PM Dave Cuthbert wrote:
> John, here are EZNEC results for your downward sloping inverted-L
and your
> T-vertical.
>
> Inverted-L radiation resistance = 8 ohms
> T-vertical radiation resistance = 12 ohms
>
> How the radiation efficiency compares depends on your ground
system. The
> efficiencies for 2.5, 5, and 10 ohm ground systems are compared:
> *Antenna GND R Rad Eff * *T over L*
> L 2.5 76%
> T 2.5 83% 0.4dB
>
> L 5.0 62%
> T 5.0 71% 0.6dB
>
> L 10 44%
> T 10 55% 0.9dB
>
> L 20 29%
> T 20 38% 1.2dB
>
> Dave KH6AQ
>
>
>
> On Mon, Mar 1, 2021 at 10:20 PM John wrote:
>
> > Hello all.I currently have a coaxial inv. L.apex at 50ft and rest
going
> > out at abt 45 degrees.The end is abt 20-30 ft high.It has been a
very
> good
> > antenna.I used a l because I did not have the option of 2 masts.I
am
> > changing a bit.Doing away from vhf/uhf beams.So I have another 50
ft
> > mast.They are abt 200ft apart.My question is?Would a tee type
vertical be
> > better that an L.Yes I could elevate 2 or 3 radials.I am using a
radial
> > ground on the inv.L.Thoughts on this please.I am not really
concerned
> about
> > matching.Just effenciency.Is a tee better? Thanks,john
> >
> > Sent from Mail for Windows 10
> >
> >
> >
> > --
> > This email has been checked for viruses by AVG.
> > https://www.avg.com [7] [7]
> > _________________
> > Searchable Archives: http://www.contesting.com/_topband [8] [8] -
Topband
> > Reflector
> >
> _________________
> Searchable Archives: http://www.contesting.com/_topband [9] [9] -
Topband
> Reflector
>
------------------------------
Message: 6
Date: Wed, 3 Mar 2021 17:07:47 +0900
From: Han Higasa
To: K1ep@arrl.net, topband@contesting.com
Subject: Re: Topband: JA on 160m SSB
Message-ID:
Content-Type: text/plain; charset="UTF-8"
Hi Ed-san
Thank you again for the QSO from KH7M.
FB DX, de Han JE1BMJ
------------------------------
Message: 7
Date: Wed, 3 Mar 2021 17:16:23 +0900
From: Han Higasa
To: ok1cz@ddamtek.cz, topband@contesting.com
Subject: Re: Topband: JA on 160m SSB
Message-ID:
Content-Type: text/plain; charset="UTF-8"
Hi Petr-san
As a link to JA?s band-plan I have written we can use a whole segment
from
1800-1875 for CW from the year 2020.
So, please spread out when operating large CW (or SSB) contests from
now on.
de Han JE1BMJ
> Dear Han,
>
> Thanks for the info on JA band plan. Has there been a change
recently
that allowed JA hams to operate above 1830 kHz CW?
> If JA can operate in the whole segment of 1800 - 1875 kHz CW I
don't
understand why in big contests like CQ WW 160m CW most EU stations
are
squeezed between 1815 and 1830 kHz hoping to work JA.
>
> 73 Petr OK1CZ
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Message: 2
Date: Thu, 4 Mar 2021 10:41:33 +1100
From: List Mail
To: "topband@contesting.com"
Subject: Re: Topband: Wednesday CW DX Activity Night
Message-ID:
Content-Type: text/plain; charset="utf-8"
I came up on air around my sunrise today 2000z and heard E71A, and an
SV9 station (which I need) who was working EU stations that I could
not hear. I went back to bed.
Yesterday evening I worked several stations in USA and JA, but
conditions were really marginal, although I was hitting a couple of US
west coast RBN quite hard.
The tower project is almost complete with about 28 m up. I became
impatient and put a couple of top loading wires on it and a temporary
L-match at the base so I could try it out. The top loaded vertical I
have been working with (22 m high) has been removed as the new tower
was detuning it. The dipole just does not cut it for DX in current
conditions.
I am hoping to work a bit of EU before that opportunity closes late
this month.
73, Luke VK3HJ
Sent from Mail for Windows 10
From: Roger Kennedy
Sent: Wednesday, 3 March 2021 10:48 AM
To: topband@contesting.com
Subject: Topband: Wednesday CW DX Activity Night
Well after a few very poor days, it looks like DX Propagation on 160m
has
now improved . . .
So hopefully we'll see some Activity tomorrow night !
73 Roger G3YRO
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