Hi all - has anyone compared the SAL-30 to the Yankee Clipper 9 circle
array Dave g3rcq
From: "topband-request@contesting.com" <topband-request@contesting.com>
To: topband@contesting.com
Sent: Wednesday, 14 December 2016, 17:00
Subject: Topband Digest, Vol 168, Issue 20
Send Topband mailing list submissions to
topband@contesting.com
To subscribe or unsubscribe via the World Wide Web, visit
http://lists.contesting.com/mailman/listinfo/topband
or, via email, send a message with subject or body 'help' to
topband-request@contesting.com
You can reach the person managing the list at
topband-owner@contesting.com
When replying, please edit your Subject line so it is more specific
than "Re: Contents of Topband digest..."
Today's Topics:
1. Re: Twist a Flag into a Bowtie? (JC)
2. Re: Bowtie Flags (Mark Connelly)
3. Re: Bowtie Flags (Don Kirk)
4. Bowtie Flags ( K1FZ-Bruce )
5. Re: Bowtie Flags (wb6rse1@mac.com)
6. Re: Bowtie Flags (JC)
7. Re: Bowtie Flags (JC)
----------------------------------------------------------------------
Message: 1
Date: Tue, 13 Dec 2016 13:51:55 -0500
From: "JC" <n4is@comcast.net>
To: "'Nick Hall-Patch'" <nhp@ieee.org>
Cc: "'topband'" <topband@contesting.com>
Subject: Re: Topband: Twist a Flag into a Bowtie?
Message-ID: <000001d25571$fa8807d0$ef981770$@comcast.net>
Content-Type: text/plain; charset="us-ascii"
Hi Nick
I would say grounded both ends, don't need to be connected to the antenna
itself, right.
JC
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Nick
Hall-Patch
Sent: Tuesday, December 13, 2016 11:42 AM
To: JC <n4is@comcast.net>
Cc: 'topband' <topband@contesting.com>
Subject: Re: Topband: Twist a Flag into a Bowtie?
So, is the ground wire just left "floating", JC? No electrical
connection to the antenna itself?
Thanks and 73,
Nick
VE7DXR
At 11:23 13-12-16, JC wrote:
>Hi Nick
>
>The wire will reduce loss on the transmission line given a better match
>and phase. In practice you can see change on the SWR and front back. If
>you have a good ground you probably won't see anything changing.
>
>Regards
>JC
>
>-----Original Message-----
>From: Nick Hall-Patch [mailto:nhp@ieee.org]
>Sent: Monday, December 12, 2016 10:59 PM
>To: JC <n4is@comcast.net>
>Cc: 'topband' <topband@contesting.com>
>Subject: Re: Topband: Twist a Flag into a Bowtie?
>
>What kind of improvement in performance is observed by providing a
>better ground, JC? And, where would a ground wire (counterpoise?) be
>connected with the DHDL antenna system?
>
>Thanks and 73,
>
>Nick
>VE7DXR
>
>
>
>At 15:38 11-12-16, JC wrote:
> >Hi Mike and Don
> >
> >The DHDL as well as few other antennas, has a hidden component. The
> >bottom wire parallel to the ground is a transmission line, actually,
> >any antenna parallel to the ground is a transmission line. A
> >beverage antenna a is good example.
> >
> >The ground is the second leg of the transition line, for a K9AY loop
> >it is the same, the bottom wire and the ground form a transmission
> >line. The transmission line allows the Resistor and the Transformer
> >to be moved to the center of the loop. The VE3DO loop is also exactly
> >the
>same.
> >
> >The same way, a DHDL antenna uses the ground to phase the two loops,
> >if you elevate the DHDL high far from the ground, the patter changes.
> >The DHDL is a ground dependent antenna, improving the ground with a
> >ground wire bellow the antenna can fix some ground problems.
> >
> >
> >My two cents.
> >
> >73's
> >JC
> >
> >N4IS
> >
> >-----Original Message-----
> >From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of
> >Don Kirk
> >Sent: Sunday, December 11, 2016 10:13 AM
> >To: D Michael <damichael@verizon.net>
> >Cc: topband <topband@contesting.com>
> >Subject: Re: Topband: Twist a Flag into a Bowtie?
> >
> >Hi Mike,
> >
> >Funny you should ask that.
> >
> >A few months ago (September) I was looking at building a smaller size
> >DHDL using 4Nec2, and there were a few things I saw that I thought
> >needed improvement (I saw things in the full size DHDL that I thought
> >needed improvement, it was not limited to the small size DHDL I was
> >trying to design). Then I started to play around with the location
> >of its termination resistor as well as routing of wires, and wound up
> >with what I called the Terminated Bowtie. I built one in my backyard
> >but my yard is pretty small and the antenna was too close to existing
> >objects (house and chain link
> >fence) and I did not realize the S/N improvement that I expected,
> >nevertheless based on modeling it looks like a winner (9.5 RDF and
> >front to back ratio versus elevation angle very robust).
> >
> >I have attached the preliminary document I put together a few months
> >ago for you and others to view (it might not be perfect, but should
> >convey my design / thoughts). I would love someone to build one of
> >these out in the open to see if the real life build provides results
> >similar to the 4Nec2 modelling I did.
> >
> >Note: Bringing the feedline away from the antenna properly needs to
> >be looked at to minimize distortion of the pattern. As I recall the
> >feedline should not drop down to the ground until it's at least 5
> >feet away from the antenna, and a greater distance would be best.
> >The feedline should also use choke with ground rod similar to what's
> >recommend for other RX antennas we use (beverages, flags, etc.) to
> >block common mode noise from making its way to the antenna feedpoint.
> >
> >Let me know what you think. It might not work, but sure looked good
> >on paper.
> >
> >73,
> >Don (wd8dsb)
> >
> >On Sun, Dec 11, 2016 at 9:41 AM, D Michael <damichael@verizon.net> wrote:
> >
> > >
> > >
> > > I have two flag rx ants and I was looking at the DHDL and DK6ED
> > > Double Loop System V2 and wondering if twisting my Flag rx ants
> > > into Bowties would improve the forward pattern and make them
> > > narrower with better front to back.
> > > I would just ""flip"" the termination resistor end to form a loose
> > > BOWTIE shape.
> > > I have no ant modeling software so I have no way to ponder this
change.
> > > Maybe someone could model doing this.
> > > TNX es 73, Mike W3TS
> > > _________________
> > > Topband Reflector Archives - http://www.contesting.com/_topband
> > >
> >_________________
> >Topband Reflector Archives - http://www.contesting.com/_topband
> >
> >_________________
> >Topband Reflector Archives - http://www.contesting.com/_topband
>
>Nick Hall-Patch
>Victoria, BC
>Canada
Nick Hall-Patch
Victoria, BC
Canada
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
------------------------------
Message: 2
Date: Tue, 13 Dec 2016 14:00:37 -0500
From: Mark Connelly <markwa1ion@aol.com>
To: topband@contesting.com
Subject: Re: Topband: Bowtie Flags
Message-ID: <158f98ed6e6-60f8-e923@webprd-a62.mail.aol.com>
Content-Type: text/plain; charset=utf-8
As Nick undoubtedly knows, Bowtie antennas have been in use by medium wave
broadcast band DXers for some time now.
One I tested here in 2010 is shown in this sketch:
http://www.qsl.net/wa1ion/pictures1/bowtie_s_yarmouth.gif
Some use a dual feedline scheme so the pattern can be reversed. This would be
implemented by 16:1 transformers at each end if 50-75 ohm coaxial cable is used
or 9:1 transformers if using 90-150 ohm balanced feed (CAT-5, speaker wire, two
conductor zip / lamp cord, twisted pair etc.) as recommended by Dallas Lankford
and others. In the balanced feedline case, a 1.8:1 or 2:1 transformer (e.g.
#73 binocular core with 4 turns : 3 turns or 7 turns : 5 turns) is used
in-shack to get to unbalanced coaxial en route to the receiver / transceiver,
RPA-1 or similar amp, or phasing unit.
Dual feedline split flag is another variant:
http://www.qsl.net/wa1ion/pictures1/dual_feed_split_flag.gif
Dual feedline antennas have a 4-pole 2-throw switch at the shack end so either
end can be switched to the receiver path and the opposite end to a 250 or 500
ohm pot that facilitates in-shack null termination adjustment.
Some people go with a single orientation antenna and put a preamp such as the
Wellbrook FLG100LN ( http://www.wellbrook.uk.com/FLG100LN-1 ) right at the
forward side. This tends to overwhelm any feedline pick-up (common-mode or
otherwise) although common-mode choking is still advisable near the antenna
when longer runs (over 60m / 200 ft.) of feedline are involved.
In the case of a single orientation set-up, you then get to figure out what
termination end scheme is best. These basically boil down to the following
options:
(1) Fixed resistor in the 680-1200 ohm range either modelled / guessed-at or
determined by use of a potentiometer if it can somehow be adjusted midway up
the side of the antenna while monitoring a target station to null.
(2) "Vactrol" termination: a photoresistor adjusted by a DC voltage applied on
a control line from the shack: see page 9 of
http://www.durenberger.com/documents/PRESBT2016.pdf
(3) Potentiometer adjusted by a motor drive: see
http://www.bamlog.com/remotepotbox.htm
My experience with the Bowtie I installed in 2010 was that it was about 10-12
dB less sensitive than a Flag or Kaz Delta occupying the same rectangular "box"
of air space.
Nulling off the back could be wider than that of a Flag but the bandwidth at
which the null stayed optimum at a particular terminating resistance was not as
wide as with the Flag (or its SuperLoop base-fed variation:
http://www.bamlog.com/superloop.htm ).
Seeing that the MW broadcast band 530-1710 kHz has a greater max/min frequency
range ratio than the 1800-2000 kHz of 160m, issues that might be problematic
for broadcast DXers could matter a lot less on 160.
Some of the perceived problems of low gain and null bandwidth could easily have
been cured by a combination of rigorous common-mode choking as done on the
Waller Flag ( http://www.kkn.net/dayton2011/N4ISWallerFlag.pdf ) and high gain
at-antenna amplification.
Mark Connelly, WA1ION
South Yarmouth, MA
<<
Nick,?
?
Although I did not measure it, the front to back, and front to side is
better, overall more quiet.
?
It is receiving toward the Caribbean.?
Europe, and USA stations, are lower in signal strength.
?
Can often work?Caribbean and South American stations through a small
pile up when they are not working split.
?
In my case it was a worth while change.
?
The original plan was to be able to drive my car under it.
?
73
Bruce-K1FZ
?
On Mon, 12 Dec 2016 16:35:14 +0000, Nick Hall-Patch wrote:
What specific improvements did you note when the Delta was raised Bruce?
Thanks,
Nick
VE7DXR
>>
------------------------------
Message: 3
Date: Tue, 13 Dec 2016 14:07:33 -0500
From: Don Kirk <wd8dsb@gmail.com>
To: Mark Connelly <markwa1ion@aol.com>
Cc: topband <topband@contesting.com>
Subject: Re: Topband: Bowtie Flags
Message-ID:
<CAKtW65dw+ac0vqyPHGnsrjZ33HHT86o_qupyPstM10HkeBk_1g@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
Hi Mark,
I had no idea a terminated bowtie previously existed, but does not surprise
me.
Thanks for posting.
Don
On Tue, Dec 13, 2016 at 2:00 PM, Mark Connelly via Topband <
topband@contesting.com> wrote:
> As Nick undoubtedly knows, Bowtie antennas have been in use by medium wave
> broadcast band DXers for some time now.
>
> One I tested here in 2010 is shown in this sketch:
> http://www.qsl.net/wa1ion/pictures1/bowtie_s_yarmouth.gif
>
> Some use a dual feedline scheme so the pattern can be reversed. This
> would be implemented by 16:1 transformers at each end if 50-75 ohm coaxial
> cable is used or 9:1 transformers if using 90-150 ohm balanced feed (CAT-5,
> speaker wire, two conductor zip / lamp cord, twisted pair etc.) as
> recommended by Dallas Lankford and others. In the balanced feedline case,
> a 1.8:1 or 2:1 transformer (e.g. #73 binocular core with 4 turns : 3 turns
> or 7 turns : 5 turns) is used in-shack to get to unbalanced coaxial en
> route to the receiver / transceiver, RPA-1 or similar amp, or phasing unit.
>
> Dual feedline split flag is another variant:
> http://www.qsl.net/wa1ion/pictures1/dual_feed_split_flag.gif
>
> Dual feedline antennas have a 4-pole 2-throw switch at the shack end so
> either end can be switched to the receiver path and the opposite end to a
> 250 or 500 ohm pot that facilitates in-shack null termination adjustment.
>
> Some people go with a single orientation antenna and put a preamp such as
> the Wellbrook FLG100LN ( http://www.wellbrook.uk.com/FLG100LN-1 ) right
> at the forward side. This tends to overwhelm any feedline pick-up
> (common-mode or otherwise) although common-mode choking is still advisable
> near the antenna when longer runs (over 60m / 200 ft.) of feedline are
> involved.
>
> In the case of a single orientation set-up, you then get to figure out
> what termination end scheme is best. These basically boil down to the
> following options:
> (1) Fixed resistor in the 680-1200 ohm range either modelled / guessed-at
> or determined by use of a potentiometer if it can somehow be adjusted
> midway up the side of the antenna while monitoring a target station to null.
> (2) "Vactrol" termination: a photoresistor adjusted by a DC voltage
> applied on a control line from the shack: see page 9 of
> http://www.durenberger.com/documents/PRESBT2016.pdf
> (3) Potentiometer adjusted by a motor drive: see http://www.bamlog.com/
> remotepotbox.htm
>
> My experience with the Bowtie I installed in 2010 was that it was about
> 10-12 dB less sensitive than a Flag or Kaz Delta occupying the same
> rectangular "box" of air space.
>
> Nulling off the back could be wider than that of a Flag but the bandwidth
> at which the null stayed optimum at a particular terminating resistance was
> not as wide as with the Flag (or its SuperLoop base-fed variation:
> http://www.bamlog.com/superloop.htm ).
>
> Seeing that the MW broadcast band 530-1710 kHz has a greater max/min
> frequency range ratio than the 1800-2000 kHz of 160m, issues that might be
> problematic for broadcast DXers could matter a lot less on 160.
>
> Some of the perceived problems of low gain and null bandwidth could easily
> have been cured by a combination of rigorous common-mode choking as done on
> the Waller Flag ( http://www.kkn.net/dayton2011/N4ISWallerFlag.pdf ) and
> high gain at-antenna amplification.
>
> Mark Connelly, WA1ION
> South Yarmouth, MA
>
> <<
> Nick,?
>
> ?
> Although I did not measure it, the front to back, and front to side is
> better, overall more quiet.
> ?
> It is receiving toward the Caribbean.?
> Europe, and USA stations, are lower in signal strength.
> ?
> Can often work?Caribbean and South American stations through a small
> pile up when they are not working split.
> ?
> In my case it was a worth while change.
> ?
> The original plan was to be able to drive my car under it.
> ?
> 73
> Bruce-K1FZ
> ?
>
> On Mon, 12 Dec 2016 16:35:14 +0000, Nick Hall-Patch wrote:
>
> What specific improvements did you note when the Delta was raised Bruce?
>
> Thanks,
>
> Nick
> VE7DXR
> >>
> _________________
> Topband Reflector Archives - http://www.contesting.com/_topband
>
------------------------------
Message: 4
Date: Tue, 13 Dec 2016 16:19:11 -0500
From: " K1FZ-Bruce " <k1fz@myfairpoint.net>
To: Mark Connelly <markwa1ion@aol.com>, Topband
<topband@contesting.com>
Subject: Topband: Bowtie Flags
Message-ID: <20161213161911.70ph0raquscwc0s8@webmail.myfairpoint.net>
Content-Type: text/plain; charset=UTF-8; format="flowed"
?
?
Earl, K6SE (sk)? advanced loop antennas on 160 meters. For
information-See Page 34, July 2000 QST magazine.
The small 160 meter bandwidth allows loop optimization.... k6SE gives
dimensions.
?
George Walter AA7JV? helped the TX3A Chesterfield DXpedition group
with interconnected? two half delta loops.
For more information? check "low Band DXing"? 5th edition? page 7-106.
?
Loop antennas optimized for the 160 meter band have been used in
various folded loop? configurations for some time..
?
73
Bruce-k1fz
?
------------------------------
Message: 5
Date: Tue, 13 Dec 2016 14:24:22 -0800
From: wb6rse1@mac.com
To: Top Band List List <topband@contesting.com>
Subject: Re: Topband: Bowtie Flags
Message-ID: <F3A38251-510E-415B-AF36-AC529C52F92F@mac.com>
Content-Type: text/plain; charset=utf-8
Mark?s observation feeds my skepticism of a bowtie vs a flag in the specific
circumstance where a ground independent RX antenna is your only option.
A bowtie would be about half the capture area of an equivalent ?box? flag and
consequently at a immediate disadvantage. If I was going to replace the flag
with another ground independent design in about the same footprint, it would be
a Waller flag.
73 - Steve WB6RSE
On Dec 13, 2016, at 11:00 AM, Mark Connelly via Topband
<topband@contesting.com> wrote:
My experience with the Bowtie I installed in 2010 was that it was about 10-12
dB less sensitive than a Flag or Kaz Delta occupying the same rectangular "box"
of air space.
------------------------------
Message: 6
Date: Tue, 13 Dec 2016 18:27:32 -0500
From: "JC" <n4is@comcast.net>
To: "'Don Kirk'" <wd8dsb@gmail.com>, "'Mark Connelly'"
<markwa1ion@aol.com>
Cc: "'topband'" <topband@contesting.com>
Subject: Re: Topband: Bowtie Flags
Message-ID: <000901d25598$7b9b2200$72d16600$@comcast.net>
Content-Type: text/plain; charset="us-ascii"
Hi Mark
Terminated loops are very old, the first patent belongs to Harold Beverage
Harold Beverage invented wide band receiver antenna, loaded loop in 1941
https://docs.google.com/viewer?url=patentimages.storage.googleapis.com/pdfs/
US2247743.pdf
Most variations of this kind of antennas like this was used by military
during WWII. Some commercial versions started to come up on the 60's, Tom
W8JI worked the first JA using a similar RX antenna with multiple loops
phased end fire.
You see, the loaded loop is a Beverage antenna too.
73
N4IS
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Don Kirk
Sent: Tuesday, December 13, 2016 2:08 PM
To: Mark Connelly <markwa1ion@aol.com>
Cc: topband <topband@contesting.com>
Subject: Re: Topband: Bowtie Flags
Hi Mark,
I had no idea a terminated bowtie previously existed, but does not surprise
me.
Thanks for posting.
Don
On Tue, Dec 13, 2016 at 2:00 PM, Mark Connelly via Topband <
topband@contesting.com> wrote:
> As Nick undoubtedly knows, Bowtie antennas have been in use by medium
> wave broadcast band DXers for some time now.
>
> One I tested here in 2010 is shown in this sketch:
> http://www.qsl.net/wa1ion/pictures1/bowtie_s_yarmouth.gif
>
> Some use a dual feedline scheme so the pattern can be reversed. This
> would be implemented by 16:1 transformers at each end if 50-75 ohm
> coaxial cable is used or 9:1 transformers if using 90-150 ohm balanced
> feed (CAT-5, speaker wire, two conductor zip / lamp cord, twisted pair
> etc.) as recommended by Dallas Lankford and others. In the balanced
> feedline case, a 1.8:1 or 2:1 transformer (e.g. #73 binocular core
> with 4 turns : 3 turns or 7 turns : 5 turns) is used in-shack to get
> to unbalanced coaxial en route to the receiver / transceiver, RPA-1 or
similar amp, or phasing unit.
>
> Dual feedline split flag is another variant:
> http://www.qsl.net/wa1ion/pictures1/dual_feed_split_flag.gif
>
> Dual feedline antennas have a 4-pole 2-throw switch at the shack end
> so either end can be switched to the receiver path and the opposite
> end to a
> 250 or 500 ohm pot that facilitates in-shack null termination adjustment.
>
> Some people go with a single orientation antenna and put a preamp such
> as the Wellbrook FLG100LN ( http://www.wellbrook.uk.com/FLG100LN-1 )
> right at the forward side. This tends to overwhelm any feedline
> pick-up (common-mode or otherwise) although common-mode choking is
> still advisable near the antenna when longer runs (over 60m / 200 ft.)
> of feedline are involved.
>
> In the case of a single orientation set-up, you then get to figure out
> what termination end scheme is best. These basically boil down to the
> following options:
> (1) Fixed resistor in the 680-1200 ohm range either modelled /
> guessed-at or determined by use of a potentiometer if it can somehow
> be adjusted midway up the side of the antenna while monitoring a target
station to null.
> (2) "Vactrol" termination: a photoresistor adjusted by a DC voltage
> applied on a control line from the shack: see page 9 of
> http://www.durenberger.com/documents/PRESBT2016.pdf
> (3) Potentiometer adjusted by a motor drive: see
> http://www.bamlog.com/ remotepotbox.htm
>
> My experience with the Bowtie I installed in 2010 was that it was
> about
> 10-12 dB less sensitive than a Flag or Kaz Delta occupying the same
> rectangular "box" of air space.
>
> Nulling off the back could be wider than that of a Flag but the
> bandwidth at which the null stayed optimum at a particular terminating
> resistance was not as wide as with the Flag (or its SuperLoop base-fed
variation:
> http://www.bamlog.com/superloop.htm ).
>
> Seeing that the MW broadcast band 530-1710 kHz has a greater max/min
> frequency range ratio than the 1800-2000 kHz of 160m, issues that
> might be problematic for broadcast DXers could matter a lot less on 160.
>
> Some of the perceived problems of low gain and null bandwidth could
> easily have been cured by a combination of rigorous common-mode
> choking as done on the Waller Flag (
> http://www.kkn.net/dayton2011/N4ISWallerFlag.pdf ) and high gain
at-antenna amplification.
>
> Mark Connelly, WA1ION
> South Yarmouth, MA
>
> <<
> Nick,?
>
> ?
> Although I did not measure it, the front to back, and front to side is
> better, overall more quiet.
> ?
> It is receiving toward the Caribbean.?
> Europe, and USA stations, are lower in signal strength.
> ?
> Can often work?Caribbean and South American stations through a small
> pile up when they are not working split.
> ?
> In my case it was a worth while change.
> ?
> The original plan was to be able to drive my car under it.
> ?
> 73
> Bruce-K1FZ
> ?
>
> On Mon, 12 Dec 2016 16:35:14 +0000, Nick Hall-Patch wrote:
>
> What specific improvements did you note when the Delta was raised Bruce?
>
> Thanks,
>
> Nick
> VE7DXR
> >>
> _________________
> Topband Reflector Archives - http://www.contesting.com/_topband
>
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
------------------------------
Message: 7
Date: Tue, 13 Dec 2016 18:36:58 -0500
From: "JC" <n4is@comcast.net>
To: "'Don Kirk'" <wd8dsb@gmail.com>, "'Mark Connelly'"
<markwa1ion@aol.com>
Cc: "'topband'" <topband@contesting.com>
Subject: Re: Topband: Bowtie Flags
Message-ID: <000a01d25599$cc7d32c0$65779840$@comcast.net>
Content-Type: text/plain; charset="us-ascii"
Sorry, the invention was in 1938 and the patent issued 1941
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of JC
Sent: Tuesday, December 13, 2016 6:28 PM
To: 'Don Kirk' <wd8dsb@gmail.com>; 'Mark Connelly' <markwa1ion@aol.com>
Cc: 'topband' <topband@contesting.com>
Subject: Re: Topband: Bowtie Flags
Hi Mark
Terminated loops are very old, the first patent belongs to Harold Beverage
Harold Beverage invented wide band receiver antenna, loaded loop in 1941
https://docs.google.com/viewer?url=patentimages.storage.googleapis.com/pdfs/
US2247743.pdf
Most variations of this kind of antennas like this was used by military
during WWII. Some commercial versions started to come up on the 60's, Tom
W8JI worked the first JA using a similar RX antenna with multiple loops
phased end fire.
You see, the loaded loop is a Beverage antenna too.
73
N4IS
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Don Kirk
Sent: Tuesday, December 13, 2016 2:08 PM
To: Mark Connelly <markwa1ion@aol.com>
Cc: topband <topband@contesting.com>
Subject: Re: Topband: Bowtie Flags
Hi Mark,
I had no idea a terminated bowtie previously existed, but does not surprise
me.
Thanks for posting.
Don
On Tue, Dec 13, 2016 at 2:00 PM, Mark Connelly via Topband <
topband@contesting.com> wrote:
> As Nick undoubtedly knows, Bowtie antennas have been in use by medium
> wave broadcast band DXers for some time now.
>
> One I tested here in 2010 is shown in this sketch:
> http://www.qsl.net/wa1ion/pictures1/bowtie_s_yarmouth.gif
>
> Some use a dual feedline scheme so the pattern can be reversed. This
> would be implemented by 16:1 transformers at each end if 50-75 ohm
> coaxial cable is used or 9:1 transformers if using 90-150 ohm balanced
> feed (CAT-5, speaker wire, two conductor zip / lamp cord, twisted pair
> etc.) as recommended by Dallas Lankford and others. In the balanced
> feedline case, a 1.8:1 or 2:1 transformer (e.g. #73 binocular core
> with 4 turns : 3 turns or 7 turns : 5 turns) is used in-shack to get
> to unbalanced coaxial en route to the receiver / transceiver, RPA-1 or
similar amp, or phasing unit.
>
> Dual feedline split flag is another variant:
> http://www.qsl.net/wa1ion/pictures1/dual_feed_split_flag.gif
>
> Dual feedline antennas have a 4-pole 2-throw switch at the shack end
> so either end can be switched to the receiver path and the opposite
> end to a
> 250 or 500 ohm pot that facilitates in-shack null termination adjustment.
>
> Some people go with a single orientation antenna and put a preamp such
> as the Wellbrook FLG100LN ( http://www.wellbrook.uk.com/FLG100LN-1 )
> right at the forward side. This tends to overwhelm any feedline
> pick-up (common-mode or otherwise) although common-mode choking is
> still advisable near the antenna when longer runs (over 60m / 200 ft.)
> of feedline are involved.
>
> In the case of a single orientation set-up, you then get to figure out
> what termination end scheme is best. These basically boil down to the
> following options:
> (1) Fixed resistor in the 680-1200 ohm range either modelled /
> guessed-at or determined by use of a potentiometer if it can somehow
> be adjusted midway up the side of the antenna while monitoring a
> target
station to null.
> (2) "Vactrol" termination: a photoresistor adjusted by a DC voltage
> applied on a control line from the shack: see page 9 of
> http://www.durenberger.com/documents/PRESBT2016.pdf
> (3) Potentiometer adjusted by a motor drive: see
> http://www.bamlog.com/ remotepotbox.htm
>
> My experience with the Bowtie I installed in 2010 was that it was
> about
> 10-12 dB less sensitive than a Flag or Kaz Delta occupying the same
> rectangular "box" of air space.
>
> Nulling off the back could be wider than that of a Flag but the
> bandwidth at which the null stayed optimum at a particular terminating
> resistance was not as wide as with the Flag (or its SuperLoop base-fed
variation:
> http://www.bamlog.com/superloop.htm ).
>
> Seeing that the MW broadcast band 530-1710 kHz has a greater max/min
> frequency range ratio than the 1800-2000 kHz of 160m, issues that
> might be problematic for broadcast DXers could matter a lot less on 160.
>
> Some of the perceived problems of low gain and null bandwidth could
> easily have been cured by a combination of rigorous common-mode
> choking as done on the Waller Flag (
> http://www.kkn.net/dayton2011/N4ISWallerFlag.pdf ) and high gain
at-antenna amplification.
>
> Mark Connelly, WA1ION
> South Yarmouth, MA
>
> <<
> Nick,?
>
> ?
> Although I did not measure it, the front to back, and front to side is
> better, overall more quiet.
> ?
> It is receiving toward the Caribbean.?
> Europe, and USA stations, are lower in signal strength.
> ?
> Can often work?Caribbean and South American stations through a small
> pile up when they are not working split.
> ?
> In my case it was a worth while change.
> ?
> The original plan was to be able to drive my car under it.
> ?
> 73
> Bruce-K1FZ
> ?
>
> On Mon, 12 Dec 2016 16:35:14 +0000, Nick Hall-Patch wrote:
>
> What specific improvements did you note when the Delta was raised Bruce?
>
> Thanks,
>
> Nick
> VE7DXR
> >>
> _________________
> Topband Reflector Archives - http://www.contesting.com/_topband
>
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
------------------------------
Subject: Digest Footer
_______________________________________________
Topband mailing list
Topband@contesting.com
http://lists.contesting.com/mailman/listinfo/topband
------------------------------
End of Topband Digest, Vol 168, Issue 20
****************************************
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
|
