Topband: Topband Digest, Vol 217, Issue 5
Sam Josuweit
samjos at epix.net
Sun Jan 3 17:48:52 EST 2021
Hi Bob,
I'm currently running 4 Bogs with a switching system. The lengths are
220-250 feet, and I believe the optimal length really depends on your
ground. With 700 feet of good quality coax RG6/RG11 and good transformers,
the preamp in my rig is enough, but a preamp in field would not hurt. They
are quiet and directional. I use them because my land is shaped like a long
rectangle and in some directions I don't have enough room for a full length
beverage. They are almost invisible, which makes the XYL happy. I take them
down in the summer so I can mow the fields. They do not work as well as a
normal full sized beverage, but they do work. Do some searching on youtube
and you will see some A/B comparisons that are helpful.
Sam(N3XZ)
-----Original Message-----
From: Topband [mailto:topband-bounces+samjos=epix.net at contesting.com] On
Behalf Of W3HKK at roadrunner.com
Sent: Sunday, January 03, 2021 3:01 PM
To: 'topband at contesting.com'
Subject: Re: Topband: Topband Digest, Vol 217, Issue 5
anyone with experience using a 300' BOG? Suggestions based on your
experience?
ie are they worth it?
I tried one before but without a preamp and found it worthless. (
almost no signals heard)
suggestions on best preamps? With all in good working order, what
benefits do they provide? Comparable to a longer Beverage?
Tnx
Bob
-----------------------------------------From:
topband-request at contesting.com
To: topband at contesting.com
Cc:
Sent: Sunday January 3 2021 11:59:27AM
Subject: Topband Digest, Vol 217, Issue 5
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Today's Topics:
1. Influence of ground water level on vertical performance.
(Henk Remijn PA5KT)
2. Need Ideas For "Fusing" Beverages From Falling Trees (Randy)
3. Re: (2wire) Beverage transformers (HA3LN)
4. Re: (2wire) Beverage transformers (HA3LN)
5. Re: (2wire) Beverage transformers (HA3LN)
6. Re: (2wire) Beverage transformers (HA3LN)
7. Re: Need Ideas For "Fusing" Beverages From Falling Trees
(Glenn kd0q)
8. Re: Need Ideas For "Fusing" Beverages From Falling Trees
(MU 4CX250B)
9. Re: Need Ideas For "Fusing" Beverages From Falling Trees
(VE6WZ_Steve)
10. Need Ideas For "Fusing" Beverages From Falling Trees
(Roger Parsons)
11. Re: Need Ideas For "Fusing" Beverages From Falling Trees
(Mark Robinson)
12. Re: Need Ideas For "Fusing" Beverages From Falling Trees
(Mark - N5OT)
13. Re: Need Ideas For "Fusing" Beverages From Falling Trees
(CUTTER DAVID)
----------------------------------------------------------------------
Message: 1
Date: Sun, 3 Jan 2021 11:03:14 +0100
From: Henk Remijn PA5KT
To: topband at contesting.com
Subject: Topband: Influence of ground water level on vertical
performance.
Message-ID:
Content-Type: text/plain; charset=utf-8; format=flowed
Hi,
I am searching for info about influence of ground water level on
vertical performance.
Any info or references to articles is welcome.
73 Henk PA5KT
------------------------------
Message: 2
Date: Sun, 3 Jan 2021 11:54:30 +0000 (UTC)
From: Randy
To: topband at contesting.com
Subject: Topband: Need Ideas For "Fusing" Beverages From Falling
Trees
Message-ID:
Content-Type: text/plain; charset=UTF-8
I have several 600 foot beverages made of WD-1A mil wire that run
through heavy woods.? They can handle the random falling branch but
when a large tree falls over them they break.? The wire is held in
place with electric fence plastic insulators that are nailed to trees
every 100 feet.?I would like to add a smaller diameter wire to each
insulator to act as a "fuse" when a tree falls across them.? I am
looking for ideas as to the best way to do this.? Maybe a number 26
wire?? The wire size has to be heavy enough to support the wire in
normal use but weak enough to break when hit by a
tree.?Suggestions??73?Randy W9ZR
------------------------------
Message: 3
Date: Sun, 3 Jan 2021 14:52:11 +0100
From: HA3LN
To: Don Kirk , Lee STRAHAN
Cc: Mike Waters , topband
Subject: Re: Topband: (2wire) Beverage transformers
Message-ID:
Content-Type: text/plain; charset=utf-8; format=flowed
Hi All,
Yes, I refer to this 2-wire design:
http://ha3ln.hu/2wire.jpg
/>
73!
Csaba
On 2021-01-02 22:53, Don Kirk wrote:
> Hi Lee,
>
> Csaba also refers to this transformer as T2 and based on what he
has said
> so far I suspect he is constructing something similar to the two
direction
> beverage shown in figure 7-115 in the 5th edition of Low-Band
DXing. And
> T2 is indeed a two winding transformer with center tap. This
transformer
> transforms the impedance of the open wire transmission line (745
ohms in
> Csabas case) to the coaxial feedline (75 or 50 ohm). The center tap
is
> used to feed another transformer (T1).
>
> I could be wrong but reading between the lines I probably am
correct.
>
> Just FYI,
> Don (wd8dsb)
>
> On Sat, Jan 2, 2021 at 4:09 PM Don Kirk wrote:
>
>> Hi Lee,
>>
>> Csaba said his transformer was " n1=3T/n2=12T tapped @6T ". This
sure
>> sounds like a transformer with two separate windings (3 Turns on
the
>> Primary, and 12 Turns on the Secondary and then it also has a
center tap on
>> the secondary), but I could be wrong. I think Csaba needs to
clarify
>> exactly what his transformer is, and his test circuit.
>>
>> Don (wd8dsb)
>>
>> On Sat, Jan 2, 2021 at 3:22 PM Lee STRAHAN wrote:
>>
>>> Hi Mike,
>>> Assuming that you did not miss that this was a tapped winding and
not
>>> separate windings as Csaba mentioned. I see on reflection that he
measured
>>> 1:1.16 on one of his tests. In reality it wont likely get much
better than
>>> that. That test was likely the 3:12 he mentioned using. The high
impedance
>>> side of these transformers are a little unpredictable using
simple formulas
>>> with winding capacitance and magnetizing inductance added in the
mix.
>>> Sometimes I use wire wrap wire if it is not going to be used
outside
>>> otherwise I use #27 high temp motor winding class insulation wire
which
>>> helps keep from shorting the wires to the core. I have the
benefit of many
>>> part spools of motor winding wire scraps from a best friend and
Ham in the
>>> Motor rewinding business. By the way, Norton amplifiers require
1:11:4
>>> which is the same problem to solve as they are separate windings
in the
>>> ones I use. I also fit shrink tubing in the Norton amp cores for
insulation
>>> first. I don?t use Teflon because it has a dielectric constant
around 5
>>> which increases the capacitance from the wire to the core. Its
tedious but
>>> can be done easily. And in the case of the Norton amp it leaves
room for a
>>> larger wire on the 1 turn winding. Yes 4 AND16 for 20 total can
be done but
>>> yes it takes time and lots of patience. For those turns counts I
go to # 75
>>> material toroid cores which have slightly more winding room but
require
>>> more turns usually for 160 meter stuff. All this probably more
than you
>>> wanted to know. HNY
>>> Lee K7TJR OR
>>>
>>> From: Mike Waters
>>> Sent: Saturday, January 2, 2021 11:44 AM
>>> To: Lee K7TJR
>>> Cc: HA3LN ; topband
>>> Subject: Re: Topband: (2wire) Beverage transformers
>>>
>>> Lee,
>>>
>>> What kind of wire do you use that allows that many turns (4t and
16t)?
>>>
>>> 73 Mike
>>> W0BTU
>>>
>>> On Sat, Jan 2, 2021, 1:37 PM Lee STRAHAN > k7tjr at msn.com>> wrote:
>>> Hello Csaba,
>>> I approach this problem this way your impedance ratio is 745/50
ohms
>>> or 14.9 . To get turns ratio use the square root of that which is
3.86 . So
>>> round that up to 4 as a good turns ratio.
>>> On a BN73-202 core I usually use a minimum of 4 turns on the 50
ohm
>>> side for 160 meters, so the secondary would need 4 turns ratio
times that
>>> for 16 turns. Therefore 16 turns tapped at 4 turns should work
for you.
>>> Some will say the 3 turns on the 50 ohm side should work and the
secondary
>>> then would be turns ratio 4 times that or 12 turns. Therefore 12
turns
>>> tapped at 3 turns should work well also. Sorry, I do not follow
your
>>> formula as shown but you can use the above and it will work fine
as an 800
>>> ohm load to the 745 ohm source. This will reflect 745/16 or 46.6
ohms to
>>> your cable. SWR for that at the 50 ohm cable is 50/46.6 or 1.07
using
>>> resistance only for evaluation.
>>> Lee K7TJR OR
>>>
>>> -----Original Message-----
>>> From: Topband > msn.com at contesting.com>> On Behalf Of HA3LN
>>> Sent: Saturday, January 2, 2021 4:59 AM
>>> To: topband at contesting.com
>>> Subject: Topband: (2wire) Beverage transformers
>>>
>>> Hi All and HNY for 2021.
>>>
>>> Preparing for the CQ160m with new (2 coax) 2-wire beverages to
cover the
>>> missing azimuthal gaps based on LBDX. The first 2x Bevs worked
great back
>>> in last Jan.
>>>
>>> Now I have difficulties with reaching good imped match with the
>>> T2 transformer (responsible to transform the 745 Ohms wire
impedance to
>>> 50 Ohm coax). I use n1=3T/n2=12T tapped @6T transformer (2m high,
20cm wide
>>> with 0.8mm wire)
>>>
>>> What can be the reason for the impedance transformation is rather
off to
>>> the calculated value?
>>>
>>> This is the T2 transformer from 2019:
>>> http://ha3ln.hu/VNA_190116_230811.jpg
/> >>> ...and this from yesterday:
>>> http://ha3ln.hu/VNA_210101_153241.jpg
/> >>>
>>> I have
>>> - same wire with the diam (even from the same roll)
>>> - same BN73-202 cores (tried to use several cores from different
>>> sources to eliminate the possible mix inconsistencies)
>>> - same winding method (including n2 tapping)
>>> - created a low inductance test resistor network for 744 Ohms
>>>
>>> ...tried to wind
>>> - lousy, and precise (crossing windings vs. side-by-side, bunched
>>> wires, etc.)
>>> - n1 first and n2, after n2 first and n1, of course no
difference.
>>> - without the tapping, same as above.
>>> - difference turning ratios (3/12, 2/12, 1/12, 3/11, etc.) to see
>>> the change
>>>
>>>
>>> The best I could reach now on 160m is
>>> - SWR: 1:1.29 (Rs=40.4 Ohms, Xs=-5.4 Ohms) vs. in 2019:
>>> - SWR: 1:1.16 (Rs=43.2 Ohms, Xs=-1.6 Ohms)
>>>
>>> I know, Beverages are really die hard antennas and this increased
>>> mismatch might have zero effect on performance but still, the
engineer part
>>> of me...
>>>
>>> _________________
>>> Searchable Archives: http://www.contesting.com/_topband [1] -
Topband
>>> Reflector
>>>
>>
>
------------------------------
Message: 4
Date: Sun, 3 Jan 2021 15:44:42 +0100
From: HA3LN
To: topband at contesting.com
Subject: Re: Topband: (2wire) Beverage transformers
Message-ID:
Content-Type: text/plain; charset=utf-8; format=flowed
Hi Lee,
Thanks for the notes.
Yes, the 1:1.16 measurement was from 2019 which I take as baseline.
My aim was to have similar transformers for the new 2-wire directions
but somehow I cannot wind them better than 1:1.29.
I agree with Dave this is not something I could even observe on the
air.
As all the materials are exactly the same as last time I was
interested
if someone has experience on the reasoning.
But I will use this versions.
Thanks and 73!
Csaba
On 2021-01-02 23:15, Lee STRAHAN wrote:
> Hi Don,
> Regardless of the transformer whether it?s a tapped or separate. I
gave him the tools that should make whatever he does correct.
Personally I keep my Beverage when I make one at 450 ohms which makes
the matching much easier for me. I just put up my first one yesterday
in several years to test a new brainstorm antenna.
> From what I saw he had a 1:1.16 SWR which could not get much better
in my opinion. Apparently he thought it could be better.
> All is good HNY
> Lee K7TJR OR
>
>
> From: Don Kirk
> Sent: Saturday, January 2, 2021 1:54 PM
> To: Lee STRAHAN
> Cc: HA3LN ; Mike Waters ; topband
> Subject: Re: Topband: (2wire) Beverage transformers
>
> Hi Lee,
>
> Csaba also refers to this transformer as T2 and based on what he
has said so far I suspect he is constructing something similar to the
two direction beverage shown in figure 7-115 in the 5th edition of
Low-Band DXing. And T2 is indeed a two winding transformer with center
tap. This transformer transforms the impedance of the open wire
transmission line (745 ohms in Csabas case) to the coaxial feedline
(75 or 50 ohm). The center tap is used to feed another transformer
(T1).
>
> I could be wrong but reading between the lines I probably am
correct.
>
> Just FYI,
> Don (wd8dsb)
>
> On Sat, Jan 2, 2021 at 4:09 PM Don Kirk wrote:
> Hi Lee,
>
> Csaba said his transformer was " n1=3T/n2=12T tapped @6T ". This
sure sounds like a transformer with two separate windings (3 Turns on
the Primary, and 12 Turns on the Secondary and then it also has a
center tap on the secondary), but I could be wrong. I think Csaba
needs to clarify exactly what his transformer is, and his test
circuit.
>
> Don (wd8dsb)
>
> On Sat, Jan 2, 2021 at 3:22 PM Lee STRAHAN wrote:
> Hi Mike,
> Assuming that you did not miss that this was a tapped winding and
not separate windings as Csaba mentioned. I see on reflection that he
measured 1:1.16 on one of his tests. In reality it wont likely get
much better than that. That test was likely the 3:12 he mentioned
using. The high impedance side of these transformers are a little
unpredictable using simple formulas with winding capacitance and
magnetizing inductance added in the mix.
> Sometimes I use wire wrap wire if it is not going to be used
outside otherwise I use #27 high temp motor winding class insulation
wire which helps keep from shorting the wires to the core. I have the
benefit of many part spools of motor winding wire scraps from a best
friend and Ham in the Motor rewinding business. By the way, Norton
amplifiers require 1:11:4 which is the same problem to solve as they
are separate windings in the ones I use. I also fit shrink tubing in
the Norton amp cores for insulation first. I don?t use Teflon because
it has a dielectric constant around 5 which increases the capacitance
from the wire to the core. Its tedious but can be done easily. And in
the case of the Norton amp it leaves room for a larger wire on the 1
turn winding. Yes 4 AND16 for 20 total can be done but yes it takes
time and lots of patience. For those turns counts I go to # 75
material toroid cores which have slightly more winding room but
require more turns usually for 160 meter stuf
f. All this probably more than you wanted to know. HNY
> Lee K7TJR OR
>
> From: Mike Waters
> Sent: Saturday, January 2, 2021 11:44 AM
> To: Lee K7TJR
> Cc: HA3LN ; topband
> Subject: Re: Topband: (2wire) Beverage transformers
>
> Lee,
>
> What kind of wire do you use that allows that many turns (4t and
16t)?
>
> 73 Mike
> W0BTU
>
> On Sat, Jan 2, 2021, 1:37 PM Lee STRAHAN wrote:
> Hello Csaba,
> I approach this problem this way your impedance ratio is 745/50
ohms or 14.9 . To get turns ratio use the square root of that which is
3.86 . So round that up to 4 as a good turns ratio.
> On a BN73-202 core I usually use a minimum of 4 turns on the 50 ohm
side for 160 meters, so the secondary would need 4 turns ratio times
that for 16 turns. Therefore 16 turns tapped at 4 turns should work
for you. Some will say the 3 turns on the 50 ohm side should work and
the secondary then would be turns ratio 4 times that or 12 turns.
Therefore 12 turns tapped at 3 turns should work well also. Sorry, I
do not follow your formula as shown but you can use the above and it
will work fine as an 800 ohm load to the 745 ohm source. This will
reflect 745/16 or 46.6 ohms to your cable. SWR for that at the 50 ohm
cable is 50/46.6 or 1.07 using resistance only for evaluation.
> Lee K7TJR OR
>
> -----Original Message-----
> From: Topband On Behalf Of HA3LN
> Sent: Saturday, January 2, 2021 4:59 AM
> To: topband at contesting.com
> Subject: Topband: (2wire) Beverage transformers
>
> Hi All and HNY for 2021.
>
> Preparing for the CQ160m with new (2 coax) 2-wire beverages to
cover the missing azimuthal gaps based on LBDX. The first 2x Bevs
worked great back in last Jan.
>
> Now I have difficulties with reaching good imped match with the
> T2 transformer (responsible to transform the 745 Ohms wire
impedance to 50 Ohm coax). I use n1=3T/n2=12T tapped @6T transformer
(2m high, 20cm wide with 0.8mm wire)
>
> What can be the reason for the impedance transformation is rather
off to the calculated value?
>
> This is the T2 transformer from 2019:
> http://ha3ln.hu/VNA_190116_230811.jpg
/> > ...and this from yesterday:
> http://ha3ln.hu/VNA_210101_153241.jpg
/> >
> I have
> - same wire with the diam (even from the same roll)
> - same BN73-202 cores (tried to use several cores from different
> sources to eliminate the possible mix inconsistencies)
> - same winding method (including n2 tapping)
> - created a low inductance test resistor network for 744 Ohms
>
> ...tried to wind
> - lousy, and precise (crossing windings vs. side-by-side, bunched
> wires, etc.)
> - n1 first and n2, after n2 first and n1, of course no difference.
> - without the tapping, same as above.
> - difference turning ratios (3/12, 2/12, 1/12, 3/11, etc.) to see
> the change
>
>
> The best I could reach now on 160m is
> - SWR: 1:1.29 (Rs=40.4 Ohms, Xs=-5.4 Ohms) vs. in 2019:
> - SWR: 1:1.16 (Rs=43.2 Ohms, Xs=-1.6 Ohms)
>
> I know, Beverages are really die hard antennas and this increased
mismatch might have zero effect on performance but still, the engineer
part of me...
>
> _________________
> Searchable Archives: http://www.contesting.com/_topband [2] -
Topband Reflector
> _________________
> Searchable Archives: http://www.contesting.com/_topband [3] -
Topband Reflector
>
------------------------------
Message: 5
Date: Sun, 3 Jan 2021 15:45:16 +0100
From: HA3LN
To: topband at contesting.com
Subject: Re: Topband: (2wire) Beverage transformers
Message-ID:
Content-Type: text/plain; charset=utf-8; format=flowed
...no problem Lee, actually each new idea helps.
I'll give a try the n1=4T version with a 0.3mm (~AWG 28/29) wire to
see
if I can push a bit better matching.
Sorry for the links I tried to avoid sending fairly large pics to the
list directly.
I have the same measurement setup as Don's sent yesterday, the
loading
resistors are similar too, soldered them from 2W metal oxide pieces,
resulting 744 Ohms, which is within 1 Ohm to the open wire calculated
value.
What I see comparing the "old" transformer and the new ones that it
has
less linearity and as Don said it has significantly worse Z(s).
@7MHz.
It might suggests that the core has different mix which gave the
higher
results. I wound as least 15 transformers with ~10 different BN73-202
cores from different sources to avoid similar manufacturing batches
but
I could not see improvements, so I concluded this as core independent
reason.
http://ha3ln.hu/old_new.jpg
/> (green=2020 version, white=2019 transformer version)
Interesting that the SWR curve minimum inflection point is roughly
halved, which was @850KHz, it is @400KHz in 2021.
Tried Don's advise to twist the prim/sec ends of both n1 and n2.
Interestingly enough if I twisted the one made from 0.3mm wire, I
could
reach the 1:1.16 measurement values again, but if I did the same to
one
made from 0.5mm diam wire it became worse.
73!
Csaba
On 2021-01-03 1:06, Lee STRAHAN wrote:
> Sorry Guys, I miss interpreted Csaba?s transformer problem. My
email program truncated the URL?s and most of the information past
that point. What I did get I misread as a result so now I am curious
also of his dilemma.
> Lee K7TJR OR
>
> From: Don Kirk
> Sent: Saturday, January 2, 2021 3:03 PM
> To: Lee STRAHAN
> Cc: HA3LN ; Mike Waters
> Subject: Re: Topband: (2wire) Beverage transformers
>
> Hi Lee,
>
> I don?t think he needed any tools (formulas, etc.), he is just
trying to figure out why his recently made transformer does match
closer to one he made a year ago. He too agrees that the SWR with his
new transformer is likely not an issue, he is just trying to figure
out why his new transformer is different than his previous one, and
that?s why I measured one of my own so he had another data point to
work with.
>
> His transformer from a year ago was 1.16 to 1 whereas his new
transformer measured 1.29 to 1 and that?s bugging him from an
obsessive standpoint.
>
> The reason I mentioned 2 windings was because of how you responded
to Mikes question. I'm really not familiar with reversible beverages
and jumping into this topic helped me learn a bit about them (I love
learning).
>
> Just FYI, and Happy New Year to you and yours too.
> Don (wd8dsb)
>
>
>
> On Sat, Jan 2, 2021 at 5:15 PM Lee STRAHAN wrote:
> Hi Don,
> Regardless of the transformer whether it?s a tapped or separate. I
gave him the tools that should make whatever he does correct.
Personally I keep my Beverage when I make one at 450 ohms which makes
the matching much easier for me. I just put up my first one yesterday
in several years to test a new brainstorm antenna.
> From what I saw he had a 1:1.16 SWR which could not get much better
in my opinion. Apparently he thought it could be better.
> All is good HNY
> Lee K7TJR OR
>
>
> From: Don Kirk
> Sent: Saturday, January 2, 2021 1:54 PM
> To: Lee STRAHAN
> Cc: HA3LN ; Mike Waters ; topband
> Subject: Re: Topband: (2wire) Beverage transformers
>
> Hi Lee,
>
> Csaba also refers to this transformer as T2 and based on what he
has said so far I suspect he is constructing something similar to the
two direction beverage shown in figure 7-115 in the 5th edition of
Low-Band DXing. And T2 is indeed a two winding transformer with center
tap. This transformer transforms the impedance of the open wire
transmission line (745 ohms in Csabas case) to the coaxial feedline
(75 or 50 ohm). The center tap is used to feed another transformer
(T1).
>
> I could be wrong but reading between the lines I probably am
correct.
>
> Just FYI,
> Don (wd8dsb)
>
> On Sat, Jan 2, 2021 at 4:09 PM Don Kirk wrote:
> Hi Lee,
>
> Csaba said his transformer was " n1=3T/n2=12T tapped @6T ". This
sure sounds like a transformer with two separate windings (3 Turns on
the Primary, and 12 Turns on the Secondary and then it also has a
center tap on the secondary), but I could be wrong. I think Csaba
needs to clarify exactly what his transformer is, and his test
circuit.
>
> Don (wd8dsb)
>
> On Sat, Jan 2, 2021 at 3:22 PM Lee STRAHAN wrote:
> Hi Mike,
> Assuming that you did not miss that this was a tapped winding and
not separate windings as Csaba mentioned. I see on reflection that he
measured 1:1.16 on one of his tests. In reality it wont likely get
much better than that. That test was likely the 3:12 he mentioned
using. The high impedance side of these transformers are a little
unpredictable using simple formulas with winding capacitance and
magnetizing inductance added in the mix.
> Sometimes I use wire wrap wire if it is not going to be used
outside otherwise I use #27 high temp motor winding class insulation
wire which helps keep from shorting the wires to the core. I have the
benefit of many part spools of motor winding wire scraps from a best
friend and Ham in the Motor rewinding business. By the way, Norton
amplifiers require 1:11:4 which is the same problem to solve as they
are separate windings in the ones I use. I also fit shrink tubing in
the Norton amp cores for insulation first. I don?t use Teflon because
it has a dielectric constant around 5 which increases the capacitance
from the wire to the core. Its tedious but can be done easily. And in
the case of the Norton amp it leaves room for a larger wire on the 1
turn winding. Yes 4 AND16 for 20 total can be done but yes it takes
time and lots of patience. For those turns counts I go to # 75
material toroid cores which have slightly more winding room but
require more turns usually for 160 meter stuf
f. All this probably more than you wanted to know. HNY
> Lee K7TJR OR
>
> From: Mike Waters
> Sent: Saturday, January 2, 2021 11:44 AM
> To: Lee K7TJR
> Cc: HA3LN ; topband
> Subject: Re: Topband: (2wire) Beverage transformers
>
> Lee,
>
> What kind of wire do you use that allows that many turns (4t and
16t)?
>
> 73 Mike
> W0BTU
>
> On Sat, Jan 2, 2021, 1:37 PM Lee STRAHAN wrote:
> Hello Csaba,
> I approach this problem this way your impedance ratio is 745/50
ohms or 14.9 . To get turns ratio use the square root of that which is
3.86 . So round that up to 4 as a good turns ratio.
> On a BN73-202 core I usually use a minimum of 4 turns on the 50 ohm
side for 160 meters, so the secondary would need 4 turns ratio times
that for 16 turns. Therefore 16 turns tapped at 4 turns should work
for you. Some will say the 3 turns on the 50 ohm side should work and
the secondary then would be turns ratio 4 times that or 12 turns.
Therefore 12 turns tapped at 3 turns should work well also. Sorry, I
do not follow your formula as shown but you can use the above and it
will work fine as an 800 ohm load to the 745 ohm source. This will
reflect 745/16 or 46.6 ohms to your cable. SWR for that at the 50 ohm
cable is 50/46.6 or 1.07 using resistance only for evaluation.
> Lee K7TJR OR
>
> -----Original Message-----
> From: Topband On Behalf Of HA3LN
> Sent: Saturday, January 2, 2021 4:59 AM
> To: topband at contesting.com
> Subject: Topband: (2wire) Beverage transformers
>
> Hi All and HNY for 2021.
>
> Preparing for the CQ160m with new (2 coax) 2-wire beverages to
cover the missing azimuthal gaps based on LBDX. The first 2x Bevs
worked great back in last Jan.
>
> Now I have difficulties with reaching good imped match with the
> T2 transformer (responsible to transform the 745 Ohms wire
impedance to 50 Ohm coax). I use n1=3T/n2=12T tapped @6T transformer
(2m high, 20cm wide with 0.8mm wire)
>
> What can be the reason for the impedance transformation is rather
off to the calculated value?
>
> This is the T2 transformer from 2019:
> http://ha3ln.hu/VNA_190116_230811.jpg
/> > ...and this from yesterday:
> http://ha3ln.hu/VNA_210101_153241.jpg
/> >
> I have
> - same wire with the diam (even from the same roll)
> - same BN73-202 cores (tried to use several cores from different
> sources to eliminate the possible mix inconsistencies)
> - same winding method (including n2 tapping)
> - created a low inductance test resistor network for 744 Ohms
>
> ...tried to wind
> - lousy, and precise (crossing windings vs. side-by-side, bunched
> wires, etc.)
> - n1 first and n2, after n2 first and n1, of course no difference.
> - without the tapping, same as above.
> - difference turning ratios (3/12, 2/12, 1/12, 3/11, etc.) to see
> the change
>
>
> The best I could reach now on 160m is
> - SWR: 1:1.29 (Rs=40.4 Ohms, Xs=-5.4 Ohms) vs. in 2019:
> - SWR: 1:1.16 (Rs=43.2 Ohms, Xs=-1.6 Ohms)
>
> I know, Beverages are really die hard antennas and this increased
mismatch might have zero effect on performance but still, the engineer
part of me...
>
> _________________
> Searchable Archives: http://www.contesting.com/_topband [4] -
Topband Reflector
> _________________
> Searchable Archives: http://www.contesting.com/_topband [5] -
Topband Reflector
>
------------------------------
Message: 6
Date: Sun, 3 Jan 2021 15:51:56 +0100
From: HA3LN
To: topband at contesting.com
Subject: Re: Topband: (2wire) Beverage transformers
Message-ID:
Content-Type: text/plain; charset=utf-8; format=flowed
...thanks Luke, then I stop gold plating... ;-)
One of the new directions is pointing dedicated to VK/ZL
hope I can catch you in the CQ160m.
73!
Csaba
On 2021-01-03 1:39, List Mail wrote:
> "The best I could reach now on 160m is
> - SWR: 1:1.29 (Rs=40.4 Ohms, Xs=-5.4 Ohms)
> vs. in 2019:
> - SWR: 1:1.16 (Rs=43.2 Ohms, Xs=-1.6 Ohms)"
>
>
> If I can get those matches on a *transmitting* antenna, I am very
> satisfied!
>
> I built three 2-wire beverages using W0BTU's design (single coax)
and
> measured best SWR around 1.5:1 and didn't give it a second thought.
They
> are all 269 m long, using 2.5 mm galvanised high-tensile fencing
wire.
> They work!
>
> 73, Luke VK3HJ
> _________________
> Searchable Archives: http://www.contesting.com/_topband [6] -
Topband Reflector
------------------------------
Message: 7
Date: Sun, 3 Jan 2021 08:59:52 -0600
From: Glenn kd0q
To: Randy
Cc: Top Band Contesting
Subject: Re: Topband: Need Ideas For "Fusing" Beverages From Falling
Trees
Message-ID:
Content-Type: text/plain; charset="UTF-8"
Hi Randy,
I have the same situation here and I use 20 GA solid hookup wire for
the
"fuse" with about 10 turns wrapped around itself at the insulators.
Sometimes the wire breaks, sometimes it comes unwrapped. I use butt
splice
crimp connectors on the WD-1A at the "fuse" as they are quick and
easy to
replace. One size smaller wire might be good too but I haven't had to
splice the WD-1A yet. We had a derecho here last August that
basically
flattened my timber. The WD-1A is still good but buried under
countless
blown down trees.
73, Glenn KD0Q
On Sun, Jan 3, 2021 at 5:54 AM Randy via Topband
wrote:
>
> I have several 600 foot beverages made of WD-1A mil wire that run
through
> heavy woods. They can handle the random falling branch but when a
large
> tree falls over them they break. The wire is held in place with
electric
> fence plastic insulators that are nailed to trees every 100 feet. I
would
> like to add a smaller diameter wire to each insulator to act as a
"fuse"
> when a tree falls across them. I am looking for ideas as to the
best way
> to do this. Maybe a number 26 wire? The wire size has to be heavy
enough
> to support the wire in normal use but weak enough to break when hit
by a
> tree. Suggestions? 73 Randy W9ZR
> _________________
> Searchable Archives: http://www.contesting.com/_topband [7] -
Topband
> Reflector
>
------------------------------
Message: 8
Date: Sun, 3 Jan 2021 10:21:06 -0500
From: MU 4CX250B
To: Randy
Cc: topband at contesting.com
Subject: Re: Topband: Need Ideas For "Fusing" Beverages From Falling
Trees
Message-ID:
Content-Type: text/plain; charset="UTF-8"
Hi Randy,
My 720ft beverages (also made of WD1a strung between ceramic
insulstors) have short lengths (12 inches or so) of 26 AWG wire that
act as fuses. Each end of the wire is stapled to the 4 x 4 post at
the
vertex of the beverages. This fuse wire is recommended by DX
Engineerimg to protect the front end of receivers from induced
currents caused by nearby lightning strikes. It does not provide
protection from falling branches or, here in New Mexico, from falling
cacti or wandering bobcats.
However, to me, a mechanical fuse link seems reasonable. As I recall,
WD1a is a twisted pair of wires with a rated breaking strength
greater
than 200 lbs. A short conveniently placed segment of just one of the
conductors would have half the breaking strength, and would be the
likely breaking point if a tree or large branch fell on the antenna.
73,
Jim w8zr
Sent from my iPhone
> On Jan 3, 2021, at 4:54 AM, Randy via Topband wrote:
>
> ?
> I have several 600 foot beverages made of WD-1A mil wire that run
through heavy woods. They can handle the random falling branch but
when a large tree falls over them they break. The wire is held in
place with electric fence plastic insulators that are nailed to trees
every 100 feet. I would like to add a smaller diameter wire to each
insulator to act as a "fuse" when a tree falls across them. I am
looking for ideas as to the best way to do this. Maybe a number 26
wire? The wire size has to be heavy enough to support the wire in
normal use but weak enough to break when hit by a tree. Suggestions?
73 Randy W9ZR
> _________________
> Searchable Archives: http://www.contesting.com/_topband [8] -
Topband Reflector
------------------------------
Message: 9
Date: Sun, 3 Jan 2021 09:02:33 -0700
From: VE6WZ_Steve
To: Randy
Cc: topband at contesting.com
Subject: Re: Topband: Need Ideas For "Fusing" Beverages From Falling
Trees
Message-ID:
Content-Type: text/plain; charset=utf-8
Randy,
I have 15 Beverage wires that average about 900? long. About 2.5
miles of wire. All the wires are in dense, old growth forest.
I have trees falling ALL the time. Every wire has a counterweight
concrete block pulley system to prevent breakage.
When a tree falls on a wire (about twice a month), the wire does not
break, and a quick trip with the chain saw to remove the tree recovers
the wire.
You may not be a ?video guy? but I made a YouTube that shows the
detail of how I install it and how they work:
https://youtu.be/l91JL2ImEbk [9]
/>
And here is a short video showing it in action:
https://youtu.be/GEkA9Hzrwas [10]
/>
Also, for those that have larger Beverage installations, this video
explains how I use my antenna analyzer to sweep my wires at any time
(even remotely) and by comparing the seep to saved files, I know if a
wire is down.
This is NOT a trivial problem. With my Beverage field, to walk and
check all the wires, I would need to walk about 8 miles through heavy
bush! This would take the better part of a day.
Before a contest, in 5 minutes, I can check all 15 wires and know if
there is a tree down or broken term or feed.
https://youtu.be/PA67Tz-1TO4 [11]
/>
73, de steve ve6wz
> On Jan 3, 2021, at 4:54 AM, Randy via Topband wrote:
>
>
> I have several 600 foot beverages made of WD-1A mil wire that run
through heavy woods. They can handle the random falling branch but
when a large tree falls over them they break. The wire is held in
place with electric fence plastic insulators that are nailed to trees
every 100 feet. I would like to add a smaller diameter wire to each
insulator to act as a "fuse" when a tree falls across them. I am
looking for ideas as to the best way to do this. Maybe a number 26
wire? The wire size has to be heavy enough to support the wire in
normal use but weak enough to break when hit by a tree. Suggestions?
73 Randy W9ZR
> _________________
> Searchable Archives: http://www.contesting.com/_topband [12] -
Topband Reflector
------------------------------
Message: 10
Date: Sun, 3 Jan 2021 16:14:57 +0000 (UTC)
From: Roger Parsons
To: Topband
Subject: Topband: Need Ideas For "Fusing" Beverages From Falling
Trees
Message-ID:
Content-Type: text/plain; charset=UTF-8
I have had good success (mostly) following W8JI's recommendations in
a similar situtation with over 30000 ft of Beverages in very rough
woodland:
Use electric fence insulators nailed to trees, but allow the wire to
pass freely through them;
Fix only at the extremes of the antenna;
Use a very strong wire - this is where I diverge from Tom because I
find that WD1A is perfect for Beverages - but not bidirectional ones.
Electric fence wire is probably OK too - and that is W8JI's
recommendation.
At the end points I use an egg insulator and a length of thin Dacron
rope.
WD1A has a major advantage for testing purposes - I make each wire
off separately to a single connection point, and this? allows
resistance measurements to be made from either end of the run to
confirm its continuity.
This arrangement allows the wire to withstand several large trees
falling along its length (1000 ft) - and the antennas keep working.
73 Roger
VE3ZI
------------------------------
Message: 11
Date: Sun, 3 Jan 2021 11:38:03 -0500
From: Mark Robinson
To: Randy , 'topband'
Subject: Re: Topband: Need Ideas For "Fusing" Beverages From Falling
Trees
Message-ID:
Content-Type: text/plain; charset=utf-8; format=flowed
I use 1/4 inch AMP spade connectors , male and female as a breakaway
point on my open wire feeder. I greased them up with dielectric
grease
to keep the water out.?? Automotive bullet connectors might be a
tighter fit
73 Mark N1UK
On 03-Jan-21 6:54 AM, Randy via Topband wrote:
> I have several 600 foot beverages made of WD-1A mil wire that run
through heavy woods.? They can handle the random falling branch but
when a large tree falls over them they break.? The wire is held in
place with electric fence plastic insulators that are nailed to trees
every 100 feet.?I would like to add a smaller diameter wire to each
insulator to act as a "fuse" when a tree falls across them.? I am
looking for ideas as to the best way to do this.? Maybe a number 26
wire?? The wire size has to be heavy enough to support the wire in
normal use but weak enough to break when hit by a
tree.?Suggestions??73?Randy W9ZR
> _________________
> Searchable Archives: http://www.contesting.com/_topband [13] -
Topband Reflector
------------------------------
Message: 12
Date: Sun, 3 Jan 2021 10:52:57 -0600
From: Mark - N5OT
To: TopBand List
Subject: Re: Topband: Need Ideas For "Fusing" Beverages From Falling
Trees
Message-ID:
Content-Type: text/plain; charset=utf-8; format=flowed
> This arrangement allows the wire to withstand several large trees
falling along its length (1000 ft) - and the antennas keep working.
Strange as it sounds, (living where I live and all that), sometimes
during an ice storm all you really want to do is get on the air and
play
radio.? Can't really go out with the chainsaw while it's happening.?
That's for later.
I am liking the counterweight approach as what I may use if I put up
long wires like that.
73 - Mark N5OT
------------------------------
Message: 13
Date: Sun, 3 Jan 2021 16:57:30 +0000 (GMT)
From: CUTTER DAVID
To: Mark Robinson , Randy ,
topband
Subject: Re: Topband: Need Ideas For "Fusing" Beverages From Falling
Trees
Message-ID:
Content-Type: text/plain; charset=UTF-8
Mark
I like that idea the best. I would tie the parts together with a long
piece of rot-proof cord so they don't get lost.
David G3UNA/G6CP
> On 03 January 2021 at 16:38 Mark Robinson wrote:
>
>
> I use 1/4 inch AMP spade connectors , male and female as a
breakaway
> point on my open wire feeder. I greased them up with dielectric
grease
> to keep the water out.?? Automotive bullet connectors might be a
tighter fit
>
> 73 Mark N1UK
------------------------------
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