Re: Topband: Looking for user experience: DXEngineering Thunderbolt 160m vertical

[Dave Cuthbert]

David,

the capacity hat does cancel some radiation. Think of RF current going up
the mast and down the top hat wires. The magnetic fields partially cancel.

Without the capacity hat wires the 55' mast exhibits a radiation resistance
of ~5 ohms. With the capacity hat it is also ~5 ohms. So, nothing is lost
there. Where the capacity hat comes into play is to increase bandwidth.
Without the capacity hat, and using 3 ohms for GND + coil loss, the 2:1
VSWR bandwidth is ~20kHz. With the capacity hat it is ~40kHz.

The capacity hat improves the SWR bandwidth while increasing radiation
efficiency a bit.

I think the antenna radiation efficiency might be improved with a
capacity hat that does not extend down as far. A smaller capacity hat will
give higher radiation resistance along with greater loading inductance.

*I can run some models if you'd like to find an optimum top hat size based
on a coil Q of 400(?) and for various GND loss resistances. *

   Dave KH6AQ

On Sat, Dec 5, 2020 at 3:37 AM David Aslin G3WGN  wrote:

> I'm building a contest station and the time has come to make a choice of
> 160m TX antenna. Looking at DXE Thunderbolt I note that the capacity hat
> extends to a significant distance down the vertical section. It's my
> understanding that will shield some of the radiation from the upper part of
> the vertical. Alternatives like a vertical tee would not have this issue.
> Is my understanding correct?
>
> I'm considering a commercial antenna as high strength telescoping antenna
> tubing is unobtanium in UK.  My QTH is an exposed windy location so
> strength matters!
> 73, David G3WGN M6O
>
>
>
> Sent from my Galaxy
>
> _
> Searchable Archives: http://www.contesting.com/_topband - Topband
> Reflector
>
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Looking for user experience: DXEngineering Thunderbolt 160m vertical

[Jim Brown]

On 12/5/2020 5:37 AM, David Aslin G3WGN wrote:

I note that the capacity hat extends to a significant distance down the 
vertical section. It's my understanding that will shield some of the radiation 
from the upper part of the vertical.


Yes and no. The sloping hat reduces the effective height, which reduces 
the radiation resistance, thus the feedpoint impedance, but most of the 
radiation is from the part of the antenna where current is greatest, 
which is at the base.


There are many ways to match it, as shown by other responses in this 
thread. Remember also that coax loss on 160M is small, so unless the run 
is quite long, the major concern is whether the power amp is happy with 
the load it sees. My 87As are picky, my KPA1500 is not.


And no matter the details of the vertical radiator, a serious 
radial/counterpoise is critical to minimize losses in the soil.


73, Jim K9YC


_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Looking for user experience: DXEngineering Thunderbolt 160m vertical

[Dave Cuthbert]

I refined the DX Engineering Thunderbolt EZNEC model to be exactly like the
actual antennat by changing the capacity hat wire size.

It is resonant at 1930kHz. 2.15uH of series inductance tunes it to 1820kHz
where the input impedance is 4.8 ohms. GND + coil loss of 3.2 ohms gives
the claimed DX Engineering typical 2:1 SWR bandwidth of 40kHz. Radiation
efficiency -- if you can get a 3 ohm GND, is 60%.

Dave KH6AQ

On Sat, Dec 5, 2020 at 7:49 AM Dave Cuthbert  wrote:

> The DX Engineering Thunderbolt antenna includes a means to resonate and
> match the antenna using a series inductor and a  shunt inductor. *It does
> not require a balun*.
> See the manual:
> https://static.dxengineering.com/global/images/instructions/dxe-160va-1_jj.pdf
>
> An EZNEC model shows it to be resonant at 1825 kHz with an input impedance
> of *4.0 ohms*. Adding 2.5 ohms of GND + coil loss it shows a 2:1 VSWR
> bandwidth of 40 kHz. This agrees with the DX Engineering SWR graph on page
> 43. If your installation has 2.5 ohm base referred GND/coil loss the
> radiation efficiency will be ~60%.
>
> Dave KH6AQ
>
>
>
> On Sat, Dec 5, 2020 at 5:39 AM Wes  wrote:
>
>> Or reduce the loading to present a capacitive reactance at the feedpoint
>> and
>> shunt it with an inductor.  Functions as a step up L-network and presents
>> a
>> ground at DC.  That's what I do here.
>>
>> Wes  N7WS
>>
>>
>> On 12/5/2020 7:35 AM, Rudy Bakalov via Topband wrote:
>> > 
>> > P.S. If your vertical has a good set of radials, you will see about 35
>> Ohm feedpoint impedance. You may want to wind your own unun using Jerry
>> Sevick’s cookbook
>> >
>> >
>> http://www.introni.it/pdf/Amidon%20-%20Transmission%20Line%20Transformers%20Handbook.pdf
>> >
>> > or buy a readymade 35 to 50 Ohm unun from balundesigns.com
>> >
>> > The third option is to build a coax transformer per PA0FRI.
>> >
>> >
>> >
>> > Rudy N2WQ
>> >
>> > Sent using a tiny keyboard.  Please excuse brevity, typos, or
>> inappropriate autocorrect.
>> >
>> >
>> >> On Dec 5, 2020, at 8:37 AM, David Aslin G3WGN 
>> wrote:
>> >> I'm building a contest station and the time has come to make a choice
>> of 160m TX antenna. Looking at DXE Thunderbolt I note that the capacity hat
>> extends to a significant distance down the vertical section. It's my
>> understanding that will shield some of the radiation from the upper part of
>> the vertical. Alternatives like a vertical tee would not have this issue.
>> >> Is my understanding correct?
>> >>
>> >> I'm considering a commercial antenna as high strength telescoping
>> antenna tubing is unobtanium in UK.  My QTH is an exposed windy location so
>> strength matters!
>> >> 73, David G3WGN M6O
>> >>
>> >>
>> >>
>> >> Sent from my Galaxy
>> >>
>> >> _
>> >> Searchable Archives: http://www.contesting.com/_topband - Topband
>> Reflector
>> > _
>> > Searchable Archives: http://www.contesting.com/_topband - Topband
>> Reflector
>>
>>
>> _
>> Searchable Archives: http://www.contesting.com/_topband - Topband
>> Reflector
>>
>
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Looking for user experience: DXEngineering Thunderbolt 160m vertical

[W0MU Mike Fatchett]

I have one of the DXE 80m verticals and it is great.  The ability to 
crank up and down is nice, although I have never taken it down since I 
put it up.  The thing is a tank!


I have an inverted L for 160 so I never considered using it on 160.

W0MU

On 12/5/2020 11:26 AM, MU 4CX250B wrote:

Hi David,
I live in a windy area with 100km frequent wind gusts in the spring. I
bought a DXE heavy duty 80m self-supporting tilt-over vertical on the
advice of a professional tower guy. It was expensive and the assembly took
a couple of days, but the result was worth it. It seemed built to mil-spec
standards, with heavy aluminum tubing, heavy stainless steel hardware, and
heavy duty winch. I have since added a base loading coil and remote vacuum
relay to convert it to a duo-band 80m/160m antenna with 60 120ft radials.
It takes five minutes to crank over. Here’s the web link:

https://www.dxengineering.com/parts/dxe-7580fs-va-
3
73,
Jim w8zr

Sent from my iPhone

On Dec 5, 2020, at 6:37 AM, David Aslin G3WGN  wrote:

I'm building a contest station and the time has come to make a choice of
160m TX antenna. Looking at DXE Thunderbolt I note that the capacity hat
extends to a significant distance down the vertical section. It's my
understanding that will shield some of the radiation from the upper part of
the vertical. Alternatives like a vertical tee would not have this issue.
Is my understanding correct?

I'm considering a commercial antenna as high strength telescoping antenna
tubing is unobtanium in UK.  My QTH is an exposed windy location so
strength matters!
73, David G3WGN M6O



Sent from my Galaxy

_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector


_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Looking for user experience: DXEngineering Thunderbolt 160m vertical

[MU 4CX250B]

Hi David,
I live in a windy area with 100km frequent wind gusts in the spring. I
bought a DXE heavy duty 80m self-supporting tilt-over vertical on the
advice of a professional tower guy. It was expensive and the assembly took
a couple of days, but the result was worth it. It seemed built to mil-spec
standards, with heavy aluminum tubing, heavy stainless steel hardware, and
heavy duty winch. I have since added a base loading coil and remote vacuum
relay to convert it to a duo-band 80m/160m antenna with 60 120ft radials.
It takes five minutes to crank over. Here’s the web link:

https://www.dxengineering.com/parts/dxe-7580fs-va-
3
73,
Jim w8zr

Sent from my iPhone

On Dec 5, 2020, at 6:37 AM, David Aslin G3WGN  wrote:

I'm building a contest station and the time has come to make a choice of
160m TX antenna. Looking at DXE Thunderbolt I note that the capacity hat
extends to a significant distance down the vertical section. It's my
understanding that will shield some of the radiation from the upper part of
the vertical. Alternatives like a vertical tee would not have this issue.
Is my understanding correct?

I'm considering a commercial antenna as high strength telescoping antenna
tubing is unobtanium in UK.  My QTH is an exposed windy location so
strength matters!
73, David G3WGN M6O



Sent from my Galaxy

_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Looking for user experience: DXEngineering Thunderbolt 160m vertical

[Dave Cuthbert]

The DX Engineering Thunderbolt antenna includes a means to resonate and
match the antenna using a series inductor and a  shunt inductor. *It does
not require a balun*.
See the manual:
https://static.dxengineering.com/global/images/instructions/dxe-160va-1_jj.pdf

An EZNEC model shows it to be resonant at 1825 kHz with an input impedance
of *4.0 ohms*. Adding 2.5 ohms of GND + coil loss it shows a 2:1 VSWR
bandwidth of 40 kHz. This agrees with the DX Engineering SWR graph on page
43. If your installation has 2.5 ohm base referred GND/coil loss the
radiation efficiency will be ~60%.

Dave KH6AQ



On Sat, Dec 5, 2020 at 5:39 AM Wes  wrote:

> Or reduce the loading to present a capacitive reactance at the feedpoint
> and
> shunt it with an inductor.  Functions as a step up L-network and presents
> a
> ground at DC.  That's what I do here.
>
> Wes  N7WS
>
>
> On 12/5/2020 7:35 AM, Rudy Bakalov via Topband wrote:
> > 
> > P.S. If your vertical has a good set of radials, you will see about 35
> Ohm feedpoint impedance. You may want to wind your own unun using Jerry
> Sevick’s cookbook
> >
> >
> http://www.introni.it/pdf/Amidon%20-%20Transmission%20Line%20Transformers%20Handbook.pdf
> >
> > or buy a readymade 35 to 50 Ohm unun from balundesigns.com
> >
> > The third option is to build a coax transformer per PA0FRI.
> >
> >
> >
> > Rudy N2WQ
> >
> > Sent using a tiny keyboard.  Please excuse brevity, typos, or
> inappropriate autocorrect.
> >
> >
> >> On Dec 5, 2020, at 8:37 AM, David Aslin G3WGN 
> wrote:
> >> I'm building a contest station and the time has come to make a choice
> of 160m TX antenna. Looking at DXE Thunderbolt I note that the capacity hat
> extends to a significant distance down the vertical section. It's my
> understanding that will shield some of the radiation from the upper part of
> the vertical. Alternatives like a vertical tee would not have this issue.
> >> Is my understanding correct?
> >>
> >> I'm considering a commercial antenna as high strength telescoping
> antenna tubing is unobtanium in UK.  My QTH is an exposed windy location so
> strength matters!
> >> 73, David G3WGN M6O
> >>
> >>
> >>
> >> Sent from my Galaxy
> >>
> >> _
> >> Searchable Archives: http://www.contesting.com/_topband - Topband
> Reflector
> > _
> > Searchable Archives: http://www.contesting.com/_topband - Topband
> Reflector
>
>
> _
> Searchable Archives: http://www.contesting.com/_topband - Topband
> Reflector
>
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Looking for user experience: DXEngineering Thunderbolt 160m vertical

[Wes]

Or reduce the loading to present a capacitive reactance at the feedpoint and 
shunt it with an inductor.  Functions as a step up L-network and presents a 
ground at DC.  That's what I do here.


Wes  N7WS


On 12/5/2020 7:35 AM, Rudy Bakalov via Topband wrote:


P.S. If your vertical has a good set of radials, you will see about 35 Ohm 
feedpoint impedance. You may want to wind your own unun using Jerry Sevick’s 
cookbook

http://www.introni.it/pdf/Amidon%20-%20Transmission%20Line%20Transformers%20Handbook.pdf

or buy a readymade 35 to 50 Ohm unun from balundesigns.com

The third option is to build a coax transformer per PA0FRI.



Rudy N2WQ

Sent using a tiny keyboard.  Please excuse brevity, typos, or inappropriate 
autocorrect.



On Dec 5, 2020, at 8:37 AM, David Aslin G3WGN  wrote:
I'm building a contest station and the time has come to make a choice of 160m 
TX antenna. Looking at DXE Thunderbolt I note that the capacity hat extends to 
a significant distance down the vertical section. It's my understanding that 
will shield some of the radiation from the upper part of the vertical. 
Alternatives like a vertical tee would not have this issue.
Is my understanding correct?

I'm considering a commercial antenna as high strength telescoping antenna 
tubing is unobtanium in UK.  My QTH is an exposed windy location so strength 
matters!
73, David G3WGN M6O



Sent from my Galaxy

_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector



_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Looking for user experience: DXEngineering Thunderbolt 160m vertical

[Rudy Bakalov via Topband]


P.S. If your vertical has a good set of radials, you will see about 35 Ohm 
feedpoint impedance. You may want to wind your own unun using Jerry Sevick’s 
cookbook

http://www.introni.it/pdf/Amidon%20-%20Transmission%20Line%20Transformers%20Handbook.pdf

or buy a readymade 35 to 50 Ohm unun from balundesigns.com

The third option is to build a coax transformer per PA0FRI.



Rudy N2WQ 

Sent using a tiny keyboard.  Please excuse brevity, typos, or inappropriate 
autocorrect.


> On Dec 5, 2020, at 8:37 AM, David Aslin G3WGN  wrote:
> I'm building a contest station and the time has come to make a choice of 
> 160m TX antenna. Looking at DXE Thunderbolt I note that the capacity hat 
> extends to a significant distance down the vertical section. It's my 
> understanding that will shield some of the radiation from the upper part of 
> the vertical. Alternatives like a vertical tee would not have this issue.
> Is my understanding correct?
> 
> I'm considering a commercial antenna as high strength telescoping antenna 
> tubing is unobtanium in UK.  My QTH is an exposed windy location so strength 
> matters!
> 73, David G3WGN M6O
> 
> 
> 
> Sent from my Galaxy
> 
> _
> Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Looking for user experience: DXEngineering Thunderbolt 160m vertical

[Rudy Bakalov via Topband]

David,

Are you thinking of buying from DXE and importing? If yes, you may as well 
consider buying the aluminum from them and build the vertical exactly the way 
you want it. This is what we did at HQ9X for the 160, 80, and 40 meter 
verticals.

Rudy N2WQ 

Sent using a tiny keyboard.  Please excuse brevity, typos, or inappropriate 
autocorrect.


> On Dec 5, 2020, at 8:37 AM, David Aslin G3WGN  wrote:
> 
> I'm building a contest station and the time has come to make a choice of 
> 160m TX antenna. Looking at DXE Thunderbolt I note that the capacity hat 
> extends to a significant distance down the vertical section. It's my 
> understanding that will shield some of the radiation from the upper part of 
> the vertical. Alternatives like a vertical tee would not have this issue.
> Is my understanding correct?
> 
> I'm considering a commercial antenna as high strength telescoping antenna 
> tubing is unobtanium in UK.  My QTH is an exposed windy location so strength 
> matters!
> 73, David G3WGN M6O
> 
> 
> 
> Sent from my Galaxy
> 
> _
> Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Looking for user experience: DXEngineering Thunderbolt 160m vertical

[clive]

Dave that seems expensive and not cost effective. I would use two scaffold
20' poles plus a lighter gauge top section of similar dia.
You can buy aircraft grade DIN tubing 6082 which is slightly better than
6061 T6. Make the height somewhere in the 55ft region and use two top
loading wires of Stainless Steel. Overall cost a fraction of your initial
thought and will work at least as well.
Use it with a hairpin that is what I use here. 73 Clive GM3POI/GM3X  

-Original Message-
From: Topband  On Behalf Of
David Aslin G3WGN
Sent: 05 December 2020 13:37
To: topband@contesting.com
Subject: Topband: Looking for user experience: DXEngineering Thunderbolt
160m vertical

I'm building a contest station and the time has come to make a choice of
160m TX antenna. Looking at DXE Thunderbolt I note that the capacity hat
extends to a significant distance down the vertical section. It's my
understanding that will shield some of the radiation from the upper part of
the vertical. Alternatives like a vertical tee would not have this issue.
Is my understanding correct?

I'm considering a commercial antenna as high strength telescoping antenna
tubing is unobtanium in UK.  My QTH is an exposed windy location so strength
matters!
73, David G3WGN M6O



Sent from my Galaxy

_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector