Re: Topband: Multiband antenna Inv L or top loaded vertical

[Mike Waters]

Trying to find a single antenna that works as well on 160 as it does on 10
is a fool's errand. Sorry.

73, Mike
www.w0btu.com

On Tue, Oct 2, 2018 at 2:14 PM John Randall via Topband <
topband@contesting.com> wrote:

> The new qth is surround by high trees 40ft + and I want to put up a multi
> band L or a top loaded vertical.Ofcourse it must cover topband up to 10m. I
> envisage having to base load the antenna with switchable inductors and
> vacuum caps. I also ponder if going up straight through the branches into
> the clear above the trees is a reasonable idea, compared to putting the alu
> tubing inside the yellow gas tubing pvc and then the tubing sticking out
> the top for the top loading or Inv L wire. Can anyone run a ant simulation
> on both setups and also help on the matching reqd at the base.
> Postage size garden are a hams worst nightmare. Anyone in the US with
> a huge back yard care to swop homes LOL! Pics available on demand ..
>
> 73John -M0ELS
>
>
> _
> Topband Reflector Archives - http://www.contesting.com/_topband
>
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Re: Topband: In L in Tree

[Mike Waters]

Jose (et al), I respectfully and strongly disagree that this QST article
applies to 160m to the degree described in that PDF (which does not even
mention 160 meters!). I DO agree with the findings in that PDF *for those
higher bands*.

However, I do agree that it's probably a bad idea to have the vertical
portion of an inverted-L stapled to a tree trunk. :-)

The effects of nearby trees or woods and their attenuation at 160m have
been discussed to a great length here in the past by many Topbanders far
more experienced than I am. Before anyone takes exception to what I am
saying, please do a search in the Topband Reflector Archive for "trees",
"woods", etc.

My inverted-L (http://www.w0btu.com/160_meters.html) was in a dense woods
of oak trees, and anecdotally I can say that it worked very well indeed,
thank you very much!

And it'll be back up before winter. :-)

73, Mike
www.w0btu.com

On Sun, Sep 23, 2018 at 11:19 AM JC  wrote:

> Hi Ed
>
> One of most impressive study about Tree and antenna performance was
> presented few month ago by Dr. Kay Siwiak, KE4PT during the South Florida
> DX
> association. The study was based on years or resources at Motorola about RF
> on living body.
>
> Live tree does affect RF performance. There are more information on QST Feb
> 2018 pg 35 to 39 , Kai Siwiak, E4PT,and Richard Quick, W4RQ
>
> Here you can download the presentation
>
>
> https://qsl.net/k4fk/presentations/2018-May-02-KE4PT-LiveTrees-SFDXA.pdf
>
> Very interesting stuff. I love the last comments on page 18
>
> "In Practice, everything works, but we don't know why"
>
> " In Theory, we know everything, but nothing works"
>
> We combine Theory and Practice:
> NOTHING WORKS, AND WE DON'T KNOW WHY!
>
>
> 73's
> JC
>
> -Original Message-
> From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Edward
> via Topband
> Sent: Sunday, September 23, 2018 1:40 AM
> To: topband@contesting.com
> Subject: Topband: Inv L in Tree
>
> Has anybody snaked a wire up a tall tree trunk to make an Inv L?
>
> Any interaction?  Success??  Has to be stealthy because the tree os my
> neighbor's :-)
>
> Thanks,
> Ed NI6S
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>
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Topband: Multiband antenna Inv L or top loaded vertical

[John Randall via Topband]

The new qth is surround by high trees 40ft + and I want to put up a multi band 
L or a top loaded vertical.Ofcourse it must cover topband up to 10m. I envisage 
having to base load the antenna with switchable inductors and vacuum caps. I 
also ponder if going up straight through the branches into the clear above the 
trees is a reasonable idea, compared to putting the alu tubing inside the 
yellow gas tubing pvc and then the tubing sticking out the top for the top 
loading or Inv L wire. Can anyone run a ant simulation on both setups and also 
help on the matching reqd at the base.
Postage size garden are a hams worst nightmare.     Anyone in the US with a 
huge back yard care to swop homes LOL! Pics available on demand ..

73John -M0ELS


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Re: Topband: Shunt feeding AB-577/621

[k8gg]

Hi All,

A couple of thoughts:

I used an aluminum powder filled version of Permatex or similar anti-seize
compound the last time I put up an aluminum tower (Heights or Universal). 
No continuity problems.

Also with a rigid galvanized free-standing tower (Probably American Tower
or Pyrod) I used zinc filled anti-seize compound on the face of the
flanges between sections.  No conductivity problems for the 16 years it
was up with a shunt feed for 160 meters.

The AB-577 is probably resonant near 3.5 MHz with the C-3 antenna on top
if one wants to shunt feed it for 80 or 75 meters.

So, I vote for an inverted-L for 160 either supported from the top of the
mast or from a separate tree.

GL & 73,

George, K8GG


> Hi Pete,
>
> Good question. I haven't done it with any of my three AB-577s, but I've
> seen recommendations from others that the sections be electrically bonded.
>
> I'm not sure about the case for that. I just measured continuity on the
> flat portion of a spare tube and it showed zero ohms. If the contact areas
> are clean when the mast is assembled, they should make good contact with
> zero resistance. The clamp should act to keep the flat areas in contact,
> as should the downward pressure from the guys. I guess it may be possible
> that dirt carried by rain water might seep into the clamp and get between
> the sections as they rock back and forth in the wind, even if it's just by
> nanometers.
>
> If you buy that possibility, I think it can be overcome pretty easily by
> attaching right-angle tabs to the top and bottom of each section with
> screws/nuts, and running a section of copper strap between them, also
> secured with screws and nuts, or perhaps you can find some sort of clamp
> that would let you quickly connect/disconnect the strap as you raise/lower
> the mast.
>
> Hope this helps.
>
> 73, Dick WC1M
>
> -Original Message-
> From: N4ZR 
> Sent: Monday, October 1, 2018 11:48 AM
> To: topband reflector 
> Subject: Topband: Shunt feeding AB-577/621
>
> I have an AB-577 with a C-3E on top, and am interested in the possibility
> of shunt-feeding it for 160 - 100 watts only.  Anyone have any experience
> with doing this?  Are the section-to-section joints adequately conductive?
>  I would plan to use an omega match, because I'm guessing it would be well
> short of a quarter wave.
>
> My other option is an inverted L.  Should I maybe just go ahead with that?
>
> --
>
> 73, Pete N4ZR
> Check out the Reverse Beacon Network
> at , now
> spotting RTTY activity worldwide.
> For spots, please use your favorite
> "retail" DX cluster.
>
>
>
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> Topband Reflector Archives - http://www.contesting.com/_topband
>


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Re: Topband: Shunt feeding AB-577/621

[Dick Green WC1M]

Hi Pete,

Good question. I haven't done it with any of my three AB-577s, but I've seen 
recommendations from others that the sections be electrically bonded. 

I'm not sure about the case for that. I just measured continuity on the flat 
portion of a spare tube and it showed zero ohms. If the contact areas are clean 
when the mast is assembled, they should make good contact with zero resistance. 
The clamp should act to keep the flat areas in contact, as should the downward 
pressure from the guys. I guess it may be possible that dirt carried by rain 
water might seep into the clamp and get between the sections as they rock back 
and forth in the wind, even if it's just by nanometers.

If you buy that possibility, I think it can be overcome pretty easily by 
attaching right-angle tabs to the top and bottom of each section with 
screws/nuts, and running a section of copper strap between them, also secured 
with screws and nuts, or perhaps you can find some sort of clamp that would let 
you quickly connect/disconnect the strap as you raise/lower the mast.

Hope this helps.

73, Dick WC1M

-Original Message-
From: N4ZR  
Sent: Monday, October 1, 2018 11:48 AM
To: topband reflector 
Subject: Topband: Shunt feeding AB-577/621

I have an AB-577 with a C-3E on top, and am interested in the possibility of 
shunt-feeding it for 160 - 100 watts only.  Anyone have any experience with 
doing this?  Are the section-to-section joints adequately conductive?  I would 
plan to use an omega match, because I'm guessing it would be well short of a 
quarter wave.

My other option is an inverted L.  Should I maybe just go ahead with that?

-- 

73, Pete N4ZR
Check out the Reverse Beacon Network
at , now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.



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