Topband: Visalia Top Band Dinner

[wb6rse1]

The 2017 Top Band Dinner at the Visalia International DX Convention will be 
held on Friday, April 21, 2017 at the Marriott Hotel immediately adjacent to 
the Visalia Convention Center.

Registration, program, menu and cost information can be found on the dinner’s 
website:

https://topbanddinner.jimdo.com 

Early registration is strongly recommended.


73 - Steve WB6RSE
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Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: tower vertical

[Rob Atkinson]

Bob,

You didn't mention the model or manufacturer of your tower.The
best installation involves a genuine tapered bottom section of the
type made to accommodate a ceramic base insulator.   Usually when you
find one, you also get the mounting hardware and ball gap that
accompanies it.   You have to construct a concrete pier so the
insulator is elevated.  This keeps it up above water, snow, blowing
debris etc.  You have to have four copper straps coming down from the
bottom of the insulator to the ground system so that the concrete does
not have voltage across it--only the insulator should.   The tapered
or cylindrical insulator and tapered bottom section should seat into a
pin hole on the bottom hardware mount allowing the tower to rotate so
there is no twisting of the tower.  Obviously you need to guy the
tower as it is not free standing and the guys must either be RF
transparent or be broken up with johnny ball insulators so they do not
distort the pattern.

If you want to employ a free standing tower, or if you cannot find a
bottom section or insulator or both, you can construct a tower and
skirt feed it.  You line the tower with 3 or 4 hot wires on insulators
running up the sides with horizontal rings connecting them to each
other every 20 feet or so and a ring at the top and bottom.   If the
tower is guyed you'll still need to break up the guys so they don't
distort the pattern.   Either way a quarter wave vertical with 100+
quarter wave radials will be a great flame thrower.

There's no need to reinvent the wheel.  You can find a lot of photos
on-line of broadcast tower bases.  This page should give you some
ideas:  http://www.amgroundsystems.com/projects_2013.html

73

Rob
K5UJ
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Topband Reflector Archives - http://www.contesting.com/_topband

Topband: tower vertical

[StellarCAT]

Hello Bob,

When I’ve modeled a 160 vertical interior to an 80M 4 sq I find the vertical 
interacts terribly with the 4 sq. The ‘tower’ would need to be broken up in to 
3 sections ... not a simple task... I know there are those that have done this 
but I suspect they’ve just put it up and taken the results as is ... 

just a thought... 

Gary 
K9RX


xxx
Hi I have decided to put up a 40m tower to use as a transmitting vertical for 
1.8mHz out away from in between our other towers and where I can run 1/4 wave 
radials all the way around, and will probably use locally available 12" steel 
sections with a conical-type pin base. I would like to insulate the base in 
order to make it easier to detune on receive (this will be located in the exact 
center of our 8 circle rx arrays). Has anyone used HDPE or similar to make a 
homebrew base insulator for a tower monopole? Any other comments about the need 
for a base insulator also welcome.73 Bob HS0ZIA
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Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: tower vertical

[Brian Pease]

The base insulator is certainly the most effective way to detune, and 
the most efficient way to drive the tower, but it is nice to have the 
tower grounded and use shunt feed.  You can detune the tower by turning 
the bottom section into a parallel-resonant trap during receive, 
probably using the TX shunt wire with a series capacitor to the bottom.  
See ON4UNs book pg 7-109


On 1/31/2017 12:49 AM, Bob Kupps via Topband wrote:

Hi I have decided to put up a 40m tower to use as a transmitting vertical for 1.8mHz 
out away from in between our other towers and where I can run 1/4 wave radials all 
the way around, and will probably use locally available 12" steel sections with 
a conical-type pin base. I would like to insulate the base in order to make it 
easier to detune on receive (this will be located in the exact center of our 8 
circle rx arrays). Has anyone used HDPE or similar to make a homebrew base insulator 
for a tower monopole? Any other comments about the need for a base insulator also 
welcome.
73 Bob HS0ZIA

Sent from Yahoo Mail on Android
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Topband Reflector Archives - http://www.contesting.com/_topband



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