Topband: Suggestions for a tower?

[Ashton Lee]

Or an easy and fairly good approach is to set up a sloper off the tower. The sloper acts as an inverted vertical ( inverted verticals work better than ground fed ones) and uses the grounded tower as its ground. Basically you run your feed line to the top of the tower, run the hot core to a wire slanted down and away from the tower and connect the ground to the tower. I ended up with the best match using a 130 foot wire and feeding through a 4:1 unun. Slopers are a bit tricky as each installation requires some trial and error. But they work darn well.

Also, while you will get some counter argument, setting up an inverted V off the tower top will work very well too. That may have a higher angle of radiation but will be very easy to tune to a 50 ohm match.




On Apr 23, 2014, at 5:19 PM, Jon Zaimes AA1K <jz73 at verizon.net> wrote:

> Jaan,
> 
> Before replacing the guys, you might consider trying a gamma match at the bottom end of one of the top guy wires to load the tower and guys as-is. I did something similar on a sailboat for 80 meters (gamma matching the rigging on a 35-foot-high mast)  and it worked OK.
> 
> 73/Jon AA1K
> 
> 
> On 4/23/2014 8:15 AM, Jaan Jürgenson wrote:
>> Hello low banders.
>> 
>> My name is Jaan and I have been reading all kinds of interesting things
>> regarding propagation, antennas and other topics here on this reflector. I
>> hope to receive some valuable comments, recflections and also hands on
>> experience on my question.
>> 
>> Last winter I became active on 160 and found it very exciting with
>> propagation and activity on this band. What I would like to ask is what
>> would You propose for antenna?
>> 
>> Background:
>> I have a tower that is 137ft. or 42m tall. It is triangular 1ft 10inches or
>> 40cm wide. The tower is guy wired at three levels with non-isolated wire.
>> The foundation is a concrete slab on on rocky ground.
>> The surroundings is quite flat and conductivity is perhaps not the best.
>> About 1/2 mile away I have the Baltic Ocean in almost 360 degrees.
>> 
>> My question is what options do I have to build a good TX antenna out of
>> this? What can I do? On RX side I will use separate antennas.
>> I could think of isolating the guy wires or replace them for non-conductive
>> type. I'm not sure if it possible to isolate the base today. Shunt fed the
>> tower, use it as a folded monopole? Or should I just use the tower as a
>> support for a L-antenna?
>> 
>> 73 de Jaan, SM0OEK
>> _________________
>> Topband Reflector Archives - http://www.contesting.com/_topband
>> 
> 
> _________________
> Topband Reflector Archives - http://www.contesting.com/_topband
>