Thread: NVIS and VHF?
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Old June 1st 11, 11:47 PM posted to rec.radio.amateur.antenna
John S John S is offline
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First recorded activity by RadioBanter: May 2011
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Default NVIS and VHF? (Update)

On 6/1/2011 4:48 PM, 'Captain' Kirk DeHaan wrote:

I am still working on finding where the problem is. I pulled the J-pole
down and checked the resistance of the separate connections. I didn't
want to pull it apart if not necessary. Everything showed 0.0 to 0.1
ohms. Seems fine to me. I then cleaned the connector as throughly as
possible using emory cloth inside and dremeled the outside with a fine
wire brush. There was a small amount of oxidation and it appeared much
cleaner and brighter after. I also straightened the two elements but
they were not really that bent. You had to look down the long axis to
see any deviation. They are as straight as they are going to get but I
can't believe that would make much difference.

After all this I put it back up to it's original height. There was not
discernible change. I was almost unreadable at the repeater.

Next I pushed up my mast a few feet more. It is a 50' pushup that
normally requires guy wires. I am not using any so I am leaving
considerable overlap of the sections. I would estimate it is up around
32'. Even in high winds here I saw little deflection with just the
J-pole. The 3 or 4 feet I pushed it up gave me a little bit of
improvement. When I win the lottery I'll get a 100' tower put up. Guess
I'm stuck with this then :-)

I still think it is the trees and have taken a picture from the roof
peak towards the repeater so you can see what I am dealing with.

http://www.ncc-1701a.net/Ham Radio/ForestObstruction.jpg

It is deceiving as there are many more trees behind this line on my
neighbors property. I wouldn't even think of asking him to cut any. They
are money in the bank for him.


Kirk -

Do you have parts on hand such as extra coax, connectors, wire, etc?

Although you have done a thorough job of examining your installation, it
behoove you to make a test separate from your present antenna installation.

For example, you could simply strip 1/4WL from the end of a coax feeder
and put that end on the roof temporarily. I know, not the best match,
common mode currents down the line, signal launches upward, etc. But, it
is simple and might tell you something.

Maybe a quick, thrown-together ground plane?

Just a thought.

73,
John