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Need Help with Antenna Installation

 
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Need Help with Antenna Installation
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rjs
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Joined: 08 Jun 2005
Posts: 1

Post Need Help with Antenna Installation Reply with quote
Using a Max Pro I at 88mhz, and just got a Comet to replace my homemade groundplane antenna. Want to put the Comet in my attic which is maximum 7 feet of vertical space, which is about the total height of the Comet tuned for 88. I'm a novice to LPFM, but have received lots of generous help from PCS and some ham friends. It's my understanding that it's best for the feeder to approach the antenna vertically for several feet. But with the Comet vertical tuned for 88, I won't have vertical space to bring the feeder up vertically, and the feeder will be approaching the antenna horizontally along the floor of the attic and just a few inches below the level of the Comet's horizontals.

I don't have an SWR or scope, can only test by ear. And I know that antenna installation tuning is not an exact science, I'm just requesting everyone's best educated guesses.

For maximum power/distance - is it typically better to tune the vertical as close to my wavelength as possible, with the resulting horizontal feeder, or vice versa?

For low power/short distance (150 feet or so) - is it typically better to tune the vertical as close to my wavelength as possible, with the resulting horizontal feeder, or vice versa, or does it matter?

Thanks in advance, RJ
Wed Jun 08, 2005 3:39 pm View user's profile Send private message
pcs
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Joined: 18 Jan 2002
Posts: 3063
Location: Radio Land

Post Reply with quote
Do you have an old-fashion analogue voltmeter?

Set it to minimal range, mV or uA. Than place it some
20-50m away (as far as possible to still get a comfortable reading)
from the antenna and extend the measuring
cables vertically as an antenna. You should get a reading.
You can play with antenna to get maximum reading, just make sure
you are standing in exact same position every time you readout.

This is a very dirty method, what you should do it get SWR meter
and tune transmitter with dummy load first, than tune antenna
for lowest SWR.

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Wed Jun 08, 2005 5:23 pm View user's profile Send private message Visit poster's website
ai5u
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Joined: 04 Sep 2004
Posts: 14
Location: Lawton/Ft. Sill, OK.

Post Reply with quote
You could use this:

http://www.baproducts.com/images/rpm359.jpg

This would possibly make it easier for your coax installation. I would not be overly-concerned with the routing of the coax (feed-line) cable in a stright -line. Coax cable is designed to be routed in all different directions. You can bend it or loop it if needed.[/url]
Wed Jun 08, 2005 7:38 pm View user's profile Send private message Visit poster's website
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