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Old 05-15-2012, 3:37 PM
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Default SO-239 dual band?

I made one for 460MHz as shown in the first link below. All my radials are as shown in the first link. It works pretty good.

Then I ran across the multi band ground plane at the second link below.

I am looking to make a 460/800, dual band ground plane. I really dont have the space or need for the 150MHz band. I do have a few 800MHz systems.

I made a 3 1/4 element as shown in the multi band directions. My issue is I do not have the 19'' vertical element, as shown in the multi band. I have a 6'' element.

My question is, how far up the 6'' vertical do I attach the 3 1/4 element if this can even be done?

460 band
Ground Plane photo - Dick Harris photos at pbase.com

multi band
http://www.qsl.net/n4yek/scanner/antenna.pdf
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Old 05-15-2012, 8:12 PM
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It looks as if all the dimensions you need are on the diagram. The dimension shown for the 3.25" element is 7 inches from the bottom.
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Old 05-15-2012, 8:27 PM
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Quote:
Originally Posted by W2NJS View Post
It looks as if all the dimensions you need are on the diagram. The dimension shown for the 3.25" element is 7 inches from the bottom.
I think you misread my post..

The ground plane I made is for 460MHz and the center element is only 6'' long.

I would like to know where to add the 3 1/4 800MHz element, if this will even work..
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Old 05-16-2012, 12:28 AM
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Its easy if they share the same feedpoint. You can first make the 6" 460MHz element stick straight out of the connector then attach the 3 1/4" 800MHz element right where the 6" element first exits the connector but first bring the 800 element sideways for maybe 3/4" then bend it straight up. The whips will interact a bit and should be tuned but your dimensions should be close enough to work.

I was doing basically the same thing about an hour ago modifying an AOR SA-7000 to improve FM broadcast and NOAA 162MHz weather.

I threw away the stock mystery loaded whip which doesn't resonate anywhere I needed it and replaced with a 32" whip tuned to 98MHz with a secondary 16" whip tuned to 162MHz attached to the same feedpoint with a tiny SS hose clamp and it bends away from the long whip about 2" before going straight up.

I measured the stock antenna at 162MHz then after modification and 162MHz weather came up about 12dB over the stock whip, which is not a trivial amount and it proves the two whips can coexist.
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Quote:
Originally Posted by dave3825 View Post
I think you misread my post..

The ground plane I made is for 460MHz and the center element is only 6'' long.

I would like to know where to add the 3 1/4 800MHz element, if this will even work..
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Old 01-07-2013, 1:58 PM
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what type solder did you use? and how hot does it need to be to solder good? i wanna build one of these but i dont have any soldering experience or anything but i want to learn so i can start making antennas?
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Old 01-07-2013, 2:24 PM
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All of those 'elements' can be directly connected to the SO-239 connector's center pin. Spread them out a bit to separate them.
How hot to get the solder to melt it? I can't give you temperature in degrees, don't think I ever knew. Very basically, if the 'iron/gun' will melt the stuff then it should work. Lots of different 'kinds' of solder, try it and see?
- 'Doc
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Old 01-07-2013, 2:45 PM
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Simple soldering! Heat whatever you are soldering until it melts the solder. The soldering gun/iron doesn't melt the solder, what you are soldering should melt the solder. Place the gun/iron on the opposite side of the applied solder. The solder should melt and flow smoothly around what you are trying to solder. Use rosin core (flux) solder. DO NOT USE ACID CORE SOLDER.

Just remember to use the gun/iron to heat the work and let the work melt the solder. Good Luck!

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Old 01-07-2013, 3:27 PM
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ok i thanks i want to learn this so i can start making more antennas
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