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HomerBB
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Post subject: Knockarounds
 Posted: Mar 24, 2010 - 11:27 PM
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DX Alpha
Joined: Mar 18, 2010
Posts: 687
Location: NW Arkansas USA
Status: Offline
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Just because it occurred to me to do so I put these two antennas together.
1.) The first was intended to be the driven element of a shortened/coil loaded Yagi. It had great SWR near the ground, but when I put it up over ten feet high the SWR began to go up.
On a lark, I decided to see what it did on the SUV. It was really stinky horizontal over the roof, But when I brought it down and stuck it through the back window vertically the SWR improved greatly and RX/TX was good. I made a make-shift bracket from junk to see how it would do outside the the vehicle.
SWR
27.405 1.3:1
27.185 1.0:1
26.985 1.2:1
2.) The second is simply a horizontal dipole bent inward in the middle to 45*. At 12 feet up it has an impressive SWR.
SWR
28.755 1.1:1
28.305 1.0:1
27.855 1.1:1
27.415 1.2:1
26.965 1.3:1
26.515 1.5:1
26.065 1.8:1
25.615 2.5:1
25.165 3.3:1
Who'd a thought  |
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HomerBB
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Post subject:
Posted: Mar 24, 2010 - 11:27 PM
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DX Alpha
Joined: Mar 18, 2010
Posts: 687
Location: NW Arkansas USA
Status: Offline
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I need to mention that the dipole on the back of the car was meant to be the driven element of a three element shortened/loaded Yagi. So, I decided to go forward with the three element Yagi. I put the knockround dipole into the Yagi and here are results so far.
Look here:
Loaded 3el Yagi for CB
I will do more work on it and get it up higher later. |
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HomerBB
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Post subject:
Posted: Mar 25, 2010 - 08:24 PM
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DX Alpha
Joined: Mar 18, 2010
Posts: 687
Location: NW Arkansas USA
Status: Offline
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HomerBB wrote:
I need to mention that the dipole on the back of the car was meant to be the driven element of a three element shortened/loaded Yagi. So, I decided to go forward with the three element Yagi. I put the knockround dipole into the Yagi and here are results so far.
Look here:
Loaded 3el Yagi for CB
I will do more work on it and get it up higher later.
The info on the construction of the dipole is now at the original link: Loaded 3el Yagi For CB |
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HomerBB
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Post subject:
Posted: Mar 26, 2010 - 12:24 AM
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DX Alpha
Joined: Mar 18, 2010
Posts: 687
Location: NW Arkansas USA
Status: Offline
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HomerBB wrote:
HomerBB wrote:
I need to mention that the dipole on the back of the car was meant to be the driven element of a three element shortened/loaded Yagi. So, I decided to go forward with the three element Yagi. I put the knockround dipole into the Yagi and here are results so far.
Look here:
Loaded 3el Yagi for CB
I will do more work on it and get it up higher later.
The info on the construction of the dipole is now at the original link: Loaded 3el Yagi For CB
Apparently the site is down temporarily. If interested, try again later. |
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213
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Post subject:
Posted: Mar 26, 2010 - 06:45 AM
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Moderator
Joined: Nov 02, 2007
Posts: 88
Status: Offline
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| interesting stuff there homer keep it up the best antenna designers start by experimenting |
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HomerBB
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Post subject:
Posted: Mar 26, 2010 - 12:16 PM
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DX Alpha
Joined: Mar 18, 2010
Posts: 687
Location: NW Arkansas USA
Status: Offline
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Thanks. I'm just having fun constantly thinking of fixes, or possibilities.
There's more at the site under Projects - Interestingly Enough - if interested. |
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213
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Post subject:
Posted: Mar 28, 2010 - 07:59 AM
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Moderator
Joined: Nov 02, 2007
Posts: 88
Status: Offline
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| keep us updated... i like to see stuff like this have you ever played with j-poles? i hear they are fun to mess with |
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HomerBB
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Post subject:
Posted: Mar 28, 2010 - 12:26 PM
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DX Alpha
Joined: Mar 18, 2010
Posts: 687
Location: NW Arkansas USA
Status: Offline
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213 wrote:
keep us updated... i like to see stuff like this have you ever played with j-poles? i hear they are fun to mess with
No j-poles, yet. I've looked at them, but on 27Mhz they are pretty big. I'd need a lot of pipe and support for one. |
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HomerBB
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Post subject:
Posted: Jun 18, 2010 - 12:53 AM
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DX Alpha
Joined: Mar 18, 2010
Posts: 687
Location: NW Arkansas USA
Status: Offline
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Another knockaround done for a 1/4 wave ground plane contest:
1/4 wave GP made of chicken wire. The poultry wire is wrapped around a 4 inch waste pipe. The counterpoise is also made of poultry wire.
The antenna works. Where it is sitting in the photo the SWR is 1:4.1 on 27.185. I received and spoke to a trucker on channel 19.
Last night with the antenna sitting on a concrete drive I had a SWR of 1:2.1 on 26.695, 1:2.1 on 27.185, and 1:3.1 on 27.405.
I spoke with local drivers last night on it and I also spoke with Ontario, Canada via skip on 27.385lsb.
The two lapping pieces of fencing that comprise the counterpoise are each 8' x 2' long and wide, and the vertical ended up at 7' long to achieve this SWR. I believe it is possible to flatten the SWR to 1:0.1 by trimming the length of the vertical a little more.
As can be seen I've incorporated a coax choke to remove the coax from acting as the antenna. Coax isolation was important to me in order to show the antenna is the poultry wire only. Note the stand is plywood and a floor flange. Cost of materials - $21.00
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WR954
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Post subject:
Posted: Jun 19, 2010 - 06:40 AM
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Vice-President
Joined: Jul 28, 2008
Posts: 535
Location: Grass Valley, California
Status: Offline
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| Nice, that is the great thing about antennas, if it can conduct, you can probably turn it into an antenna!!!! |
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HomerBB
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Post subject:
Posted: Jun 19, 2010 - 03:24 PM
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DX Alpha
Joined: Mar 18, 2010
Posts: 687
Location: NW Arkansas USA
Status: Offline
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| Yep, |
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2WR1326
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Post subject:
Posted: Jun 19, 2010 - 07:07 PM
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President
Joined: Aug 17, 2007
Posts: 865
Location: Milwaukee, WI
Status: Offline
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HomerBB wrote:
213 wrote:
keep us updated... i like to see stuff like this have you ever played with j-poles? i hear they are fun to mess with
No j-poles, yet. I've looked at them, but on 27Mhz they are pretty big. I'd need a lot of pipe and support for one.
My J is 17 feet long. Not very long for a groundplane... |
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~ Spitfire / 2WR1326 aka Gary. Professional Radio Operator. KD5XRW
Mobile: President Lincoln / Astatic Red Devil / Texas Star DX500v / Wilson 5000 Magnet Mount.
Base: Kenwood TS-430S, PS-430, SP-430, AT-250 / MC-60a / J-Pole.
Spare: President Lincoln #2/ Astatic D104 TUP9 10DA / Kenwood MC-47.
EN53WB :: 27.385 LSB :: Email: 1326 @ DXRW dot ORG :: RoF BBS: telnet://bbs.dxrw.org
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HomerBB
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Post subject:
Posted: Jun 19, 2010 - 11:40 PM
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DX Alpha
Joined: Mar 18, 2010
Posts: 687
Location: NW Arkansas USA
Status: Offline
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| ok. You got me. got specs? |
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HomerBB
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Post subject:
Posted: Aug 27, 2010 - 04:25 PM
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DX Alpha
Joined: Mar 18, 2010
Posts: 687
Location: NW Arkansas USA
Status: Offline
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Latest: Bottom Fed Closed-Sleeve 1/2 wave Monopole Works excellently.
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HomerBB
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Post subject:
Posted: Sep 06, 2010 - 10:27 AM
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DX Alpha
Joined: Mar 18, 2010
Posts: 687
Location: NW Arkansas USA
Status: Offline
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I call this the Qv4k (Quasi vector 4000), a homebrew modeled after the Vector 4000. Seems to work!
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