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Post by lamplighter on May 13, 2009 16:50:53 GMT -5
I am working on a 2 element quad antenna. I noticed that raising it a mere two feet higher brought the SWR down a little. It is only twelve feet from the ground to the boom while working on it. Can I expect a definite improvement on the SWR when I get it up to operating height, 30 - 35 feet? Current SWR at present height is: ch 40 2:1:1 ch 20 1:6:1 ch 1 1:4:1 See it here: www.cirilo.net/cac/2elq/index.htm |
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Post by zman on May 14, 2009 8:13:52 GMT -5
You might try to tune it a little to get the SWRs down a tad on CH 40 unless you have some sort of antenna matcher you can put inline. I tuned my home brew 4 element "monster quad" when i had it mounted on my roof. When i was done i pushed it back up in the air and i had a 1.2-1 on ch 1 and 40 and a flat match on ch 20. Good luck!
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Post by lamplighter on May 14, 2009 8:20:49 GMT -5
Worked on it some more yesterday afternoon:
SWR
ch 40 --- 1:7:1
ch 1 --- 1:4:1
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Post by lamplighter on May 14, 2009 17:24:36 GMT -5
Raised it to 28' at the boom, and the SWR did not improve.
ch 01 ---- 1:4:1
ch 19 ---- 1:7:1
ch 40 ---- 2:0:1
Now back to the matching at new height.
(new photos at same location)
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Post by Marc on May 14, 2009 17:34:53 GMT -5
What type of matching system are you using?
Looks like a 75 ohm piece of coax correct?
Marc
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Post by lamplighter on May 14, 2009 18:00:59 GMT -5
Yes. 75ohm section. Also tried this:
Ant--->75ohm--->50ohm--->75ohm--->50ohm--->TX/TR
-------(1/4wl)---(1/12 wl)---(1/12 wl)---(feedline)-------
Seemed to help at 12' height, but back to bad at 28'...
back to work on it.
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Post by Marc on May 14, 2009 21:34:17 GMT -5
how long is the boom
and how long is the driven element
what Channel is it cut for
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Post by lamplighter on May 14, 2009 21:53:18 GMT -5
Boom: 63"
Edriv 443"
Should be for 27.195
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Post by Marc on May 14, 2009 21:54:49 GMT -5
The boom is a little short should be about 15" longer
but this type of quad is a direct feed.
you just need a 1 to 1 balun about 6 to 8 turns of your feed line
on a 1 and 1/2 inch out side diameter piece of PVC pipe should
do the trick. mount it to the boom right before the element.your
close with 75 . with more boom it can be fine tuned by sliding the
Reflector element back and forth.
the 75 ohm match would be for a longer boom about 10.5 foot spacing.
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Post by lamplighter on May 15, 2009 0:17:45 GMT -5
Thanks. This is some of the best advice I've heard in a while. I'll get that changed around and hopefully will be right on the money soon.
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Post by Marc on May 15, 2009 0:36:43 GMT -5
Remember to leave enough coax in front of the balun to reach the wire driven element. No 75 ohm coax.
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Post by lamplighter on May 15, 2009 8:06:59 GMT -5
Remember to leave enough coax in front of the balun to reach the wire driven element. No 75 ohm coax. No problem. Got it covered. Thanks again. |
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Post by lamplighter on May 15, 2009 18:40:49 GMT -5
I put in the 1:1 balun as suggested. I've got 1:2:1 on ch 01, 1:4:1 on ch 19, and 1:7:1 on ch 40. I haven't done anything with the spacing yet, so there's more room for improvement. I am happy with the positive change so far. Thanks again.
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Post by Marc on May 15, 2009 23:51:49 GMT -5
Any time that is what we are here for.
FYI The short boom give you a narrower bandwidth on your swrs.
Marc
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Post by lamplighter on May 16, 2009 21:32:07 GMT -5
No time to do any more work on the beam, yet. This evening at 8:00 PM I came in from work and DX was rolling. I was unable to bust up any pile-ups on the Cb 40 so dropped down a band. This is where the SWR is best right now.
Contacts:
Little Granny in Kentucky 26.895
150 Kentucky 26.905
142 W Virginia 26.915
Bloodhound Kentucky 26.815
Took a chance and jumped up to 27.515 lsb
347 Jamaica
I am anxious about getting the antenna properly setup. No telling how much fun I'll have.
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Post by lamplighter on May 19, 2009 21:39:40 GMT -5
Ok. Brought the antenna down and did it over again. Made a few adjustments and it affected my SWR positively: 28.755 --------- 1.7:1 28.305 --------- 1.2:1 27.855 --------- 1.2:1 27.405 --------- 1.2:1 26.965 --------- 1.1:1 26.515 --------- 1.0:1 26.065 --------- 1.5:1 25.615 --------- 4.0:1 25.165 --------- 4.0:1 Also got it up a little higher from 27 feet to 35 feet at the boom. No skip this evening to work it out on, and the locals are all enjoying the great outdoors.   |
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Post by Marc on May 20, 2009 9:43:59 GMT -5
Looks good! how did the rejection turn out?
Marc
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Post by lamplighter on May 20, 2009 9:57:28 GMT -5
Rejection is still not what I had hoped. I'd love to be able to shut out the back door, but it only drops about 2 - 3 S units. Probably would need a more ambitious project to get all I want.
BTW, you can see this suggestion ...you just need a 1 to 1 balun about 6 to 8 turns of your feed line on a 1 and 1/2 inch out side diameter piece of PVC pipe should do the trick... of yours in the photo. I had the length of the 75ohm Q section a little short, too.
In combination with adjustments on wire length, going to bare wire, spacing/length tweaks, and perhaps the height change, I have improvements.
We'll see what kind of talking it does...
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Post by Marc on May 20, 2009 10:08:46 GMT -5
Glade to see it turning out for you hope it talks as good as it looks!!
Marc
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Post by lamplighter on May 23, 2009 10:03:38 GMT -5
DX Contacts:
5/20/09
333 ----------------------------- Bristol, Tenn.
454 ------------------------------ Virginia
Bigman 47 Tango Charlie -----N Carolina
91 Grease Monkey ------------ S Carolina 27.285
47 ------------------------------- Lake Erie, Ontario, Canada 27.385 lsb
83 ------------------------------- Virginia
340 ------------------------------ SW Virginia
5/21/09
183 ----------------------------- S Carolina 26.755
1269 ---------------------------- Kentucky 26.825
009 ----------------------------- Kentucky 26.825
151 ----------------------------- N Carolina 26.825
Carolina Mobile--------------- N Carolina 26.925
5/22/09
ImaHead ---------------------- Florida 27.285
175 ---------------------------- Georgia 27.225
974 ---------------------------- S Carolina 27.405
Bush Hog --------------------- Jackson, TN 26.835
153 ---------------------------- Jackson, TN 26.835
Barefoot Hillbilly ------------ TN? 27.315
Gentleman Jack ------------- Lynchburg, TN 27.105
218 ---------------------------- Oxford, GA 26.915
747 Slick ---------------------- Coopville, TN 27.345
2Pill---------------------------- Alabama 27.225
726 ---------------------------- N Carolina 27.345
143 Wildman ----------------- SE Tennessee 27.325
Dodge Boy ------------------- Columbia, S Carolina
As an aside:
full wave loop skywire in attic:
Hamburger Man (spreading that mayonaise) -----Carolian/Georgia line 27.225
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Post by badnews456 on May 23, 2009 14:13:00 GMT -5
LAMPLIGHTER, GIVE ME CALL 38 LSB NWR 23 GA. BADMEWS.
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Post by lamplighter on May 23, 2009 14:19:13 GMT -5
LAMPLIGHTER, GIVE ME CALL 38 LSB NWR 23 GA. BADMEWS. Next opportunity I'll give it a whirl. Call on LSB is LimaDelta 183 or LD 183 AM it's 183 NW Arkansas Country Preacher Radio Broadcasting |
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Post by lamplighter on Feb 15, 2010 18:31:58 GMT -5
Due to my rotor being on the blink I put my homemade 5/8^ back in the air and immediately made a contact with 0547 Kingston Jamaica mobile on 27.535LSB from 183 NW Arkansas  |
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