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2 Meter Slot-Cube Antenna (QST Jan 2019)

Feb 13th, 09:28

jimvw57

Joined: Dec 16th 2017, 15:23
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I believe different brands of the copper connectors are not all the same length.

kmikemoo did that change the gap between the vertical tubes?
Feb 16th, 23:06

jimvw57

Joined: Dec 16th 2017, 15:23
Total Topics: 0
Total Posts: 0
did some more playing around today and found that by moving the feed point to 4 inches back from the vertical l, I get resonance at 148 Mhz with SWR at 1.3. I attached wire directly to the horizontal tube without using the short stubs with the tee connectors

UPDATE
I took it outside and stuck it in a tree about 6 1/2 ft off the ground, reports from other stations say it is much better than my od J-Pole and lots less background noise, I noticed it also doesn't feedback into my computer speakers.
Feb 26th, 20:32

kmikemoo

Joined: Jun 15th 2018, 21:54
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jimvw57 I didn't change the vertical spacing (which I assumed was the 7" pieces). I just expanded the two squares. I also tried moving the t stubs away from the verticals with the original lengths and I'm pretty sure that my resonant frequency went up. I have yet to put mine on the air. Snow and cold are winning.

Mar 2nd, 16:31

jimvw57

Joined: Dec 16th 2017, 15:23
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same as what I found.
Mar 11th, 06:04

hartford

Joined: Nov 15th 2013, 19:29
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I built the antenna over the past couple of weekends and found that mine also was resonant at 152 MHz. I lengthened two of the horizontal pipe sections 1 1/4" each and the resonant frequency dropped to 146 MHz. The SWR is below 1.3:1 across the band.
I also abandoned the CPVC coupling for two copper end caps, this gives a little more metal to tap into for the coax connection.

I would also like to try this antenna as a mobile as suggested by AD6ZH, and would like to know if anyone has tried it over a ground plane.
Apr 17th, 00:01

KC6ZBE

Joined: Jul 16th 2010, 02:31
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Total Posts: 0
Quote by N7LT
KC6ZBE, your initial resonance at 152Mhz is a LONG way off from the ham band. Did you readjust the size to reach resonance on 2 meters? if so, what are your final measurements?

Thanks for your help guys! de N7LT


Sorry for the late response, OM.

I see a lot of other people got their cube resonant somewhere in the 150mhz range as well with the original specs.
I tried the heating up/hammering out method but gave up. I decided to try to make a new one using K1TGF's dimensions. I like the idea of how he added some length on some sides.

Got a few more pieces to solder and we will see how it goes.
Apr 17th, 19:56

KC6ZBE

Joined: Jul 16th 2010, 02:31
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SUCCESS!

Using K1TGF's dimensions, the new one I built came out resonant enough in the 2 meter portion with an SWR of 1.4 at 146.500 mhz which is just fine by me.

Also, instead of screwing in the feed line to the stubs, I used 3/4in copper pipe strap and wraped it around the 1/2in stubs and secured it with a bolt (if that makes sense).

73
Dave.
Apr 21st, 18:13

jimvw57

Joined: Dec 16th 2017, 15:23
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I used hose clamps so I could adjust where they are positioned. Easier to tune
Apr 30th, 10:19

KG7QJB

Joined: Feb 7th 2015, 15:55
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My swr came out 1.4 at 146.520 using 50 feet of LMR 400 and 5 wraps of choke using a smaller coax on the plastic gray pipe (electrical pvc) . Very impressed with it , works as it should. My pictures are on QRZ.com not sure how to get a picture on here. KG7QRZ Curtis in Pasco, Washington. P.S. some of the lengths were wrong on the copper pipe, figured it out pretty quick that something was wrong.

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