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2 Meter Slot-Cube Antenna (QST Jan 2019)

Dec 9th 2018, 13:19

K1AWC

Joined: Nov 7th 2014, 13:42
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I would like to know/hear, if anyone has read/built the Antenna in the January QST (Pages 35-36). Please tell me if the dimensions for the antenna are correct. I can't get it to "Fit".
Dec 11th 2018, 17:46

K1AWC

Joined: Nov 7th 2014, 13:42
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I was contacted by John, that the short horizontal is 6"(2) Each..
Dec 14th 2018, 10:21

aa4pf

Joined: Jan 4th 2012, 01:26
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I'm working on building the antenna. I sent John an email suggesting some more details. So far the measurements are OK except that I've had to make the top short horizontal that comes off the top tee about 5 3/8" and the bottom one about 6" to fit better. I've also made up 1" stubbs to connect the tees to the elbows on the 7" vertical. I'm concerned about overheating the CPVC coupling when I solder the last fittings for that mesh. I intend to solder up that section of the antenna first. I'm enjoying the project and look forward to replacing my J-pole.
Dec 22nd 2018, 15:02

KD0MQO

Joined: Sep 7th 2010, 14:01
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Thanks guys. I had the same questions.
Dec 22nd 2018, 16:45

n6lgb

Joined: Apr 1st 2016, 01:16
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Quote by aa4pf
I'm concerned about overheating the CPVC coupling when I solder the last fittings for that mesh.


Wrap a wet rag around the CPVC coupler to sink the heat while soldering.

Dec 24th 2018, 08:33

K2HYD

Joined: Apr 4th 1998, 00:00
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I've built one. Only problem I had is that I should have made the 1" pieces that connect the L's to the T's a bit shorter, or maybe I could have jammed the L's and T's closer together. I had about a 3/16in gap between L's and T's, and this pushed the vertical sections up against each other. I held them apart temporarily with a piece of scrap metal when mounting them to the PVC pipe (there was enough "give" in the whole assembly to allow this). Once mounted and held in place with screws and nuts I could remove the scrap metal piece and everything looks good.
Dec 25th 2018, 15:00

K1AWC

Joined: Nov 7th 2014, 13:42
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4 Each 8.5"
2 Each 8"
2 Each 7"
2 Each 6"
2 Each 3.5"
2 Each 1"
Gap in CPVC connector is 1/8"
10 Each 90* Elbow
2 Each "T" Fittings
Dec 27th 2018, 11:23

KI5BWV

Joined: Oct 18th 2018, 10:44
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Interesting looking project as I live in a restrictive HOA. Has anyone completed the project and measured the gain and SWR? The SWR appears to be low (Figure 2 in the article) but I was unable to determine the projected gain.
Dec 27th 2018, 11:57

SuperdutyCowboy

Joined: Apr 5th 2018, 08:41
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Total Posts: 0
And so we add 2 more pieces of 6 inch pipe. Where do they go? Wow. This isn't going to be anything to teach in the antenna class I see.
Dec 27th 2018, 12:53

K1AWC

Joined: Nov 7th 2014, 13:42
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Looking DOWN at the antenna, North has 1 Each 8.5"
West has 1 Each 8.5"
East has 1 Each 8"
South has 1 Each 6",a "T" fitting, and 1 Each 1".
(2 Sets/N,E,W,S) Stack them Vertical with the 2 Each 7".
Dec 27th 2018, 19:09

KC6ZBE

Joined: Jul 16th 2010, 02:31
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Started to build this yesterday and noticed it didn't "come together" as specified in the article.
Glad I found I wasn't the only one!

Finished the antenna today with the updated dimensions and I am resonant at 152.4 mhz. Checking the 2 meter portion gives me a SWR of 4.2

It was a fun build, but just curious how your guys' cube came out.

Dave
Dec 28th 2018, 19:56

AD6ZH

Joined: Jul 16th 2001, 00:00
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I built as in the article. I bored the T connector on a lathe so it could be adjusted. Best swr was with the T touching the elbow. It resonated at about 150mhz. I reheated joints a pair at a time, bumping with a hammer to extend about 1/4 inch in 3 places. This added about 3/4 to 1 inch to the length of a loop. That brouht resonance to 146, and gave a little more separation to the ends.

Took a while to get there, but passed all the on the air tests sitting on a wooden table. I don't have an antenna range, so can't say what the gain is. Feels like 5-6 db. A bit lower than a 5/8 jpole, but much better than a rubber duck.

Next step is to try it on the car roof to see what a metal plane does to it..
Dec 31st 2018, 13:51

K1AWC

Joined: Nov 7th 2014, 13:42
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I can't give a full report...yet, But this antenna is turning into "FRANKNTENNA". I've made some mods (I will tell more when finished), But I'm still liking this as a portable trip/field antenna. I can hit Repeaters 37 Miles away (MFJ-1918ex 10' stand, Cheap RG58 coax, and a 4 Watt Baofeng UV5-R). Not bad for a start....more to come
Jan 1st, 14:32

K1AWC

Joined: Nov 7th 2014, 13:42
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I spent the day trying different things, and found using 75 Ohm Video Coax dropped the SWR's from 2.4+ (RG-58) to 1.2 !! Runs good SWR's thru the whole Band. I might just be done testing things, this is all I need for my uses. THANKS JOHN, for another GREAT Antenna!
Jan 16th, 15:02

N7LT

Joined: Apr 4th 1998, 00:00
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Total Posts: 0
I started to build this antenna from the article and upon dry fitting the copper fittings, found nothing was coming together properly, Started searching the net and found this form but still have questions...

K1AWC, what mods did you make? You never elaborated on them other than changing the coax to 75 ohm. Did anybody find out why the dimensions are so different than the article? 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? AD6ZH, you said you increased the loop by 1 inch. What were your final dimensions for the loops? Any change to the vertical copper?

Thanks for your help guys! de N7LT

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