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2 meter slot-cube antenna

Feb 17th, 15:12

K9RJ

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
Seems like there are several different forums for this antenna. Is this normal?
Feb 26th, 22:28

K1WCC

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
Yes, this was a poorly written article. The BOM is not complete, and there should have been a line drawing included. I'm building it, and hope it comes out ok. Tnx for the "correct" parts list.

Feb 27th, 08:46

W1VT

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
http://www.arrl.org/files/file/QST%20Binaries/Jan2019/Slot20Pipe20in%20Inches.jpg

Picture with dimensions labeled.
Mar 12th, 20:23

ve7dvb

Joined: Jul 10th 2011, 19:05
Total Topics: 0
Total Posts: 0
Got a message from W1VT link: http://www.arrl.org/img/file_types/missing.png. The issue I'm having is that instead one of the 8" on the horizontaI am using the 6" on the horizontal (into the Tee) as the top and bottom cubes each can't be built using 2 (8") and 2(8.5"). There is indeed an 1/8" gap inside of the CPVC coupling so the height of the risers has to be 7 to match the length of the feed point pieces. Fun project though.
Mar 14th, 20:54

KC3LMV

Joined: Sep 9th 2018, 15:46
Total Topics: 0
Total Posts: 0
Can this Slot-Cube antenna for 2M be scaled up to a 6M antenna. Is there a conversion factor to go to 6m?
Mar 16th, 10:00

KD5FX

Joined: May 26th 1998, 00:00
Total Topics: 0
Total Posts: 0
I built it from the article and QST online picture. Checked and triple checked all my dimensions. It was resonant at 154 MHz. I tried what W5NBC said to try and put a tab of 1" wide AL foil that is 4" long (just one) on the corner opposite of the match and it now tunes to 146!!! With a bandwidth (2:1) of 145 to 148. So next I will flatten a piece of 1/2" tubing and replace the AL foil with that.
Mar 23rd, 17:38

KB9VSB

Joined: Feb 9th 2000, 00:00
Total Topics: 0
Total Posts: 0
Quote by K1AWC
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
Thanks for the Update!
Mar 30th, 17:39

AC8QB

Joined: Mar 27th 2014, 10:48
Total Topics: 0
Total Posts: 0
Using AL foil works because it's emicivity is different than copper.
A copper sheet only changes the diameter of the tube.

I am making a new version with 0.050 " added to vertical members of the cube.
I tried to add C to tuning but even with a gymic (twisted pair of insulated wire) was too much C.
3rd thing is to use an open stub and see what the smith chart looks like.
Mar 31st, 15:38

KC3LMV

Joined: Sep 9th 2018, 15:46
Total Topics: 0
Total Posts: 0
I was able to find the information on Scaling antennas from and article by W5ALT " Antenna Notes For A Dummy" From that artical and with some math help from my Niece Amy Sefcheck I came up with the following.

NOTE I have NOT built or tested it yet

6 Meter Slot Cube Calculation
WL = Wave Length, Freq Old = 146.5 MZH Freq New= 52 MHZ
WL old =984/ Freq old = 984/146.5mhz = 6.7167
WL new =984/Freq new = 984/52mhz = 18.9230
SF =WL new/WLold = 18.9230/6.7161 = 2.8173
If we round the SF to 2.75 what is the corresponding Freq New
984 / (WL old * New SF) = New SF freq
984/ ( 6.7167 * 2.75) = 53.2729
2 Meter 6 Meter Amount of ½ “ pipe
8.5 * 2.75 = 23.375 23.375 * 6 = 140.25 L in
8 * 2.75 = 22 22 * 2 = 44 Lin
6 * 2.75 = 16.5 16.5 *2 = 33 Lin
4.25 * 2.75 = 11.6875 11.6875 * 2 = 23.375 Lin
1 * 2.75 = 2.75 2.75 * 2 = 5.5 Lin
Total 246.5 Lin = 20.55 LF = 2 and a fraction of 10’ pipes

Mar 31st, 15:57

KC3LMV

Joined: Sep 9th 2018, 15:46
Total Topics: 0
Total Posts: 0
I have built the 2M Slot Cube with the revised pipe lengths. I made it in 3 assemblies. The top loop, the bottom loop and the feed point loop. I did all my work on a capped block wall as it is relatively flat. Then after the assemblies were relative parallel and square I combined them together. I had to do a bit of fussing and adjusting with the finished assembly to get everything relative parallel. I have only tested the antenna attached to a 1.5 " x 4' piece of PVC on top of a 6' ladder. The antenna was cocked downward about 30 deg. It worked marvelously. I hit a 2 repeaters 18 miles away on 20 watts. As far as I can tell from my MFJ SWR meter the SWR is quite good maybe as high as 1.5 : 1 on 50 watts. Ill be doing more testing with it the end of April when I meet up with a friend with a High end Analyzer
Apr 9th, 09:39

WC0G

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
I built this antenna last week with no problems. One thing I did notice while testing it was how sensitive it is to nearby objects. When mounted in the clear the lowest SWR is 1.2 to 1 at 145.8 MHz. When mounted within a few feet of of my house or a tree the SWR jumps up to over 2.0 to 1. SWR was measured using a Rig Expert AA 230. Total build time was about an hour,

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